[Federal Register Volume 70, Number 193 (Thursday, October 6, 2005)]
[Proposed Rules]
[Pages 58508-58561]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-19419]



[[Page 58507]]

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Part II





Department of Transportation





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Federal Aviation Administration



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14 CFR Parts 1, 25, 91, etc.



Enhanced Airworthiness Program for Airplane Systems/Fuel Tank Safety 
(EAPAS/FTS); Proposed Advisory Circulars; Proposed Rule and Notices

  Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 / 
Proposed Rules  

[[Page 58508]]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Parts 1, 25, 91, 121, 125, 129

[Docket No. FAA-2004-18379; Notice No. 05-08 ]
RIN 2120-AI31


Enhanced Airworthiness Program for Airplane Systems/Fuel Tank 
Safety (EAPAS/FTS)

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The intent of this proposal is to help ensure the continued 
safety of commercial airplanes by improving the design, installation, 
and maintenance of their electrical wiring systems as well as by 
aligning those requirements as closely as possible with the 
requirements for fuel tank system safety. This proposed rulemaking 
consists of regulatory changes affecting wiring systems and fuel tank 
systems in transport category airplanes. First, it proposes to organize 
and clarify design requirements for wire systems by moving existing 
regulatory references to wiring into a single section of the 
regulations specifically for wiring and adding new certification rules. 
It also proposes to require holders of type certificates for certain 
transport category airplanes to conduct analyses of their airplanes and 
make necessary changes to existing Instructions for Continued 
Airworthiness (ICA) to improve maintenance procedures for wire systems. 
It would require operators to incorporate those ICA for wiring into 
their maintenance or inspection programs. And finally, this proposed 
rulemaking would clarify requirements of certain existing rules for 
operators to incorporate ICA for fuel tank systems into their 
maintenance or inspection programs.

DATES: Send your comments on or before February 3, 2006.

ADDRESSES: You may send comments [identified by Docket Number FAA-2004-
18379] using any of the following methods:
     DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
     Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
     Mail: Docket Management Facility; U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, 
Washington, DC 20590-001.
     Fax: 1-202-493-2251.
     Hand Delivery: Room PL-401 on the plaza level of the 
Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    For more information on the rulemaking process, see the 
SUPPLEMENTARY INFORMATION section of this document.
    Privacy: We will post all comments we receive, without change, to 
http://dms.dot.gov, including any personal information you provide. For 
more information, see the Privacy Act discussion in the SUPPLEMENTARY 
INFORMATION section of this document.
    Docket: To read background documents or comments received, go to 
http://dms.dot.gov at any time or to Room PL-401 on the plaza level of 
the Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT: Stephen Slotte, ANM-111, Airplane & 
Flight Crew Interface, Federal Aviation Administration, 1601 Lind 
Avenue SW., Renton, WA 98055-4056; telephone (425) 227-2315; facsimile 
(425) 227-1320, e-mail [email protected] (certification rules) or 
Fred Sobeck, AFS-304, Aircraft Maintenance Division, Federal Aviation 
Administration, 800 Independence Avenue, SW., Washington, DC 20591; 
telephone: (202) 267-7355; facsimile (202) 267-7335, e-mail 
[email protected] (operating rules).

SUPPLEMENTARY INFORMATION:

Comments Invited

    The FAA invites interested persons to participate in this 
rulemaking by submitting written comments, data, or views. We also 
invite comments relating to the economic, environmental, energy, or 
federalism impacts that might result from adopting the proposals in 
this document. The most helpful comments reference a specific portion 
of the proposal, explain the reason for any recommended change, and 
include supporting data. We ask that you send us two copies of written 
comments.
    We will file in the docket all comments we receive, as well as a 
report summarizing each substantive public contact with FAA personnel 
about this proposed rulemaking. The docket is available for public 
inspection before and after the comment closing date. If you wish to 
review the docket in person, go to the address in the ADDRESSES section 
of this preamble between 9 a.m. and 5 p.m., Monday through Friday, 
except Federal holidays. You may also review the docket using the 
Internet at the Web address in the ADDRESSES section.
    Privacy Act: Using the search function of our docket Web site, 
anyone can find and read the comments received into any of our dockets, 
including the name of the individual sending the comment (or signing 
the comment on behalf of an association, business, labor union, etc.). 
You may review DOT's complete Privacy Act Statement in the Federal 
Register published on April 11, 2000 (65 FR 19477-78) or you may visit 
http://dms.dot.gov.
    Before acting on this proposal, we will consider all comments we 
receive on or before the closing date for comments. We will consider 
comments filed late if it is possible to do so without incurring 
expense or delay. We may change this proposal in light of the comments 
we receive.
    If you want the FAA to acknowledge receipt of your comments on this 
proposal, include with your comments a pre-addressed, stamped postcard 
on which the docket number appears. We will stamp the date on the 
postcard and mail it to you.

Availability of Rulemaking Documents

    You can get an electronic copy using the Internet by:
    (1) Searching the Department of Transportation's electronic Docket 
Management System (DMS) Web page (http://dms.dot.gov/search);
    (2) Visiting the FAA's Regulations and Policies Web page at http://www.faa.gov/regulations_policies/; or
    (3) Accessing the Government Printing Office's Web page at http://www.gpoaccess.gov/fr/index.html.
    You can also get a copy by submitting a request to the Federal 
Aviation Administration, Office of Rulemaking, ARM-1, 800 Independence 
Avenue SW., Washington, DC 20591, or by calling (202) 267-9680. Make 
sure to identify the docket number, notice number, or amendment number 
of this rulemaking.

Organization of This NPRM

    Discussion of the proposal in this NPRM is organized under the 
following headings. Material supplementary to this discussion, but not 
included in it, appears in appendices at the end of the discussion, 
before ``List of Subjects.'' Whenever there is a reference to a 
document being included in the docket

[[Page 58509]]

for this NPRM, the docket referred to is Docket Number FAA-2004-18379. 
A list of acronyms used is included as Appendix A. Unless stated 
otherwise, rule sections referenced in this NPRM are part of Title 14 
of the Code of Federal Regulations.

Table of Contents

I. Executive Summary
II. Background
    A. Flight 800 Accident
    B. Flight 111 Accident
    C. FAA Aging Transport Nonstructural Systems Plan
    D. Fuel Tank Safety Rule
    E. Existing Wiring Certification Regulations
III. General Discussion of the Proposal
    A. Nature of the Problem
    B. Relationship of this Proposal to Other Aging Aircraft 
Initiatives
    C. Alternatives to Rulemaking
IV. Overview of Proposal
V. Section-by-Section Discussion of Proposed Rules
    A. Part 25 Subpart H-Electrical Wiring Interconnection Systems 
(EWIS)
    B. Part 25 Subpart I--Continued Airworthiness and Related Part 
25 Changes
    C. Other Proposed Changes to Part 25
    D. Part 25 Electrical System Harmonization Rules
    E. Proposed Changes to Part 91, 121, 125, and 129 Operating 
Rules for Fuel Tank Systems and EWIS and Other Existing Continued-
Airworthiness-Related Rules
    F. Proposed Changes to Parts 121 (Subpart Y) and 129 (Subpart 
B)-EWIS Maintenance Programs
    G. Proposed Changes to Parts 91 (Subpart L), 121 (Subpart Y), 
125 (Subpart M), and 129 (Subpart B) ( Fuel Tank Maintenance 
Programs
    H. Advisory Circulars
VI. Regulatory Analyses and Notices
Appendices
    Appendix A--List of Acronyms
    Appendix B--Correlation Between Proposed New Part 25 Regulations 
and Existing Regulations
    Appendix C--Correlation Between Existing Part 25 Regulations and 
Proposed New Regulations
    Appendix D--Existing Part 25 Requirements Requiring Revision to 
Support the New Proposed Regulations
    Appendix E--Flowchart 1: Pre- and Post-Type Certification Safety 
Analysis Concept--Flowchart 2: Post-TC Safety Analysis Concept

I. Executive Summary

    Safety concerns about wiring systems in airplanes were brought to 
the forefront of public and governmental attention by a mid-air 
explosion in 1996 involving a 747 airplane. Ignition of flammable 
vapors in the fuel tank was the probable cause of that fatal accident 
and the most likely source was determined to be a wiring failure 
causing a spark to enter the fuel tank. All 230 people aboard were 
killed. Two years later, an MD-11 airplane crashed into the Atlantic 
Ocean, killing all 229 people aboard. Although an exact cause could not 
be determined, a region of resolidified copper on a wire of the in-
flight-entertainment system cable indicated that wire arcing had 
occurred in the area where the fire most likely originated.
    Investigations of those accidents and subsequent examinations of 
other airplanes showed that deteriorated wiring, corrosion, improper 
wire installation and repairs, and contamination of wire bundles with 
metal shavings, dust, and fluids, which would provide fuel for fire, 
were common conditions in representative examples of the ``aging fleet 
of transport airplanes.'' The FAA concluded that current maintenance 
practices do not adequately address wiring components, wiring 
inspection criteria are too general, and unacceptable conditions, such 
as improper repairs and installations, are not described in enough 
detail in maintenance instructions. Wiring failures result in airplane 
delays, unscheduled landings, in-flight entertainment system problems, 
nonfatal accidents, and fatal accidents.
    Up until this time, airplane wiring has never been singled out for 
special attention during maintenance inspections. Although close 
attention is paid to safe design within systems, we had assumed that 
for the wiring providing power to those systems, standard industry 
practice was appropriate, and modifications have often been performed 
without scrutiny for the effect their wiring additions may have on 
other systems in the airplane. Damaged wire and insulation can cause 
electrical arcing, providing the spark that can cause fire. Dust, dirt, 
lint, contamination, and vapors provide fuel for fire. Recent rules 
have established requirements for wiring connected to fuel tank 
systems. This proposal goes further, to address all the wiring 
contained in an airplane as systems on their own and provide scrutiny 
to the conditions that affect their safe functioning. It aligns with 
the requirements for fuel tank wiring.
    We are proposing new maintenance, inspection, and design criteria 
for airplane wiring to address conditions that put transport airplanes 
at risk of wire failures, smoke, and fire. We are proposing 
requirements for type certificate holders and applicants for type 
certificates and supplemental type certificates to analyze all the 
zones of their airplanes for the presence of wire and for the 
likelihood of contaminant materials. The proposal would also require 
them to develop maintenance and inspection tasks to identify, correct, 
and prevent wiring conditions that cause risk to continued safe flight. 
We are proposing that these tasks be included in new instructions for 
continued airworthiness for wiring and that they be compatible with 
instructions for continued airworthiness for fuel tank systems. We are 
further proposing to amend Title 14 Code of Federal Regulations (CFR) 
parts 91, 121, 125 and 129 operating rules to require operators of 
transport airplanes to incorporate those tasks for wiring and fuel 
tanks into their regular maintenance programs. Finally, we are creating 
a new subpart of part 25 to contain all applicable certification 
requirements for airplane wiring, including new rules to improve safety 
in manufacture and modification.
    The total estimated benefits of the proposal are comprised of 
efficiency benefits and safety benefits. The efficiency benefits are 
$192.3 million ($78.3 million present value). The safety benefits are 
$563 million ($262.4 million present value). From 1995-2002, 397 wiring 
failures were reported. We used industry estimates to determine that 
68% of those failures would be detectable. The 7 most common--burned, 
loose, damaged, shorted, failed, chafed, and broken wires--account for 
84% of all wiring failures. Wiring failures cause 22.1 flight delays 
per year, with an average time of 3.5 hours and an estimated cost of 
approximately $35,639 each, and without this proposal, we believe that 
wiring delays will increase proportionately with the growth of the 
fleet. Wiring failures cause 27.5 unscheduled landings per year at an 
average cost of approximately $200,461 per unscheduled landing. We 
estimate that, based on expected fleet growth of 3.82% per year, there 
will be 1,118 unscheduled landings caused by wiring failures over a 25-
year period, of which approximately 760 would be prevented by this 
proposal, resulting in a total benefit of averting unscheduled landings 
of $152.4 million. Delays and unscheduled landings contain safety risks 
for passengers and crew and increase the likelihood of a more serious 
event. We estimate 32.8 wiring-related incidents or accidents could be 
prevented by this proposal in the next 25 years, for a total safety 
benefit of $563 million ($262.4 million present value). This includes 
1.2 fatal accidents that can be prevented.
    The estimated total cost of this NPRM is $474.4 million ($209.2 
million present value) over 25 years. The total estimated benefits are 
$755.3 million

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($340.7 million present value) over the same period. This proposal is 
meant to proactively address wiring conditions existing in the 
transport airplane fleet that we now know affect safe flight and can be 
detected, corrected, or prevented.

II. Background

A. Flight 800 Accident

    Safety concerns about wiring systems in airplanes were brought to 
the forefront of public and governmental attention by a 1996 accident 
over the Atlantic Ocean near East Moriches, New York, involving a 747-
131 airplane, operated as TWA Flight 800. That accident was 
investigated extensively by the National Transportation Safety Board 
(NTSB). It also prompted the FAA to investigate fuel tank wiring, and 
to focus on aging wiring in general. On May 7, 2001, the FAA published 
a final rule titled ``Transport Airplane Fuel Tank System Design 
Review, Flammability Reduction, and Maintenance and Inspection 
Requirements'' (66 FR 23086) to specifically address safety of the fuel 
tank, including wiring, which was determined to be the probable cause 
of the TWA Flight 800 accident. This NPRM addresses safety concerns 
related to aging wiring in general, and incorporates maintenance 
requirements specific to fuel tanks.
    The NTSB determined the probable cause of the TWA Flight 800 
accident, in which the airplane broke up in flight, was an explosion of 
the center wing fuel tank (CWT) resulting from ignition of the 
flammable fuel and air mixture in the tank. The source of ignition 
energy for the explosion could not be determined with certainty. 
However, of all the sources evaluated, the most likely was a wiring 
failure outside the CWT. This failure allowed excessive electrical 
energy to enter the CWT through electrical wiring associated with the 
fuel quantity indication system (FQIS).
    During its investigation, the NTSB found several potentially unsafe 
conditions in and near the electrical wiring of the accident airplane. 
The findings included cracked wire insulation, metal shavings adhered 
to a floor beam where FQIS wires would have been routed (consistent 
with maintenance records describing compressed air being used to blow 
metal shavings off avionics units), other debris, and sulfide deposits. 
In addition, it found evidence of several repairs that did not comply 
with the guidelines in Boeing's ``Standard Wiring Practices Manual'' 
(SWPM). Noncompliant repairs included:
     Use of an oversized strain relief clamp on the terminal 
block of the number 1 fuel tank compensator. The clamp did not 
adequately secure the wires.
     Many open-ended (rather than sealed) wire splices, which 
exposed conductors to possible water contamination.
     Several wire bundles containing many wire splices on 
adjacent wires at the same location.
     Excessive solder on the connector pins inside the fuel 
totalizer gauge. The solder had apparently caused inadvertent joining 
of connecting pins/wires from the right main fuel tank and CWT FQIS.
    Some of these conditions may suggest the need for improved 
maintenance. However, the NTSB found that deterioration, damage, and 
contamination of aircraft wiring and related components, such as those 
found on the accident airplane, were common in other transport category 
airplanes inspected as part of the accident investigation. This was 
especially true in older airplanes. The NTSB concluded that ``the 
condition of the wiring system in the accident airplane was not 
atypical for an airplane of its age and one that had been maintained in 
accordance with prevailing industry practices.''
    The NTSB expressed concern about the damage and contamination found 
on electrical wiring and components during their examinations of 
numerous transport category airplanes, including the accident airplane. 
The conditions found were especially disturbing because it was clear 
from those examinations that much aircraft wiring is difficult, if not 
impossible, to inspect and test because of its inaccessibility.
    The NTSB concluded that inadequate attention to the condition of 
aircraft electrical wiring had resulted in potential safety hazards. 
The conclusions from the accident investigation brought a heightened 
awareness to the FAA, other government agencies, and the general public 
of the importance of maintaining the integrity of aircraft wiring. A 
copy of the NTSB findings (NTSB Aircraft Accident Report Number AAR-00/
03) can be found on the NTSB Web site http://www.NTSB.gov, and is 
contained in the docket.

B. Flight 111 Accident

    Two years after the Flight 800 accident, in September 1998, an MD-
11 airplane, operated as Swissair Flight 111, crashed into the Atlantic 
Ocean off the coast of Nova Scotia, Canada. There were no survivors. 
Within approximately 53 minutes of the airplane's departure from New 
York to Geneva, Switzerland, the flightcrew smelled an abnormal odor in 
the cockpit. The cockpit voice recorder indicates that they thought the 
smell was coming from the air-conditioning system. A short time after 
the flightcrew noticed the smell, there was smoke in the cockpit, and 
they diverted the airplane to the Halifax airport.
    While preparing for landing, the flightcrew were unaware that fire 
was spreading above the ceiling in the front of the aircraft. They 
declared an emergency and signaled a need to land immediately. About 
one minute later, radio communications and secondary radar contact with 
the aircraft were lost, and the flight recorders stopped functioning. 
About five and one-half minutes later, the aircraft crashed into the 
ocean.
    In its final report, ``Aviation Investigation Report, In-Flight 
Fire Leading to Collision with Water,'' Report Number A98H0003, the 
Transportation Safety Board of Canada (TSB) (the Canadian governmental 
body charged with aircraft accident investigation) could not identify 
the exact cause of the fire. As part of its 11 findings of causes and 
contributing factors, however, the TSB stated that: ``A segment of in-
flight entertainment network power supply unit cable exhibited a region 
of resolidified copper on one wire that was caused by an arcing event. 
This resolidified copper was determined to be located in the area where 
the fire most likely originated. This arc was likely associated with 
fire initiation event; however, it could not be determined whether this 
arced wire was the lead event.'' That report can be found in the 
docket.
    In the section of the report entitled ``Findings as to Risk,'' the 
TSB cited 24 separate risks that had the potential to degrade aviation 
safety but could not be shown to have played a direct role in the 
event, or are unrelated to this event but were found during the 
investigation. Among those findings of risks are the following 
statements. (The numbers under which each finding appears in the TSB 
report are indicated.)
     ``Regulations do not require that aircraft be designed to 
allow for the immediate de-powering of all but the minimum essential 
electrical systems as part of an isolation process for the purpose of 
eliminating potential ignition sources.'' (3.2.3)
     ``Examination of several MD-11 aircraft revealed various 
wiring discrepancies that had the potential to result in wire arcing. 
Other agencies have found similar discrepancies in

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other aircraft types. Such discrepancies reflect a shortfall within the 
aviation industry in wire installation, maintenance, and inspection 
procedures.'' (3.2.7)
     ``The consequence of contamination of an aircraft on its 
continuing airworthiness is not fully understood by the aviation 
industry. Various types of contamination may damage wire insulation, 
alter the flammability properties of materials, or provide fuel to 
spread a fire. The aviation industry has yet to quantify the impact of 
contamination on the continuing airworthiness and safe operation of an 
aircraft.'' (3.2.8)
     ``There is no guidance material to identify how to comply 
with the requirements of Federal Aviation Regulation (FAR) 25.1353(b) 
[relating to cable routing] in situations where physical/spatial wire 
separation is not practicable or workable, such as in confined areas.'' 
(3.2.10)
     ``Inconsistencies with respect to CB (circuit breaker) 
reset practices have been recognized and addressed by major aircraft 
manufacturers and others in the aviation industry. Despite these 
initiatives, the regulatory environment, including regulations and 
advisory material, remains unchanged, creating the possibility that 
such ``best practices'' will erode or not be universally applied across 
the aviation industry.'' (3.2.12)
     ``FAR 25.1309 requires that a system safety analysis be 
accomplished on every system installed in an aircraft; however, the 
requirements of FAR 25.1309 are not sufficiently stringent to ensure 
that all systems, regardless of their intended use, are integrated into 
the aircraft in a manner compliant with the aircraft's type 
certificate.'' (3.2.21)
    In addition to the two accidents discussed above, multiple 
incidents and accidents that have occurred over the years illustrate 
the types of wire malfunctions that can affect flight safety. A 
discussion of some of those, titled ``EAPAS NPRM Supplemental Material, 
Other Incidents and Accidents Involving Electrical Wiring,'' is 
included in the docket for this NPRM.

C. FAA Aging Transport Nonstructural Systems Plan

    After the Flight 800 accident, at the recommendation of the White 
House Commission on Aviation Safety and Security (WHCSS), the FAA 
expanded its Aging Aircraft Program, which in the past had focused on 
structures, to cover nonstructural systems. We formed a team to study 
aging nonstructural systems and conduct detailed physical evaluations 
of aging airplanes. We reviewed the report from that study team, along 
with information from meetings with FAA principal inspectors and 
representatives of major airplane manufacturers, as well as an analysis 
of airplane service histories. From this combined information, we 
developed the Aging Transport Nonstructural Systems Plan (included in 
the docket for this NPRM). The plan's primary focus is on electrical 
wiring systems. There are other on-going research and development 
activities that address mechanical and avionics systems.
    The July 1998 Aging Transport Nonstructural Systems Plan includes 
results of the evaluation of five transport category airplanes 
considered representative of the ``aging fleet of transport 
airplanes.'' The FAA found conditions similar to those the NTSB found 
during its investigation of the TWA Flight 800 accident. Those 
conditions included:
     Deterioration of wiring and related components.
     Stiff and cracked wire.
     Contamination of wire bundles with metal shavings, dust, 
and fluids.
     Corrosion on connector pins.
     Improper wire installation and repairs.
    The FAA also found, as had NTSB investigators, that wires contained 
in wire bundles are difficult to inspect.
    The conclusions reached from this evaluation were that:
     Current maintenance practices do not adequately address 
wiring components.
     Wire inspection criteria are too general.
     Unacceptable conditions, such as improper repairs and 
installations, are not described in enough detail in maintenance 
instructions.
     Repair instructions and data are difficult to extract from 
SWPMs.
     The information that maintenance personnel are given for 
wire replacement may not be adequate.
     Current incident/maintenance reporting procedures do not 
allow for easy identification of failures.
    The NTSB agreed with these conclusions.
    The Aging Transport Nonstructural Systems Plan detailed several 
tasks and associated subtasks aimed at correcting these problems, 
including:
     Improving wiring inspection criteria and providing more 
detailed descriptions of undesirable conditions.
     Improving inspector training to ensure that it adequately 
addresses the recognition and repair of aging wiring components.
     Developing new methods for nondestructive testing of 
wiring.
    The NTSB responded to the issues defined in the Aging Transport 
Nonstructural Systems Plan. They concluded that they are important 
safety issues and must be fully addressed through rulemaking or other 
means. Specifically addressed by the NTSB (NTSB Recommendation No. A-
00-108, included in the docket) were the need for:
     Improved training of maintenance personnel to ensure 
adequate recognition and repair of potentially unsafe wiring 
conditions;
     Improved documentation and reporting of potentially unsafe 
electrical wiring conditions; \1\ and
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    \1\ Recommendations for improved documentation and reporting and 
for incorporation of new technology are not addressed by this 
proposed rule. They are, however, part of the FAA's Enhanced 
Airworthiness Program for Airplane Systems (EAPAS). The EAPAS 
report, dated October 15, 2002, can be found in the docket for this 
NPRM. For a discussion of training, see ``ATSRAC Recommendations for 
Rulemaking'' in the same docket.
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     Incorporation of the use of new technology, such as arc-
fault circuit breakers and automated wire test equipment.
    The NTSB also recommended (NTSB Recommendation A-00-106, included 
in the docket) that the FAA review the design specifications for 
aircraft wiring systems of all U.S.-certified aircraft and then:
     Identify which systems are critical to safety; and
     Require revisions, as necessary, to ensure that adequate 
separation is provided for the wiring related to those critical 
systems.
    Finally, the NTSB recommended that the FAA ensure that all part 25 
transport category airplanes, regardless of whether they are operated 
under parts 91, 121, 125, or 135, be included in the review of aging 
transport airplane systems and structures (NTSB Recommendation A-00-
119, contained in the docket).
    The FAA Administrator established a formal advisory committee (the 
Aging Transport Systems Rulemaking Advisory Committee, or ATSRAC) in 
1998. Its purpose was to facilitate actions recommended by the Aging 
Transport Nonstructural Systems Plan (FAA Order 11110.127, Aging 
Transport Systems Rulemaking Advisory Committee, dated Jan. 19, 1999, 
included in the docket). This committee is made up of representatives 
of aircraft manufacturers, transport airplane operators, aerospace and 
industry associations, and governmental agencies.
    In January 1998, the FAA assigned five tasks to ATSRAC. These 
included collecting data on aging wiring systems through airplane 
inspections, reviewing

[[Page 58512]]

airplane manufacturers' service information, reviewing operators' 
maintenance programs, and providing the FAA with recommendations to 
improve the safety of those systems. ATSRAC's work on those tasks 
focused on transport category airplanes.
    The ATSRAC review of data (The ``Aging Systems Task Force Aging 
Transport Systems Task 1 and Task 2 Final Report,'' included in the 
docket) yielded the following wiring-related findings:
     Nine B-727 airplanes inspected; 276 discrepancies found.
     Nine B-737 airplanes inspected; 399 discrepancies found.
     Seven B-747 airplanes inspected; 238 discrepancies found.
     Fourteen DC-8 airplanes inspected; 974 discrepancies 
found.
     Fifteen DC-9 airplanes inspected; 116 discrepancies found.
     Fourteen DC-10 airplanes inspected; 714 discrepancies 
found.
     Three L-1011 airplanes inspected; 247 discrepancies found.
     Ten A-300 airplanes inspected; 408 discrepancies found.
    The results from those five initial tasks showed that problems 
related to wiring systems on aging airplanes were not entirely related 
to degradation over time. Inadequate installation and maintenance 
practices were identified as factors that can lead to what is commonly 
referred to as an ``aging system'' problem. As a result, the scope of 
ATSRAC's work was expanded to include improving the continued 
airworthiness of airplane systems, particularly wiring systems.
    In May 2001, the FAA assigned four new tasks to the committee to 
carry out the ATSRAC recommendations on the first five tasks (66 FR 
29203). These next tasks were to accomplish the following:
     Address the need for new wire system certification 
requirements.
     Propose changes to the standard wiring practices manual.
     Develop a training program for wire systems.
     Develop maintenance criteria for wire systems.
    The results discussed earlier from ATSRAC's review of the eight 
models of large transport category airplanes had heightened concern 
about whether similar conditions existed in small transport category 
airplanes (airplanes with a 6- to 30-passenger seating capacity). As a 
result, in March 2002 (67 FR 9799), the FAA assigned another task to 
ATSRAC--to investigate and develop recommendations to improve the 
safety of electrical wiring systems in transport category airplanes 
certificated for fewer than 30 passengers. In response to this task, 
ATSRAC examined the applicability of their previous recommendations to 
this group of airplanes and identified issues unique to electrical 
wiring systems on small transport category airplanes. ATSRAC's work in 
this area is continuing.
    Another investigative group functioning within ATSRAC, whose wiring 
inspections extended to the laboratory, was the Intrusive Inspection 
Working Group (IIWG).\2\ The IIWG subjected selected wire installations 
on six decommissioned airplanes to an intensive, detailed visual 
inspection, followed by destructive testing and laboratory analysis (an 
intrusive inspection). They studied the results to assess the state of 
wire on aged airplanes as a function of wire type and service history. 
In addition, the results from the visual inspections were compared with 
the nondestructive testing and laboratory analysis to determine the 
efficacy of visual inspections for the detection of age-related 
deterioration.
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    \2\ The IIWG was a separate but parallel group within the Aging 
Systems Task Force (ASTF). The Air Transport Association (ATA) 
formed the ASTF in June 1998 to review the effectiveness of 
maintenance on electrical wiring systems and assess the condition of 
those systems on aircraft with type certificates (TC) older than 20 
years. When ATSRAC was formed in 1998, it continued the work started 
under the ASTF.
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    The findings from the IIWG were documented in the ``Transport 
Aircraft Intrusive Inspection Project (An Analysis of the Wire 
Installations of Six Decommissioned Aircraft) Final Report,'' issued on 
December 29, 2000 (from now on referred to as ``Intrusive Inspection 
Report''). A copy is included in the docket. The findings showed that 
wire-related failures have multiple causes. These include:
     Localized heat damage.
     Breaches in wire insulation.
     Wire embrittlement.
     Charred wire insulation.
     Missing insulation.
     Chafing.
     Arcing.
     Arc tracking.
     Reduced insulation resistance in certain wires.
     Defective and broken connectors.
     Damage to connector backshells.
    Both the nonintrusive, visual inspections on the airplane and the 
intrusive inspections found most wiring discrepancies were in areas of 
frequent maintenance activity. In addition, fluid contamination and 
dust and dirt accumulations were common in those areas.
    The Intrusive Inspection Report identified several areas that 
required special emphasis. Three areas--the cockpit, electrical power 
centers, and power feeder cables--were considered critical. This is 
because chafing on wiring in these areas, combined with flammable 
materials close by, can result in severe outcomes, such as wire-to-
structure or wire-to-wire shorting and arcing. Since a fire in these 
areas could present a high risk to continued safe flight and landing, 
the IIWG recommended more detailed inspections for those three areas. 
The intent was to ensure potential problems are identified and 
corrected. This effort led to the development of an enhanced zonal 
analysis procedure (EZAP) to assess risk for fire so that maintenance 
programs developed for wire systems in such critical areas would 
require more detailed inspections. An EZAP is a specific wire-focused 
version of the zonal analysis procedure widely used to analyze an 
airplane's physical areas or zones. It's used for developing 
maintenance tasks. One version of an EZAP is described in proposed AC 
120-XX, ``Program to Enhance Transport Category Airplane Electrical 
Wiring Interconnection System Maintenance.''
    ATSRAC made a number of recommendations to the FAA. Those 
recommendations and the FAA's responses to them are included in the 
docket in the document titled ``ATSRAC Recommendations for 
Rulemaking.'' ATSRAC working groups also produced four proposed 
advisory circulars (AC) as guidance for their recommended rulemaking. 
These proposed ACs are on the topics of wiring system maintenance, 
training, standard wiring practices manuals, and the proposed subpart 
H, and will be briefly discussed at the end of this preamble under the 
heading ``Advisory Circulars.''

D. Fuel Tank Safety Rule

    In addition to the activities described earlier, in response to the 
TWA 800 accident, the FAA has developed an extensive program to address 
safety problems associated specifically with fuel tanks. As mentioned 
previously, on May 7, 2001, the FAA issued a final rule entitled, 
``Transport Airplane Fuel Tank System Design Review, Flammability 
Reduction, and Maintenance and Inspection Requirements.'' This 
discussion refers to that final rule as the ``Fuel Tank Safety Rule.'' 
The Fuel Tank Safety Rule was issued to address unforeseen failure 
modes and the lack of specific maintenance procedures that could result 
in degrading the design safety features intended to preclude ignition 
of fuel tank vapors.
    One part of the Fuel Tank Safety Rule, Special Federal Aviation 
Regulation 88,

[[Page 58513]]

(SFAR 88) applies to design approval holders of certain turbine-powered 
transport category airplanes, and any person who modifies those 
airplanes later. SFAR 88 requires these regulated parties to perform 
safety assessments to confirm if the design of the fuel tank system 
precludes the existence of ignition sources in the fuel tank system. 
SFAR 88 also requires development of design changes and maintenance and 
inspection instructions to assure the safety of the fuel tank system.
    Other sections of the Fuel Tank Safety Rule (referred to as the 
``operational rules'') require that operators of those airplanes 
include fuel tank safety maintenance and inspection instructions in 
their existing maintenance or inspection programs. The requirements of 
those sections address two areas:
    (i) The fuel tank systems of the ``baseline'' airplane (as 
originally made by the TC holder); and
    (ii) The ``actual configuration'' of the fuel tank systems of each 
affected airplane (as modified or altered after original manufacture).
    As discussed later, one purpose of this rulemaking is to make sure 
that the implementation of this proposal for wiring is aligned with the 
implementation of the Fuel Tank Safety Rule.

E. Existing Wiring Certification Regulations

    Traditionally, wire has not been looked upon as having the same 
importance to safety as the rest of the systems for which it provides 
the electrical interconnection. Whereas a particular piece of 
electrical equipment may be the focus of intense scrutiny regarding its 
design, installation, and maintenance, the wires that provide the 
electrical interconnection to that equipment have not received the same 
amount of attention, except for the wiring on engines. Additionally, in 
the past, system safety assessments usually addressed only the effect 
of a wire failure on the system itself. The safety assessments have not 
usually identified the effect of wire failures on other systems or on 
the airplane.
    Existing regulations fall short of providing specific wiring-
related requirements that we now recognize should be included. For 
example, current rules do not adequately address requirements for wires 
in system separation, safety assessments, component selection, 
component identification, protection in cargo and baggage compartments, 
and accessibility for inspection, maintenance, and repair.
    This quote from FAA Wiring Policy ANM-01-04 supports the need for 
more specific wiring information: ``The FAA expects the applicant to 
provide engineering drawings instead of merely statements such as 
`install in accordance with industry standard practices,' or `install 
in accordance with AC 43.13 [``Acceptable Methods, Techniques, and 
Practices--Aircraft Inspection and Repair''].' The FAA considers such 
statements inadequate because the standard practices cannot define the 
location or routing of the wiring to the level needed to ensure that 
new/modified wiring does not invalidate previous certification findings 
for existing airplane systems.''

III. General Discussion of the Proposal

A. Nature of the Problem

    Electrical wiring systems perform roles essential to the safety of 
the entire airplane. They distribute power throughout the airplane, 
transmit signals for control, and send data. Over time, as more 
sophisticated computerized systems have been introduced into airplane 
controls, their electrical wires, cables, and associated components 
have become increasingly important to safe flight.
    Historically, manufacturers have been required to provide 
maintenance-related information for airplane systems. However, there 
has never been a requirement for maintenance information specifically 
addressing wiring systems. Since January 28, 1981, design approval 
holders have been required to provide ICA for the airplane. ICA must be 
prepared in accordance with Appendix H to part 25. In developing ICA, 
the applicant must include certain information. This includes a 
description of the airplane and its systems, servicing information, and 
maintenance instructions, including the frequency and extent of 
inspections necessary to provide for the continued airworthiness of the 
airplane. Currently, Sec.  25.1529 includes a requirement for an FAA-
approved Airworthiness Limitations section in the ICA. This section 
must list those mandatory inspections, inspection intervals, 
replacement times, and related procedures approved under Sec. Sec.  
25.571 and 25.981. There are no requirements for specific information 
related to wiring.
    Airplanes must be continually maintained and inspected, and the 
information contained in the ICA is used as a basis for developing a 
maintenance program. Yet the examinations of large transport airplanes 
discussed earlier revealed many anomalies in electrical wiring systems 
and their components, as well as contamination by dirt and debris.
    Section 43.13(b) requires anyone performing maintenance or 
alteration to do the work in such a manner and use materials of such a 
quality that the condition of the aircraft, airframe, aircraft engine, 
propeller, or appliance worked on will be at least equal to its 
original or properly altered condition (with regard to aerodynamic 
function, structural strength, resistance to vibration and 
deterioration, and other qualities affecting airworthiness). Anyone 
performing maintenance must use methods, techniques, and practices 
prescribed in the current manufacturer's maintenance manual or ICA 
prepared by the manufacturer, or methods, techniques, and practices 
referred to in Sec.  43.13(a) as acceptable to the Administrator. 
However, current practice has shown that, when wiring is inspected as 
part of the maintenance program or following alterations, it is not 
always cleaned appropriately for the inspection being performed. 
Generally, neither FAA inspectors nor airline maintenance workers have 
been fully aware of the vulnerable and critical condition of wire and 
fuel tank systems. Little focus has been placed on the importance of 
cleaning electrical wiring during maintenance or alteration. The result 
has been to hasten the aging of wiring.
    Extensive research by the FAA, in partnership with the aviation 
industry and other government agencies, has shown that electrical 
wiring on transport category airplanes is subject to a breakdown of 
physical and functional properties. This is not just a function of 
time, but also because of many stresses on the wiring. These stressors 
include chafing, vibration, contamination, and temperature variation, 
all of which can cause cumulative damage. Each airplane maintenance 
procedure or modification, whether performed on the wiring system 
itself or on surrounding components, introduces possibilities for 
unintentional damage, changes to the previously approved wire design, 
or contamination of the wiring systems by fluids, foreign objects, and 
debris. As the aviation industry matures, there are more older 
airplanes in service, and the wiring in those airplanes has had more 
years of exposure to all these factors. Electrical wiring system 
malfunctions resulting from inadequate design, alteration, maintenance, 
inspection, and repair practices can cause incidents and accidents 
involving smoke, fire, and/or loss of function.
    Wire contamination is a major concern, especially in older 
airplanes,

[[Page 58514]]

and it occurs in many ways. Dust, dirt, and lint from airplane carpets 
and seats, lavatory waste products, hydraulic fluid, engine oil, 
corrosion prevention compounds, and galley spills all collect over 
time. Liquids can corrode connectors and other wiring components and 
degrade wire insulation. In addition, electrical current flow in the 
wiring attracts dust, dirt, and lint, and they are deposited on the 
wiring system and surrounding airplane structure by cabin airflow. 
Leakage of fluid lines and spills make the wiring grimy, so more dust, 
dirt, and lint are attracted to them.
    To fully understand why wiring system contamination is a major 
problem and a potential fire hazard that could prevent the safe 
operation of an airplane, it is necessary to understand the ``fire 
triangle'' of combustion. The fire triangle symbolizes three elements--
oxygen, heat or ignition source, and fuel. All three are necessary for 
fire to occur.
    In an airplane, oxygen, the first element of the triangle, is 
always present, because the heating and air-conditioning system must 
provide a suitable environment for passengers. Wiring can act as an 
ignition source (second element), especially if damage, such as cracked 
insulation or chafing, causes a short to ground or to another 
conductor, or if it causes arcing. Fuel for fire (third element) can be 
present in the form of dust, dirt, lint, hydraulic fluid, engine oil, 
engine fuel, and corrosion prevention compound. Eliminating or 
mitigating any of these elements will help remove the fire threat.
    For obvious reasons, oxygen cannot be eliminated from an airplane. 
Wiring systems provide critical functions, so they cannot be eliminated 
either. But their ability to act as a fire ignition source can be 
mitigated by proper design, maintenance, and repair. The easiest 
element to alleviate is fuel for fire. The improved maintenance 
requirements in this proposal, as well as the more rigorous design 
standards, are intended to address the fuel and ignition elements of 
the fire triangle of combustion.
    This NPRM also addresses the requirement that certain operators 
incorporate ICA for their fuel tank systems into their maintenance or 
inspection programs, to ensure the continued safe operation of those 
design features that minimize the potential for an ignition source in 
the fuel tank system. Although there are existing regulations that 
require these ICA, the FAA believes, based on lessons learned from SFAR 
88 and industry comments, that the existing operational rules need to 
address several issues that have arisen since they were adopted. Also, 
because there are elements in the fuel tank system that include wiring, 
those ICA could conflict with the requirements for electrical systems 
in this proposal. Additionally, the FAA believes that the compliance 
times for the regulations for those two systems, wiring systems and 
fuel tank systems, should be aligned.

B. Relationship of This Proposal to Other Aging Aircraft Initiatives

    The FAA, as part of a broader review and realignment of its Aging 
Airplane Program, has determined that certain compliance dates in 
existing rules and pending proposals could be better aligned, so that 
operators can comply more efficiently with the requirements during 
scheduled maintenance. Compliance dates could also impact our ability 
to schedule oversight programs efficiently. In addition, based on our 
review, we have determined that certain substantive changes are needed 
to improve the cost-effectiveness of these rules and proposals. 
Therefore, we have decided to revise these requirements and proposals 
and align the compliance schedules as practically as possible. Notice 
of these changes and a description of our Aging Airplane Program review 
appeared in the Federal Register on July 30, 2004 (69 FR 45936). The 
actions affected by these revisions are this proposal and three others:
     Transport Airplane Fuel Tank System Design Review, 
Flammability Reduction, and Maintenance and Inspection Requirements 
Special Federal Aviation Regulation (Fuel Tank Safety Rule) (final 
rule).
     Aging Airplane Safety (interim final rule).
     Widespread Fatigue Damage (pending proposal).
    To prevent any conflicts within this proposal, which affects fuel 
tank wiring issues, changes to the operational requirements of the Fuel 
Tank Safety Rule requiring the incorporation of fuel tank system 
maintenance and inspection tasks are proposed as part of this 
rulemaking.

C. Alternatives to Rulemaking

    Before proposing new rulemaking, the FAA must consider alternative 
ways to solve the safety issues under consideration. Following is a 
brief discussion of two of the alternatives we considered during 
deliberations on this rulemaking proposal.
    No new regulatory action. The FAA believes that the result of no 
action would be continued incidents and accidents resulting from wiring 
system failures. We would continue to address these situations 
``reactively'' on a case-by-case basis (as they occur) by issuing 
airworthiness directives. This is unacceptable from a safety 
standpoint. Improved certification regulations, inspection and 
maintenance programs, and ICA for wiring systems are needed to address 
the potential for similar problems arising on existing and future 
designs, and to ensure their long-term safety.
    Rely on voluntary compliance with the intent of the rule by 
affected parties. Some in industry have suggested simply issuing ACs to 
give guidance on the changes that need to be made. Issuing ACs would 
depend on voluntary compliance, and would not be enforceable. While 
certain members of the industry would proceed with voluntary programs, 
others would not. The use of ACs alone would ensure neither consistent 
results nor the achievement of the safety objectives of this proposal 
for the current and future fleet. Previous voluntary safety 
assessments, such as those relating to the thrust reverser and cargo 
door reviews, have been difficult to complete in a timely manner 
because they lacked enforceability. The proposed rules provide an 
enforceable means to require timely completion of the actions 
identified as necessary to address aging electrical wiring systems.

IV. Overview of Proposal

    The FAA proposes several rule changes that collectively provide a 
more proactive management of wiring systems. These changes would 
require development and implementation of ICA for wiring systems and 
subsequent incorporation of those ICA into the operators' maintenance 
or inspection program. We are also proposing changes in the 
certification rules to require, during design and installation of 
airplane systems, more attention to conditions that could compromise 
wire safety and accessibility.
    The result of these changes to the maintenance and certification 
programs would be to remove, as far as possible, sources of ignition 
and fuel for fire from the wiring systems. In addition, a new part 25 
subpart dedicated to wiring systems would be created. The current part 
25 regulations for wire would be moved into this new subpart and 
combined with new regulations. An alignment of the compliance times for 
incorporation of the wire and fuel tank ICA would also occur to enable 
a more comprehensive treatment of those ICA and accomplishment of the 
maintenance instructions at time intervals consistent

[[Page 58515]]

with typical airplane maintenance checks.
    The FAA believes that traditional ways of addressing wiring are no 
longer enough. Because wire damage or degradation can be the result of 
successive and interactive factors introduced over time, the approach 
to ensuring wiring safety must be analytical, multilayered, and 
proactive, rather than reactive. An analytical approach means assessing 
logically the possibilities for fire occurring. A multilayered approach 
means addressing multiple layers of stressors, like chafing, vibration, 
temperature change, and modification that act on wiring in succession 
or concurrently and can cause cumulative damage to an electrical 
system. A proactive approach means addressing conditions affecting safe 
flight that we know can happen--before they happen. Causes of wire 
degradation must be addressed separately and collectively, and analyzed 
in relation to the entire airplane. Based on the findings and research 
described earlier in this document, the FAA has determined that air 
carriers, operators, TC holders, supplemental type certificate (STC) 
holders, repair stations, and certificated maintenance personnel need 
to place more emphasis on wiring and fuel tank systems when performing 
maintenance and alterations. Currently, other than the visual 
inspections required by maintenance or inspection programs, maintenance 
is not normally performed on these systems unless an obvious 
discrepancy is identified. This proposal is designed to heighten 
awareness of the criticality of wiring systems and to change the 
current approach to maintaining and modifying them. Maintenance 
personnel need to be aware that current industry practice for 
maintenance and inspection of these systems is inadequate and must be 
improved, as provided by this proposal.
    The changes proposed in this NPRM were derived from the 
maintenance, inspection, design, and alteration best practices 
developed through extensive research by ATSRAC and other groups, 
including the White House Commission on Aviation Safety and 
Security,\3\ the National Science and Technology Council Committee on 
Technology Wire System Safety Interagency Working Group,\4\ the IIWG, 
and safety reviews required in accordance with SFAR 88.
---------------------------------------------------------------------------

    \3\ ``Final Report to President Clinton, February 12, 1997,'' a 
copy of which is in the docket.
    \4\ ``Review of Federal Programs for Wire System Safety,'' 
November 2000, in the docket.
---------------------------------------------------------------------------

    The following table summarizes the proposed regulatory changes that 
are discussed in detail in this section.

               Summary of Proposed Rulemaking in This NPRM
------------------------------------------------------------------------
                                 Description of
   Affected part of 14 CFR          proposal             Applies to
------------------------------------------------------------------------
1...........................  Adds the
                               abbreviation
                               ``EWIS''.
25..........................  Harmonization rules.  Applicants for type,
                                                     amended, and
                                                     supplemental type
                                                     certificates
25..........................  New subpart H         Applicants for type,
                               containing: New and   amended, and
                               revised wire-         supplemental type
                               related               certificates
                               certification
                               requirements
                               including
                               requirements to
                               develop ICA for
                               electrical wiring
                               interconnection
                               systems.
25..........................  New subpart I         Type certificate
                               containing: New       holders for large
                               requirements to       transport category
                               develop ICA for       airplanes and
                               electrical wiring     certain applicants
                               interconnection       for type, amended
                               systems in            and supplemental
                               accordance with       type certificates
                               proposed Sec.
                               25.1539 and the
                               revised Appendix H
                               for the current
                               specified fleet.
Parts 121/129...............  Requirement to        U.S. certificate
                               incorporate new       holders and foreign
                               EWIS ICA into         persons operating
                               maintenance program   U.S. registered
                               (included in new      large transport
                               subparts for          category airplanes
                               Continued
                               Airworthiness).
Parts 91/121/125/129........  New subparts (L, Y,   U.S. certificate
                               M, and B              holders and foreign
                               respectively) for     persons operating
                               Continued             U.S. registered
                               Airworthiness         large transport
                               containing parts      category airplanes.
                               121/129 EWIS ICA
                               requirements
                               (above) and:
                               Requirement
                               to incorporate fuel
                               tank ICA into
                               maintenance program.
                              
                               Redesignation of
                               other existing
                               requirements into
                               these new subparts.
------------------------------------------------------------------------

    Currently, part 25 does not have a separate subpart governing 
wiring. Certification rules that apply to wiring appear throughout the 
regulations, under the headings ``Design and Construction,'' 
``Powerplant,'' and ``Equipment.'' In some of these rules, the term 
``wiring'' is not specifically used.
    The discussion of proposed changes to part 25 is broken into four 
parts:
     Part 25 Subpart H--Electrical Wiring Interconnection 
Systems (EWIS).
     Part 25 Subpart I--Continued Airworthiness.
     Other Proposed Changes to Part 25.
     Part 25 Electrical System Harmonization Rules.
    ATSRAC recommended placing part 25 wiring-related regulations into 
one section. This change would increase the visibility of these 
regulations and facilitate a comprehensive process for the design and 
certification of wire systems. ATSRAC reviewed the current part 25 to 
identify each regulation that related to wiring, either directly or 
indirectly. Each wire-related regulation was then reviewed to determine 
if it should be moved (in whole or in part) into the proposed new 
subpart. As a result of ATSRAC's recommendations, this NPRM would 
change some existing wire requirements, add new ones, and compile all 
of them into a new subpart: subpart H of part 25.
    No single regulation was moved in its entirety to the new subpart, 
but applicable portions of regulations were moved. Some regulations 
easily lent themselves to division into wire and non-wire portions, 
while others did not. In some cases it was difficult to remove the 
wire-related portion and maintain the continuity of the existing 
regulation. In those cases, the regulation was not moved to subpart H. 
Instead, the current regulation remained in place and a new subpart H 
regulation was created to state the importance of wiring systems to the 
safe design of the system that is the subject of the existing 
regulation. Portions of some current regulations that were moved to the 
new subpart were divided and distributed among

[[Page 58516]]

several new subpart H sections to follow the logical structure of the 
new subpart. Accordingly, there is not always a one-to-one 
correspondence between the existing regulations and the new subpart H 
regulations. A table showing the correlation between proposed new 
regulations and the existing regulations can be found in APPENDIX B. 
The table in APPENDIX C compares the existing regulations to the 
proposed new ones. The APPENDIX D table shows which of the current 
wire-related rules must be changed to accommodate the new subpart and 
which will remain the same.
    Adoption of the proposed new and revised requirements and advisory 
material would help prevent future occurrences of the types of 
incidents and accidents described in this NPRM. The creation of a new 
part 25 subpart for all existing, revised, and new wire system 
certification requirements would strengthen the role of properly 
designed, installed, and maintained wire systems in increasing the 
safety of flight. It would also provide the regulatory tools to help 
ensure this outcome and locate all applicable regulations in a single 
place that is easy to reference and use.
    Certain vintage airplanes type certificated before 1958, the 
beginning of the jet age, would be excluded from the requirements of 
this proposal. They are named in paragraph (f) of Sec.  25.1805 and in 
the final paragraph of each of the proposed fuel tank and EWIS 
operating rules. There are no known reciprocating-powered transport 
category airplanes currently in scheduled passenger service, and the 
few remaining in cargo service would be excluded. Compliance is not 
required for these specific older airplanes because their advanced age 
or small numbers would likely make compliance economically impractical.

V. Section-by-Section Discussion of Proposed Rules

    The FAA proposes to add the abbreviation for electrical wiring 
interconnection systems (EWIS) to 14 CFR part 1--Definitions and 
Abbreviations. The purpose of this addition is to ensure the use of a 
common term for EWIS throughout the regulations. More detailed analysis 
of the other proposed changes and additions is outlined below.

A. Part 25 Subpart H--Electrical Wiring Interconnection Systems (EWIS)

    The proposed subpart H consists of relocated, revised, and new 
regulations about EWIS. Unless we say otherwise, our purpose in moving 
requirements to subpart H is to ensure their application to EWIS. We do 
not intend to change their legal effect in any other way.
Section 25.1701 Definition
    Proposed Sec.  25.1701 would define what constitutes an EWIS for 
the purposes of complying with the proposed subpart H requirements and 
other EWIS-related requirements of parts 25, 121, and 129.
    Current regulations do not provide a definition of a wiring system. 
Without this definition, the proposed rules could be inconsistently 
applied to various wire-related components. To completely address the 
safety issues associated with wiring systems, requirements must address 
not only the wiring itself, but also components and devices that are 
required to adequately install and identify each wire. Various 
components and devices needed to route and identify wires are critical 
in ensuring that a proper electrical interconnection is made and 
maintained.
    For the purposes of this NPRM, the term ``wire'' means bare and/or 
insulated wire used for the purpose of electrical energy transmission, 
grounding, or bonding. This includes electrical cables, coaxial cables, 
ribbon cables, power feeders, and databuses.
    A proper electrical interconnection between two or more points 
requires more than just wire. Making the connection in a manner that 
ensures both functionality and safety requires various types of 
components, of which wire is one. Therefore, a clear definition of an 
electrical interconnection is necessary. The proposed regulation 
provides this and at the same time introduces the term ``electrical 
wiring interconnection system (EWIS)'' to describe that 
interconnection. The term EWIS means any wire, wiring device, or 
combination of these, including termination devices, installed in the 
airplane for transmitting electrical energy between two or more 
termination points. The proposed regulation expands on this basic 
statement to clearly identify which wire-related components are 
included in the EWIS definition and which are not. Most wires are 
routed with other wires that make up wire bundles and cable assemblies 
(or ``looms,'' as they are sometimes called). A single wire may also be 
routed separately. The same definition of an EWIS is applied to a 
single wire or to a bundle containing hundreds of wires.
    To complete an electrical connection, various types of connectors 
are necessary. Examples are MS connectors (MS means military 
specification), D-subminiature connectors, and rack and panel 
connectors. Any connector used to complete an electrical connection is 
included in the EWIS definition. The exception to this is the mating 
connection on those devices that are excluded from the proposed 
definition. The excepted devices are addressed later in this 
discussion.
    Connector accessories fall under the definition of EWIS. Such 
accessories include, but are not limited to, backshells, strain 
reliefs, grommets, and sealing plugs. Electrical connections to devices 
such as relays, interrupters, switches, contactors, terminal blocks, 
and feed-through connectors are parts of an EWIS. For example, the 
connection device on a relay is considered part of the EWIS, but the 
relay mechanism is not, because it is a termination point. A splice can 
be considered an electrical connector because it performs the same role 
as other connection devices by providing an electrical connection 
between two or more wires. The failure of a splice or relay connection 
could create a hazardous situation by exposing bare conductors or 
impairing system functionality.
    Although a bus bar is not a ``connector'' in the traditional sense, 
it is a collector and distribution device for electrical energy and 
thus must be treated as part of an EWIS.
    Wire or wire bundles require devices to physically route and 
support them, such as clamps, brackets, standoffs, and other such 
components. These are included in the EWIS definition. Cable ties are 
included because they are used to hold multiple wires together and in 
place. The failure of one or more of these EWIS components could affect 
the ability of the wire to perform its intended function. It could 
cause collateral damage to other wires in the same or adjacent bundles 
or cause the bundle to fail in a way that would cause structural damage 
or ignite flammable material, fluid, or vapors in the area.
    Some wires must pass through pressure bulkheads, so a pressure seal 
is needed. Failure of a pressure seal could cause damage to the wires 
in the wire bundle and affect the functioning of the system they 
support. Some wire bundles use shields or braids to protect them from 
electromagnetic radiation, lightning, abrasion, and other types of 
physical damage. Failure of the shields or braid could cause, or allow, 
the wires to be damaged. It could also allow unwanted electrical energy 
to be coupled into systems and cause system malfunction. Thus, shields, 
braids, and pressure seals must be considered part of the EWIS and 
treated as such.
    Sometimes adequate physical separation distance is not possible, 
and some sort of protective sleeving may be

[[Page 58517]]

used. Since the sleeving is used to achieve separation, it must be 
considered part of the EWIS.
    Conduits are included in the proposal because they are used to 
provide protection for wires as well as provide physical separation. 
Conduits that have electrical termination for bonding are considered 
part of an EWIS because the failure of the bonding could create a 
hazardous situation.
    The definition of an EWIS includes labels or other means used for 
identification. This supports the proposed Sec.  25.1711 requiring new 
identification criteria for wires and other EWIS components. Discussion 
of the proposed labeling requirements appears under the heading for 
Sec.  25.1711.
    The proposed regulation does not cover portable, carry-on, or other 
electrical equipment not certified for installation on the airplane 
under part 25. Examples of items not included are laptop computers and 
portable audio and/or video or other consumer devices typically carried 
on-board by passengers for personal use. Increasingly, flight and cabin 
crew are using laptop computers in the performance of their duties. As 
stated, laptops are not part of the EWIS definition, but any electrical 
connection used to support power and/or signal transmission that is 
part of the airplane TC, and that is used for the laptop or other 
carry-on items, is covered by the proposed definition.
    The proposed EWIS definition does not cover fiber optic cable 
because fiber optic cable does not transmit electrical energy. But 
since fiber optics can provide functions (for example, data 
transmission) similar to those provided by wire, it is being expressly 
eliminated from the EWIS definition to avoid confusion.
    The proposed definition excludes electrical wiring interconnection 
system components inside avionics equipment (high-frequency 
communication radio or flight data recorder, for instance), or the 
mating electrical connectors mounted on that equipment. Such equipment 
is produced by various manufacturers for use on a broad range of 
airplane models and is designed and built to various performance and 
environmental specifications. Environmental testing, either by means of 
RTCA (Radio Technical Commission for Aeronautics) Document No. RTCA DO-
160, EUROCAE 55 specification (specification of the European 
Organization for Civil Aviation Equipment), or other environmental 
qualification procedures approved by the FAA, ensures that the EWIS 
contained within avionics equipment is robust and well suited for the 
airborne environments in which it will be operated.
    This proposal also does not apply to miscellaneous electrical 
equipment if that equipment has been adequately qualified to 
environmental conditions and testing procedures approved by the FAA, 
unless that equipment is specifically included in the proposed Sec.  
25.1701 as discussed in the following paragraph.
    The definition of EWIS includes electrical wiring interconnection 
system components inside shelves, panels, racks, junction boxes, 
distribution panels, back-planes of equipment racks including circuit 
board back-planes, and wire integration units. We have included the 
components in this type of equipment because it, unlike avionics 
equipment, is typically designed and made for a particular airplane 
model or series of models. The same requirements that apply to airplane 
EWIS components must also be applied to the components inside that 
equipment. Avionics components must be sent back to their manufacturer 
or a specialized repair shop for service. But this type of equipment is 
maintained, repaired, and modified by the same personnel who maintain, 
repair, and modify the EWIS in the rest of the airplane. In an 
electrical distribution panel system, for example, separation must be 
designed and maintained within the panel just as in the EWIS leading up 
to that panel. Identification of components inside the panel is just as 
important as for those outside the panel since the wiring inside the 
panel is treated much the same. Also, while this type of equipment is 
designed for its intended function and is manufactured and installed to 
the same standards as other EWIS, it is typically not qualified to an 
environmental standard such as RTCA DO-160.
Section 25.1703 Function and Installation: EWIS
    Proposed Sec.  25.1703 would require that applicants select EWIS 
components that are of a kind and design appropriate to their intended 
function. Factors such as the components' design limitations, 
functionality, and susceptibility to arc tracking and moisture must be 
considered when selecting EWIS components.
    Section 25.1301 requires that each item of installed equipment be 
of a kind and design appropriate to its intended function, be labeled 
(identified), be installed according to any limitations specified for 
it, and function properly when installed. This is a general ``catch-
all'' regulation applicable to equipment and systems certified under 
subpart F. Because of its generality and the fact that the FAA has not 
published any advisory circular for this rule, Sec.  25.1301 has not 
been applied in a standardized way. Currently, Sec.  25.1301 is 
applicable to wire and its associated components but it does not 
provide sufficient wire-specific requirements to ensure proper function 
and installation of EWIS. It does not adequately cover all factors that 
need to be considered when selecting, identifying, and installing 
wiring components.
    The requirements of Sec.  25.1301 are the basis for the new Sec.  
25.1703, but those requirements are supplemented by new ones. 
Requirements from other existing sections are also moved into the new 
regulation, so that the proposed rule would specifically apply to EWIS 
components. Adoption would ensure that the selection of wires and other 
EWIS components, and their installation, are carried out in a safe, 
consistent, and standardized manner.
    Section 25.1703(a)(1) would require that each EWIS component be of 
a kind and design appropriate to its intended function. While Sec.  
25.1301(a) contains the same requirements, Sec.  25.1703(a)(1) is 
specific to EWIS components. In this context, the requirement means 
that components must be qualified for airborne use, or otherwise 
specifically assessed as acceptable for their intended use. To be 
``appropriate'' means that the equipment is used in a manner for which 
it was designed. For example, a wire rated at 150 degrees Celsius would 
not be appropriate for installation in an airplane zone where the 
temperature exceeds 150 degrees Celsius. Wire and other components made 
for household or consumer products use would not be appropriate for 
airborne use because they are manufactured for the consumer market and 
not for use in an airborne environment. Exceptions to this would be 
wire or other consumer components shown to comply with all the 
applicable airworthiness requirements of part 25. In the past this 
showing of compliance has proven to be difficult because manufacturers 
of consumer products have been reluctant to modify their designs to 
accommodate aviation use. Aviation use of consumer products represents 
too small a market.
    Other factors that must be considered for EWIS component selection 
are mechanical strength, voltage drop, required bend radius, and 
expected service life. Expected service life means the expected service 
lifetime of the EWIS. This is not normally less than the expected 
service life of the aircraft structure. If the expected service life 
requires that all or some of the EWIS components be replaced at certain

[[Page 58518]]

intervals, then these intervals must be specified in the ICA as 
required by Sec.  25.1529.
    Section 25.1703(a)(2) requires that EWIS components be installed 
according to their limitations. As used here, limitations means the 
design and installation requirements of the particular EWIS component. 
Examples of EWIS component limitations are maximum operating 
temperature, degree of moisture resistance, voltage drop, maximum 
current-carrying capability, and tensile strength. Section 25.1301(c) 
contains that requirement, but fails to specifically address the unique 
characteristics of EWIS. EWIS component selection and installation 
design must take into account various environmental factors including, 
but not limited to, vibration, temperature, moisture, exposure to the 
elements or chemicals (de-icing fluid, for instance), insulation type, 
and type of clamp. For example, wire bundle adhesive clamps are known 
to work loose during aircraft operation. Attention must be given to the 
selection of and methods of affixing this type of wire bundle support 
and it must be shown that this type of clamp is appropriate for the 
environment in which it will be used.
    Section 25.1703(a)(3) would require that EWIS function properly 
when installed. This is the same requirement as Sec.  25.1301(d). 
However, the Sec.  25.1301(d) requirement is so general that it is 
applied in a nonstandardized manner. Sometimes the term ``function 
properly when installed'' has been interpreted to mean that even non-
safety-related functions of a given system must function in the manner 
for which it was designed. The key word in understanding the intent of 
this proposed section is ``properly,'' as that relates to airworthiness 
of the airplane in which the electrical wiring interconnection systems 
are installed. For an EWIS component to function properly means that it 
must be capable of safely performing the function for which it was 
designed. For example, the fact that an airplane's in-flight 
entertainment (IFE) system fails to deliver satisfactory picture or 
sound quality is not what the term ``properly'' refers to and is not a 
certification issue. However, the failure of an EWIS component has the 
potential for being a safety hazard whether it is part of a safety-
related system or an IFE system. Therefore, EWIS components must always 
function properly when installed, no matter what system they are part 
of. The guidance material being prepared to accompany the proposed 
subpart H, AC 25,17XX, ``Certification of Electrical Wiring 
Interconnection Systems on Transport Category Airplanes,'' will clarify 
these distinctions.
    Section 25.1703(a)(4) is a new requirement to ensure that EWIS 
components be designed and installed so mechanical strain is minimized. 
This means the EWIS installation must be designed such that strain on 
the wires would not be so great as to cause wire or other components to 
fail. This requirement would ensure that adequate consideration is 
given to mechanical strain when selecting wire and cables, clamps, 
strain reliefs, stand-offs, and other devices used to route and support 
the wire bundle.
    Proposed Sec.  25.1703(b) would require that selection of wires for 
installation takes into account known characteristics of different wire 
types in relation to each specific application, to minimize risk of 
damage. It is important to select the aircraft wire type whose 
construction matches the application environment. The wire type 
selected must be constructed for the most severe environment likely to 
be encountered in service. Among other things, the proposed section 
would ensure that insulation types susceptible to arc tracking be used 
only in environments that will minimize the likelihood of that 
phenomenon. Arc tracking is a phenomenon in which a conductive carbon 
path forms across an insulating surface. A breach in the insulation 
allows arcing. The arcing carbonizes the insulation. The carbon residue 
is electrically conductive. The carbon path then provides a short 
circuit path through which current can flow. This can occur on either 
dry or wet wires. Certain types of wire insulation are more susceptible 
to arc tracking than others. Wire insulated with aromatic polyimide is 
one type that is susceptible to arc tracking. While this type of 
insulation is well suited for use in very low or high temperature 
environments, it generally should not be used in areas of an airplane 
prone to excessive moisture or vibration, such as those areas 
designated as severe wind and moisture problem (SWAMP) areas without 
taking into account this insulation property's unique characteristics. 
Installations exposed to vibration and constant flexing in a moisture-
prone area would need wire type suitable for that environment. Proposed 
Sec.  25.1703(c) would require that design and installation of the main 
power cables allow for a reasonable degree of deformation and 
stretching without failure. This requirement now resides in Sec.  
25.869(a)(3).
    Proposed Sec.  25.1703(d) requires that EWIS components located in 
areas of known moisture build-up be adequately protected to minimize 
moisture's hazardous effects. This is to ensure that all practical 
means are used to ensure damage from fluid contact with components does 
not occur. Wires routed near a lavatory, galley area, hydraulic lines, 
severe wind and moisture problem areas such as wheel wells and wing 
trailing edges, and any other area of the airplane where moisture 
collection could be a concern must be adequately protected from 
possible adverse effects of exposure to the types of moisture in these 
areas.
    If a TC includes subpart H in its certification basis, the TC 
holder would have to show compliance with the proposed EWIS 
requirements. For future modifications of those TCs, use of the same 
design practices as those used by the TC holder will enable the 
modifier to substantiate compliance with the subpart H requirements 
based on a comparison with the TC holder's methods. If modifiers choose 
to deviate from those design practices, they would have to substantiate 
compliance independently. They would also have to consider the design 
practices used by the TC holder in order to justify their own choice of 
components.
    In summary, these new rules would require the designer and 
installer to be careful in wire type choices, system design, and 
installation design. The existing Sec.  25.1301 would be amended to 
contain a reference to Sec.  25.1703 for EWIS component requirements.
Section 25.1705 System Safety: EWIS
    Proposed Sec.  25.1705 would require applicants to perform a system 
safety assessment of the EWIS. The safety assessment must consider the 
effects that both physical and functional failures of EWIS would have 
on the airplane's safety. Based on that safety assessment, it must be 
shown that each EWIS failure considered to be hazardous is extremely 
remote. Each EWIS failure considered to be catastrophic must be shown 
to be extremely improbable and not result from a single failure.
    The current regulation requiring system safety assessments is Sec.  
25.1309. But current Sec.  25.1309 practice does not lead to the type 
of analysis that fully ensures all EWIS failure conditions affecting 
airplane-level safety are considered. This is because the current Sec.  
25.1309(a) only covers systems and equipment that are ``required by 
this subchapter,'' and wiring for nonrequired systems is sometimes 
ignored. The current safety analysis requirements of Sec.  25.1309(b) 
and (d) have not always been applied to wire associated with the 
airplane systems that are covered by the

[[Page 58519]]

same rule. When they are, there is evidence of inadequate and 
inconsistent application. This is especially true for miscellaneous 
electrical equipment that is not required, such as IFE systems. 
Traditional thinking about these nonrequired systems has been that, 
since they are not required, and the function they provide is not 
necessary for the safety of the airplane, their failure could not 
affect the safety of the airplane. This is not a valid assumption 
because failure of an electrical wire can have hazardous or even 
catastrophic results regardless of the system it is associated with. 
Wire failure can cause serious physical and functional damage whether 
the wire or other EWIS components are associated with an autoland 
system or an IFE system. An example of this is arcing from a shorted 
wire cutting through flight control cables.
    The Aviation Rulemaking Advisory Committee (ARAC), based on the 
work of its System Design and Analysis Harmonization Working Group, has 
made recommendations to the FAA for changes to the current Sec.  
25.1309. We are evaluating those recommendations. (A copy of those 
recommendations has been placed in the docket for reference.) We have 
considered the ARAC recommendations in developing the proposed Sec.  
25.1705.
    One of the factors we considered in developing the proposed Sec.  
25.1705 is that the proposed ARAC revisions to Sec.  25.1309 would 
exempt certain airplane systems, including the EWIS components 
associated with those systems, from having to comply with its 
requirements. Specifically, ARAC recommends that jamming of flight 
control surfaces or pilot controls covered by Sec.  25.671(c)(3) be 
exempt from the requirements of Sec.  25.1309. Single failures covered 
by Sec.  25.735(b)(1) and the failure effects covered by Sec. Sec.  
25.810(a)(1)(v) and 25.812 would also be excepted from the revision to 
Sec.  25.1309(b) recommended by ARAC. This includes wiring or other 
EWIS components associated with those systems. In part, proposed Sec.  
25.1705 would ensure coverage of the EWIS associated with those 
systems.
    There are many examples of inadequate EWIS designs that have later 
been determined to be unsafe. Adoption of proposed Sec.  25.1705 would 
help ensure that those unsafe design practices are not repeated in the 
future by requiring that EWIS failure conditions affecting airplane-
level safety are fully considered. The current Sec.  25.1309 does not 
provide that assurance.
    The FAA has issued over 100 wire-related airworthiness directives 
(AD) since 1998. Over 50 of those were issued since 1999 to correct 
wiring deficiencies on the Model MD-11 airplane as delivered by the 
manufacturer. Airplanes as delivered from all transport category 
airplane manufacturers have been the subject of mandatory corrective 
action to correct safety-related wiring problems.
    Similarly, the FAA has issued many ADs to correct unsafe EWIS 
installations because of postdelivery modifications. One example of 
this involves the IFE system installed on the Swissair MD-11 airplane 
that crashed off the coast of Nova Scotia and was discussed previously 
in this document. That modification is a clear case of not considering 
the effect that EWIS failures can have on airplane safety. The airplane 
was modified using the supplemental type certification process to add 
the IFE system. That system contained roughly 750 separate electronic 
boxes and was installed without an adequate safety assessment per Sec.  
25.1309. Although this IFE system consumed relatively large amounts of 
electrical power and its components and wiring were distributed 
throughout, below, and above the entire passenger cabin, the applicant 
did not thoroughly address the safety implications of routing the 
system wire in the same bundles as wire from other airplane systems, 
thus raising a concern for common cause failure to multiple essential 
systems. In many instances the applicant could not identify what 
airplane systems were associated with the wire in the bundles modified 
to route the IFE wiring. With the adoption of the proposed Sec.  
25.1705, this IFE system, as designed and installed on an airplane with 
the proposed subpart H in its type certification basis, would be 
subjected to a more rigorous safety assessment that would identify any 
inappropriate routing and force a design change.
    Many other examples of type design modifications provide evidence 
that modifiers do not always give due consideration to the impact on 
safety that installation of a new or modified system may have. 
Modifiers continue to route the EWIS needed for modifications with, or 
in close proximity to, wiring from other airplane systems without 
identifying protection mechanisms for those systems. The current Sec.  
25.1309 and revisions to it recommended by ARAC do not contain 
sufficient requirements to ensure such modifications maintain the level 
of safety intended by the regulation.
    Accordingly, a more comprehensive and specific safety assessment 
regulation for EWIS is necessary. The objective of the proposed Sec.  
25.1705 is to focus attention on EWIS and the safety issues associated 
with them by using the concepts of Sec.  25.1309 to provide for 
consistent use of a more thorough and structured analysis of aircraft 
wiring and its associated components.
    The integrated nature of wiring and the potential severity of 
failures demand a more structured safety analysis approach than that 
traditionally used under the current, or the ARAC's proposed revision 
to, Sec.  25.1309. There are more failure modes that need to be 
addressed than have been addressed previously with traditional analyses 
(arcing events that occur without tripping circuit breakers, resulting 
in complete wire bundle failures and fire; or wire bundle failures that 
lead to structural damage, for example). Current Sec.  25.1309 system 
safety assessments typically evaluate effects of wire failures on 
system functions. But they have not considered physical wire failure as 
a cause of the failure of other wires within the EWIS. The traditional 
assessments look at external factors like rotor burst, lightning, and 
hydraulic line rupture, but not at internal factors, like a single wire 
chafing or arcing event, as the cause of the failure of functions 
supported by the EWIS. Compliance with the proposed Sec.  25.1705 would 
require addressing those failure modes at the airplane level. This 
means that EWIS failures would need to be analyzed to determine what 
effect they would have on the safe operation of the airplane.
    The proposed rule language is consistent with Sec.  25.1309 and is 
meant to work in conjunction with the Sec.  25.1309 assessments 
performed on airplane systems. It would require that the probability of 
a hazardous failure condition be extremely remote and that the 
probability of a catastrophic failure condition be extremely improbable 
and not result from a single failure. The terminology and meaning of 
the classifications of EWIS failure conditions are identical to those 
proposed by ARAC in August 2002. The proposed AC produced by that 
working group discussing this, titled ``System Design and Analysis,'' 
is in the docket for this NPRM. The following table identifies and 
explains the failure condition terms.

[[Page 58520]]



                  Classification of Failure Conditions
------------------------------------------------------------------------
               Term                              Explanation
------------------------------------------------------------------------
No Safety Effect..................  Failure conditions that would have
                                     no effect on safety; for example
                                     failure conditions that would not
                                     affect the operational capability
                                     of the airplane or increase
                                     flightcrew workload.
Minor.............................  Failure conditions that would not
                                     significantly reduce airplane
                                     safety, and involve flightcrew
                                     actions that are well within their
                                     capabilities. Minor failure
                                     conditions may include, for
                                     example:
                                     a slight reduction in
                                     safety margins or functional
                                     capabilities;
                                     a slight increase in
                                     flightcrew workload, such as
                                     routine flight plan changes; or
                                     some physical discomfort to
                                     passengers or cabin crew.
Major.............................  Failure conditions that would reduce
                                     the capability of the airplane or
                                     the ability of the flightcrew to
                                     cope with adverse operating
                                     conditions to the extent that there
                                     would be, for example:
                                     a significant reduction in
                                     safety margins or functional
                                     capabilities;
                                     a significant increase in
                                     flightcrew workload or in
                                     conditions impairing flightcrew
                                     efficiency;
                                     discomfort to the
                                     flightcrew; or
                                     physical distress to
                                     passengers or cabin crew, possibly
                                     including injuries.
Hazardous.........................  Failure conditions that would reduce
                                     the capability of the airplane or
                                     the ability of the flightcrew to
                                     cope with adverse operating
                                     conditions to the extent that there
                                     would be, for example:
                                     a large reduction in safety
                                     margins or functional capabilities;
                                     or
                                     physical distress or
                                     excessive workload such that the
                                     flightcrew cannot be relied upon to
                                     perform their tasks accurately or
                                     completely; or
                                     serious or fatal injuries
                                     to a relatively small number of
                                     persons other than the flightcrew.
Catastrophic......................  Failure conditions that would result
                                     in multiple fatalities, usually
                                     with the loss of the airplane.
                                     (Note: A catastrophic failure
                                     condition was defined differently
                                     in previous versions of Sec.
                                     25.1309 and in accompanying
                                     advisory material as ``a failure
                                     condition that would prevent
                                     continued safe flight and
                                     landing.'')
------------------------------------------------------------------------

    The proposed Sec.  25.1705 would complement the Sec.  25.1309 
assessments by raising the quality of the safety assessment with 
respect to EWIS failures that would not be identified using the 
traditional methods of compliance with Sec.  25.1309. The analysis 
required to show compliance with the proposed regulation is based on a 
qualitative approach to assessing EWIS safety as opposed to a numerical 
probability-based quantitative analysis. The intent is not to examine 
each individual wire and its relation to other wires, but rather to 
ensure that there are no unacceptable hazards to the airplane. This 
does not preclude the possibility that, should the analysis identify a 
failure in a given wire bundle or component(s) that may lead to a 
catastrophic failure condition, the design mitigation process may lead 
to performing a complete analysis of each wire in the relevant bundle.
    The type of analysis used to show compliance with the proposed 
Sec.  25.1705 can vary depending on the knowledge of the designers or 
modifiers of an EWIS. As stated earlier, it is important that there is 
thorough knowledge of what systems and functions the other wires in the 
same and surrounding bundles support. In the case of a post-TC 
modification, without this information it would be impossible to state 
that the modified system could not fail in a way that would cause a 
hazardous or catastrophic event. If this information is not available 
to the modifier, then the EWIS system must be designed to accommodate 
this lack of knowledge. This would typically mean that wire being added 
for the modification would need to be routed separately from existing 
airplane wiring.
    Flowchart 1 and Flowchart 2, contained in Appendix E of this 
notice, illustrate the type of analysis necessary to show compliance 
with the proposed Sec.  25.1705. Two separate cases are considered. 
Flowchart 1 is applicable to pre-type-certification work and to TCs and 
STCs when the modifier has all the data necessary to perform the 
analysis. If the analysis is conducted according to this flowchart, the 
available data must include identification of systems supported by the 
EWIS under consideration for modification and the functions associated 
with them. The original aircraft manufacturer has most of this data and 
would normally follow the Flowchart 1 method. However, this may not 
always be the case when the manufacturer modifies an airplane that has 
been previously modified by another party.
    The analysis depicted in Flowchart 2 would apply to modifiers for 
post-TC modification who cannot identify the systems or functions 
contained in EWIS being considered for modification.
    In both analyses, EWIS functional and physical failures are 
addressed. It is the physical portion that has been neglected in past 
system safety analyses. The proposed regulation would require an 
applicant to identify any physical failure of EWIS that can cause 
damage to co-located EWIS or other surrounding systems or structure, or 
injury to people. Once those physical failures are identified, their 
severity can be determined and design mitigation strategies can be 
developed and applied. The process is repeated until all known unsafe 
features are eliminated. The difference between the processes 
identified in the two flowcharts is that in Flowchart 1, all the 
systems and associated functions whose wires are in a bundle are known. 
In Flowchart 2, new wire is routed separately from existing wire. 
Otherwise, the analysis is the same.
    In summary, the need for this new regulation is shown by experience 
on the part of the FAA and other governmental regulatory authorities 
and by service histories. Many wire-related incidents and accidents 
have occurred. Post-TC modifications have repeatedly introduced wiring 
safety problems. Airplane manufacturers have delivered airplanes that 
have wiring problems when they leave the factory, or such problems have 
later developed in service, as evidenced by resulting mandatory 
corrective actions. Adoption of this proposal would ensure that such 
problems are fully considered and addressed as part of the type 
certification process.
Section 25.1709 System Separation: EWIS
    Proposed Sec.  25.1709 would require applicants to design EWIS with 
appropriate separation to minimize the possibility of hazardous effects 
upon the airplane or its systems.
    Safe operation of airplanes depends in part on the safe transfer of 
electrical energy, a function provided by airplane EWIS. If an EWIS 
failure should occur, the separation between the failed EWIS and other 
EWIS and airplane systems

[[Page 58521]]

plays an important role in ensuring that any hazardous effects of the 
failure are mitigated to an acceptable level. Thus, it is vital to 
design and install wiring systems with adequate separation from those 
systems whose interaction with the wire could create hazardous effects. 
Currently, part 25 certification rules do not adequately address wire 
system separation. The rules currently used to require system 
separation are Sec.  25.1353(a), (b), and (c), but service experience 
has shown that compliance with these requirements, with regard to 
wiring systems, has not always been adequate. This is due in part to 
their lack of specific wording about which wiring systems are covered 
and which systems those wires are meant to be separated from. The 
proposed rule corrects these inadequacies by stating specifically that 
it applies to each EWIS on the airplane, and mandating specific 
separation requirements for certain airplane systems known to have 
potential for creating a hazardous condition. The term ``hazardous 
condition'' in this proposed rule is used in a different context than 
it is used in the proposed Sec.  25.1705. Proposed Sec.  25.1705 uses 
the terms ``hazardous'' and ``catastrophic'' in the context of 
assigning a numerical probability to failures that can cause a failure 
condition. Hazardous failure conditions and catastrophic failure 
conditions are defined in the discussion of the proposed Sec.  25.1705. 
In proposed Sec.  25.1709, the term hazardous condition means that the 
applicant must perform a qualitative design assessment of the installed 
EWIS. This assessment would involve using reasonable engineering and 
manufacturing judgment and assessing relevant service history to decide 
whether an EWIS, any other type of system, or any structural component 
could fail in such a way that a condition affecting the airplane's 
ability to continue safe operation could result. A numerical 
probability assessment may still be required under the requirements of 
the proposed Sec.  25.1705 if the airplane-level functional hazard 
assessment identifies failures that could affect safe operation of the 
airplane.
    To illustrate the type of assessment required by proposed Sec.  
25.1709, consider the following simple example involving the use of 
wire bundle clamps. Clamps are used to secure a wire bundle to 
structure in order to hold the bundle in place and route the bundle 
from one location to another along a predetermined path. An airplane 
manufacturer, using the criteria contained in the proposed advisory 
material for 25.1709, determines that a 2-inch separation from 
hydraulic lines is necessary. The manufacturer further decides that one 
clamp every 10 inches is needed to maintain that separation. However, 
there is one localized area where a single clamp failure would 
potentially create a hazard. This is because the area in question is a 
high vibration, high temperature area, subject to exposure to moisture. 
So the clamp in this particular area is exposed to severe environmental 
conditions that could lead to its accelerated degradation. The 
manufacturer decides that using just a single clamp every 10 inches in 
this area would not suffice to preclude a hazardous event. The 
manufacturer prescribes use of double clamps every 10 inches in that 
area.
    The requirements of proposed Sec.  25.1709 do not preclude use of 
valid component failure rates if the applicant chooses to use a 
probability argument in addition to the design assessment to 
demonstrate compliance. It also does not preclude the FAA from 
requiring such an analysis if the applicant cannot adequately 
demonstrate that hazardous conditions will be prevented solely by using 
the qualitative design assessment.
    As used in the proposed rule, the term ``separation'' is a measure 
of physical distance. The purpose of separation is to prevent hazards 
of arcing between wires in a single bundle, between two or more 
bundles, or between an electrical bundle and a non-electrical system or 
structure. In some cases, the proposal would allow separation to be 
achieved with a barrier or other means shown to be at least equivalent 
to the necessary physical distance. However, distance separation is 
preferred because service experience shows that use of barriers such as 
conduits can cause wire damage or lead to maintenance errors. In some 
cases, wire bundle sleeving is used to provide separation, although the 
sleeving itself is susceptible to the same types of damage as wire 
insulation.
    Determining the necessary amount of physical separation distance is 
essential. However, the proposed rule does not mandate specific 
separation distances because each system design and airplane model can 
be unique, and because manufacturers have differing design standards 
and installation techniques. Instead it requires that the chosen 
separation be adequate so that an EWIS component failure will not 
create a hazardous condition. The following factors must be considered 
when determining the separation distance:
    (1) The electrical characteristics, amount of power, and severity 
of failure condition of the system functions performed by the signals 
in the EWIS and adjacent EWIS.
    (2) Installation design features, including the number, type, and 
location of support devices along the wire path.
    (3) The maximum amount of slack wire resulting from wire bundle 
build tolerances and other wire bundle manufacturing variabilities.
    (4) Probable variations in the installation of the wiring and 
adjacent wiring, including position of wire support devices and amount 
of wire slack possible.
    (5) The intended operating environment, including amount of 
deflection or relative movement possible and the effect of failure of a 
wire support or other separation means.
    (6) Maintenance practices as defined by the airplane manufacturer's 
standard wiring practices manual and the ICA required by Sec.  25.1529 
and proposed Sec.  25.1739.
    (7) The maximum temperature generated by adjacent wire/wire bundles 
during normal and fault conditions.
    The FAA recognizes that some airplane models may have localized 
areas where maintaining the minimum physical separation distance is not 
feasible. In those cases, other means of ensuring equivalent minimum 
physical separation may be acceptable, if testing or analysis 
demonstrates that safe operation of the airplane is not jeopardized. 
The testing or analysis program must be conservative and consider the 
worst possible conditions.
    Paragraphs (a), (b), (c), and (d) of proposed Sec.  25.1709 contain 
EWIS-related requirements derived from the existing regulations 
applying to electrical power generation systems and electrical 
equipment and installations (Sec. Sec.  25.1351 and 25.1353). Section 
25.1351 does not need any revision to support the proposed Sec.  
25.1709, but Sec.  25.1353 is amended to reference Sec.  25.1709.
    The proposed requirements of Sec.  25.1709(a) were derived from 
existing Sec.  25.1353(a). While the requirements of Sec.  25.1353(a) 
are retained, the portion of that requirement applicable to wiring has 
been moved to the proposed Sec.  25.1709(a). Further clarification of 
the requirement is also included in the proposal. Section 25.1353(a) 
states ``* * * wiring must be installed so that operation of any one 
unit or system of units * * *.'' Proposed section 25.1709(a) expands on 
the term ``operation'' to state that it means ``operation under normal 
and failure conditions as defined by Sec.  25.1309.''
    Proposed section 25.1709(b) would require that each EWIS be 
designed and

[[Page 58522]]

installed so that any electrical interference likely to be present in 
the airplane will not result in hazardous effects on the airplane or 
its systems. This proposed requirement is based on new text recently 
added to Sec.  25.1353(a) to harmonize part 25 with the existing text 
of the JAA JAR 25.1353(a).\5\ The text of JAR 25.1353(a) requires that 
any electrical interference likely to be present in the airplane must 
not result in hazardous effects on the airplane or its systems except 
under extremely remote conditions. The proposed Sec.  25.1709(b) is 
recognition of the fact that electrical interference can be introduced 
into airplane systems and wiring by coupling between electrical cables 
or between cables and coaxial lines, as well as by the other equipment 
that is the subject of Sec.  25.1353(a). The proposed requirement does 
not adopt the JAR clause ``except under extremely remote conditions.'' 
This is because the intent of the requirement is not to require a 
numerical probability assessment of the likelihood of electrical 
interference or its consequences as described previously. Rather it is 
meant to convey that under failure conditions that may be caused by 
electrical inference, the resultant effects should not be such as to 
prevent continued safe flight of the airplane.
---------------------------------------------------------------------------

    \5\ The JAA is the Joint Aviation Authority of Europe and the 
JAR is its Joint Aviation Requirements, the equivalent of our 
Federal Aviation Regulations. In the time since these proposals were 
developed, in 2003, the European Aviation Safety Agency (EASA) was 
formed. EASA is now the principal aviation regulatory agency in 
Europe, and we intend to continue to work with them to ensure our 
proposal is also harmonized with its Certification Specifications 
(CS). But since the harmonization efforts involved in developing 
this proposal occurred before EASA was formed, it was the JAA that 
was involved with them. So while the JAR and CS are essentially 
equivalent, and in the future we will be focusing on the CS, it is 
the JAR that will be referred to in the historical background 
discussions in this proposal.
---------------------------------------------------------------------------

    Proposed section 25.1709(c) contains the wire-related requirements 
of the current Sec.  25.1353(b). These requirements have been expanded 
to add that not only wires and cable carrying heavy current are 
covered, but their associated EWIS components are covered as well. The 
proposal prescribes that any required physical separation must be 
achieved either by separation distance or by barrier or other means 
shown to be at least equivalent to an adequate separation distance.
    Proposed section 25.1709(d) contains wire-related requirements of 
existing Sec. Sec.  25.1351(b)(1) and (b)(2) and would introduce 
additional requirements. To show compliance with Sec.  25.1709(d), EWIS 
components associated with the generating system must be considered 
with the same degree of attention as other components of the system, 
such as the electrical generators. The proposal prescribes that any 
required physical separation must be achieved either by separation 
distance or by a barrier or other means shown to be at least equivalent 
to an adequate separation distance. Paragraph (d)(1) would introduce a 
requirement to prohibit the airplane's independent electrical power 
sources from sharing a common ground terminating location. Paragraph 
(d)(2) would prohibit the airplane's static grounds from sharing a 
common ground terminating location with any of the airplane's 
independent electrical power sources. These two new requirements would 
help to ensure the independence of separate electrical power sources 
and to prevent introduction of unwanted interference into airplane 
electrical power systems from other airplane systems.
    Paragraphs (e), (f), (g), and (h) of proposed Sec.  25.1709 contain 
EWIS-related requirements from Sec.  25.1353(d)(3). These paragraphs 
contain specific separation requirements for the airplane's fuel, 
hydraulic, oxygen, and waste/water systems. They require that EWIS have 
adequate separation from those systems except to the extent necessary 
to provide any required electrical connection to them. These paragraphs 
require that EWIS be designed and installed with adequate separation so 
a failure of an EWIS component will not create a hazardous condition 
and any leakage from those systems (i.e., fuel, hydraulic, oxygen, 
waste/water) onto EWIS components will not create a hazardous 
condition. The proposed requirements recognize the potential 
catastrophic hazard that could occur should an arcing fault ignite a 
flammable fluid like fuel or hydraulic fluid. An arcing fault has the 
potential to puncture a line associated with those systems if adequate 
separation is not maintained. If there is leakage from one of those 
systems and an arcing event occurs, fire or explosion could result. 
Similarly, leakage from the water/waste system can cause damage to EWIS 
components and adversely affect their integrity. An EWIS arcing event 
that punctures a water or waste line could also introduce fluids into 
other airplane systems and create a hazardous condition.
    To prevent chafing, jamming, or other types of interference or 
other failures that may lead to loss of control of the airplane, EWIS 
in general and wiring in particular must be physically separated from 
flight or other control cables. Mechanical cables have the potential to 
cause chafing of electrical wire if the two come into contact. This can 
occur either through vibration of the EWIS and/or mechanical cable or 
because of cable movement in response to a system command. A mechanical 
cable could also damage other EWIS components, such as a wire bundle 
support, in a way that would cause failure of that component. Also, if 
not properly designed and installed, a wire bundle or other EWIS 
component could interfere with movement of a mechanical control cable 
by causing jamming or otherwise restricting the cable's movement. An 
arcing fault could damage or sever a control cable, or a control cable 
failure could cause damage to EWIS if not adequately separated. 
Therefore, proposed paragraph (i) would require an adequate separation 
distance or barrier between EWIS and flight or other mechanical control 
systems cables and their associated system components. It would further 
require that failure of an EWIS component must not create a hazardous 
condition and that the failure of any flight or other mechanical 
control systems cables or systems components must not damage EWIS and 
create a hazardous condition.
    EWIS in general and wiring in particular must be routed away from 
high-temperature equipment, hot air ducts, and hydraulic, fuel, water, 
and other lines. There must be adequate separation distance in order to 
prevent damage to the EWIS caused by extreme temperatures and so that 
an EWIS failure will not damage the equipment, ducts, or lines. High 
temperatures can deteriorate wire insulation and other parts of EWIS 
components, and if the wire or component type is not carefully 
selected, this deterioration could lead to wire or component failure. 
Similarly, should an arcing event occur, the arc could penetrate a hot 
air duct or line and allow the release of high pressure, high 
temperature air. Such a release could damage surrounding components 
associated with various airplane systems and potentially lead to a 
hazardous situation. Paragraph (j) would require that EWIS be designed 
and installed with an adequate separation distance or barrier between 
the EWIS components and heated equipment, hot air ducts, and lines.
    The needed reliability of some airplane systems, such as an 
autoland system, requires that independent, redundant systems be used. 
Loss of one channel of a redundant system would not decrease the 
ability to continue safe operation. However, if both channels of a two-
channel system were lost because of a common failure, the results could 
be catastrophic. To maintain the independence of redundant systems and

[[Page 58523]]

equipment so that safety functions required for safe operation are 
maintained, adequate separation and electrical isolation between these 
systems must be ensured. Paragraph (k) would require that EWIS 
associated with any system that requires redundancy to meet 
certification requirements be separated with an adequate separation 
distance or barrier.
    Paragraph (l) of proposed Sec.  25.1709 would require that EWIS be 
designed and installed so they are adequately separated from aircraft 
structure and protected from sharp edges and corners. The purpose of 
this proposal is to minimize the potential for abrasion/chafing, 
vibration damage, and other types of mechanical damage. Such protection 
is necessary because over time the insulation on a wire that is 
touching a rigid object, such as an equipment support bracket, will 
fail and expose bare wire. This can potentially lead to arcing that 
could destroy that wire and other wires in its bundle. Depending on the 
amount of electrical energy being carried by the failed wire, 
structural damage may also occur.
Section 25.1711 Component Identification: EWIS
    Proposed Sec.  25.1711 would require applicants to identify EWIS 
components using consistent methods that facilitate easy identification 
of the component, its function, and its design limitations. For EWIS 
associated with flight-essential functions, identification of the EWIS 
separation requirement would also be required.
    An important aspect of ensuring safe operation of airplanes is 
making sure that EWIS components are properly identified. This is 
necessary so that modification designers, maintenance personnel, and 
inspectors can easily determine the function of the associated system, 
together with any associated separation requirements and design 
limitations. Clear labeling of EWIS components and easy-to-understand 
identification aids allow installers, inspectors, and maintainers to 
readily ascertain that correct system components are installed as 
designed, and allow modifiers to add systems with due regard to the 
existing protection and separation requirements.
    The current part 25 certification requirement for equipment 
identification is Sec.  25.1301(b) and it is applicable to ``each item 
of installed equipment.'' This rule is inadequate for EWIS because it 
does not provide the specific requirements that have been determined 
necessary for identifying EWIS components. Specific EWIS component 
identification needs to be done to prevent modifiers from 
unintentionally introducing unsafe design or installation features on 
previously certified airplanes when they install new or modified 
systems. Component identification would also make those performing 
maintenance and inspections more aware of what systems are associated 
with specific EWIS in the areas undergoing maintenance or inspection.
    When the FAA first certifies an airplane type design, its systems 
are designed and installed to ensure safe operation of the airplane. 
Systems essential to that safe operation are often designed and 
installed to ensure redundancy of the system function. They have two or 
more circuits, or channels, that can perform the same function in case 
one of them malfunctions. Separate circuits (channels) typically have 
their own sensors, wiring, and equipment. This helps ensure that a 
common failure cannot cause failure of the entire system.
    An example of this is the autoland system on modern transport 
category airplanes. The autoland system allows airplanes to land during 
adverse weather conditions that would otherwise prevent landing with 
manual techniques that rely on the flightcrew's ability to see the 
runway. Typically the autoland system has three channels that are 
physically separated and electrically segregated, so if one channel 
fails, the airplane can safely continue the autoland procedure. The 
failure of an autoland system at a critical phase of flight can be 
catastrophic to the airplane and its passengers. The integrity of an 
autoland system's design could be compromised by systems installed 
after certification of the autoland system. One way to prevent this is 
to clearly identify EWIS associated with the autoland in a way that 
makes it easy to see that it is associated with a critical system. Such 
identification would aid the designers and installers of the new system 
by alerting them to the presence of the critical system and allow 
appropriate design and installation decisions, preventing degradation 
of the safety of the autoland system.
    The reverse is also true. For example, suppose an in-flight 
entertainment system is installed on an airplane and, after that 
installation, an autoland system is to be installed. The designers and 
installers of the autoland system would need to be able to identify 
EWIS associated with the IFE system so they do not mix IFE system EWIS 
with the autoland system EWIS. The IFE system is a passenger 
convenience item and its functionality is not important to the 
continued safe operation of the airplane. When the zone containing the 
autoland system EWIS is undergoing inspections or maintenance, easy 
identification of the EWIS will alert inspection or maintenance 
personnel to use extra caution in the area.
    Proposed Sec.  25.1711(a) uses language that is similar to existing 
Sec.  25.1301(b) but is specifically applicable to EWIS components. The 
proposal adds the word ``consistent'' to stress the need for 
consistency in EWIS identification to avoid confusion and mistakes 
during airplane manufacturing, modification, and maintenance. This 
means the FAA expects airplane manufacturers to develop an EWIS 
identification method that facilitates easy identification of the 
systems that any specific EWIS component supports and use that 
identification method in a consistent manner throughout the airplane. 
The consistent identification method must be used for new type 
certifications and changes to those designs. Proposed Sec.  25.1711(e) 
would require that modifications to type designs use EWIS 
identification methods that are consistent with the identification 
method of the original type design. The proposed requirements of 
paragraph (e) are discussed later in this document.
    Paragraph (b) would impose additional requirements for 
identification detail, when assessed in accordance with the proposed 
requirements of Sec.  25.1705, for EWIS components associated with:
     Systems required for safe flight and landing.
     Systems required for egress.
     Systems with potential to affect the flightcrew's ability 
to cope with adverse operating conditions.
    Paragraph (c) would require that identifying markings required by 
paragraphs (a) and (b) of the proposal remain legible throughout the 
design life of the component. As most wire installations are designed 
to remain on the airplane throughout the airplane's service life, this 
means the identification marks must be able to be read to support the 
intended purpose of the markings for the life of the airplane. The 
method of marking must take into account the environment in which the 
EWIS component will be installed.
    Paragraph (d) would require that the means used to identify an EWIS 
component does not have an adverse effect on the component's 
performance throughout its design life. Certain wire marking methods 
have the potential to damage the wire's insulation. Hot-stamp marking 
is one such method. According to SAE (Society of Automotive Engineers) 
aerospace information report

[[Page 58524]]

AIR5575, ``Hot Stamp Wire Marking Concerns for Aerospace Vehicle 
Applications,'' a copy of which is included in the docket, the hot-
stamp marking method is not well suited for today's generation of 
aircraft wiring. As noted in the SAE document, wire insulation has 
become markedly thinner over the years since the procedure was first 
introduced in the 1940s. Because of this, problems have arisen over 
wire damage from excessive penetration by the hot-stamp process. The 
document further states: ``The frequent need for adjustments in 
temperature, pressure, and swell time inherent to achieving legible hot 
stamp wire marking provides many opportunities for error. The controls, 
methods, and guidance necessary to achieve satisfactory performance 
with hot stamp marking are often not made available to operators in 
smaller wire shops.''
    The FAA concurs with this assessment. If damage to the insulation 
occurs during the marking process, it may fail later in service after 
it has been exposed to the sometimes-harsh environmental conditions of 
aircraft use. While the proposed regulation does not prohibit use of 
hot-stamp marking, its use is not encouraged. To comply with this 
paragraph, if the hot stamp marking process is used, the guidelines of 
SAE recommended practice ARP5369, ``Guidelines for Wire Identification 
Marking Using the Hot Stamp Process'' or equivalent must be followed. A 
copy of this document is in the docket.
    In some cases it may not be practicable to mark an EWIS component 
directly, because of component size or identification requirements. In 
this case other methods of identification such as a label or sleeve 
must be used.
    Paragraph (e) would require that EWIS modifications to the type 
design take into consideration the identification scheme of the 
original type design. This is to ensure that the consistency required 
by proposed Sec.  25.1711(a) is maintained when a modification is 
installed. The intent of this requirement is to provide continuity in 
the methods used for EWIS identification on a particular model. It is 
not the intent of the requirement to impose on the modifier the exact 
wire identification methods of the airplane manufacturer. However, 
since the purpose of proposed Sec.  25.1711 is to make it easy to 
identify those airplane systems essential to the safe operation of the 
airplane, it is in the best interest of safety that designers of any 
modifications to the original design consider the approved type design 
identification methods. For example it would not be appropriate for a 
modifier to use purple wire to identify a specific flight critical 
system when the approved type design used the color green, especially 
if the type design already uses purple wire to identify non-essential 
systems. Such a scheme could cause confusion and lead future modifiers 
or maintainers to believe that the routing of purple wires with green 
wires is acceptable. This is just an example and should not be 
construed to say that flight critical systems should use green wire or 
non-essential systems purple wire. The regulation does not prescribe a 
particular method for identification, but is meant to ensure that the 
consistency of the identification method required by paragraph (a) is 
maintained throughout the life of the airplane.
Section 25.1713 Fire Protection: EWIS
    Proposed Sec.  25.1713 would require that EWIS components meet the 
applicable fire and smoke protection requirements of Sec.  25.831(c). 
It would further require that EWIS located in designated fire zones be 
at least fire resistant. Insulation on electrical wires and cables 
would also be required to be self-extinguishing when tested in 
accordance with the applicable portions of Appendix F, Part I, of part 
25.
    During an emergency situation it is important that airplane systems 
needed by the flightcrew to effectively deal with the emergency be 
operative. To help ensure this, Sec.  25.869 requires that electrical 
systems components meet certain flammability requirements and be 
designed and installed to minimize probability of ignition of flammable 
fluids and vapors. Currently, Sec.  25.869(a) is applicable to wiring. 
The proposal is to move the requirements of Sec.  25.869(a) related to 
protection of wiring from fire and put them into the proposed Sec.  
25.1713. This will allow easy identification of the requirements for 
fire protection of EWIS, because they will be found in the proposed new 
subpart H, which is dedicated to EWIS regulations. Requirements of 
Sec.  25.869 dealing with isolation from flammable fluid lines have 
been moved to the new Sec.  25.1709 and requirements for allowance for 
deformation and stretching have been moved to Sec.  25.1703. As a 
result, we are amending Sec.  25.869 to accommodate this change.
Section 25.1717 Electrical Bonding and Protection Against Static 
Electricity: EWIS
    Proposed Sec.  25.1717(a) would require that EWIS used for 
electrical bonding and protection against static electricity meet the 
requirements of Sec.  25.899. Proposed Sec.  25.1717(b) would require 
that EWIS components used for any electrical bonding purposes (not just 
that used for protection against static electricity) provide an 
adequate electrical return path under both normal and fault conditions.
    The buildup and subsequent discharge of static electricity has the 
potential to create hazardous conditions for both airplane systems and 
people. Static electricity can injure people. It can also interfere 
with installed electrical/electronic equipment and cause ignition of 
flammable vapors. We are proposing to adopt Sec.  25.899 (as discussed 
in the section headed ``Electrical System Harmonization Rules'') to 
highlight the importance of considering electrical bonding and static 
electricity as a full aircraft requirement and to prevent hazardous 
effects of static electricity. The proper design and installation of 
EWIS components used to accomplish such protection is critical to 
ensure the hazardous effects of static discharge are minimized. For 
example, the cross-sectional area of bonding paths used for primary 
bonding paths is important in ensuring that a low electrical impedance 
is obtained, as is the method in which the bonding connection is made 
to the airplane structure. Thus, EWIS must be fully considered when 
designing and installing protection from the adverse effects of static 
electricity. The proposed Sec.  25.1717 highlights the importance EWIS 
has in providing this protection and requires that EWIS components meet 
the same requirements as other components used to show compliance with 
Sec.  25.899.
    The ARAC Electrical Systems Harmonization Working Group recommended 
the adoption of JAR 25.1353(e) as paragraph (e) of Sec.  25.1353. The 
JAR requires that electrical bonding provide an adequate electrical 
return path under both normal and fault conditions on airplanes with 
grounded electrical systems. ATSRAC recommended that the requirements 
of JAR 25.1353(e) be moved in their entirety to the proposed subpart H. 
We agree with that recommendation and, instead of adopting JAR 
25.1353(e) as Sec.  25.1353(e), we are proposing to adopt it as Sec.  
25.1717(b).
Section 25.1719 Systems and Functions: EWIS
    Proposed Sec.  25.1719 would require that EWIS components be 
considered in showing compliance with the certification requirements of 
specific airplane systems. Many of the current part 25 sections contain 
system specific requirements that apply to EWIS in an

[[Page 58525]]

indirect way. The EWIS associated with such systems play an integral 
role in ensuring the safe operation of the system and of the airplane. 
In general, the EWIS associated with any airplane system needs to be 
considered an integral part of that system and must be given the same 
design and installation attention as the rest of the system. The 
proposed Sec.  25.1719(a) contains this general requirement, while 
paragraph (b) of the proposal identifies specific sections of part 25 
that are associated with airplane systems where wire and its associated 
components play an important part in ensuring safety. These specific 
part 25 sections contain requirements that do not lend themselves to 
creating a separate EWIS-based Subpart H requirement.
    It is the intent of the proposed Sec.  25.1719 to require that EWIS 
be designed and installed to support systems required for type 
certification or by operating rules, including those systems addressed 
by the regulations specifically listed in paragraph (b) of the 
proposal. They must be considered part of those systems, and be given 
the same design and installation considerations as the rest of the 
system. While paragraphs (a) and (b) may seem redundant, we have listed 
specific sections in (b) to ensure that applicants are aware of the 
need to give EWIS associated with those systems the same consideration 
as the other components of those systems. We consider the general 
requirements of (a) necessary because there may be other regulations 
where EWIS must be considered in showing compliance with those 
regulations. It also ensures that EWIS is given full consideration for 
any system-related regulation adopted in the future.
Section 25.1721 Circuit Protective Devices: EWIS
    Proposed Sec.  25.1721 would require that electrical wires and 
cable be compatible with the circuit protective devices required by 
Sec.  25.1357.
    We recently adopted Sec.  25.1353(d)(1) based on recommendations of 
ARAC, as part of the effort to harmonize the requirements of JAA JAR 25 
and FAA 14 CFR part 25. Paragraph (d)(1) requires that electrical 
cables be compatible with the circuit protection devices required by 
Sec.  25.1357, so that a fire or smoke hazard cannot be created under 
temporary or continuous fault conditions. That requirement would be 
moved from Sec.  25.1353(d)(1) into the proposed Sec.  25.1721 in its 
entirety. The proposal also adds the word ``wire'' to the requirement. 
This is because this requirement applies to all sizes of wire, not just 
heavy-current-carrying cables.
Section 25.1723 Instruments Using a Power Supply: EWIS
    The proposed Sec.  25.1723 would require that EWIS components 
associated with flight and navigation instruments using a power supply 
be designed and installed so that compliance with Sec.  25.1331 is 
ensured.
    Section 25.1331 requires that flight and navigation instruments 
using a power supply must, in the event of the failure of one power 
source, be supplied by another power source. No change is proposed to 
the wording of that section.
Section 25.1725 Accessibility Provisions: EWIS
    The proposed new Sec.  25.1725 would require that means be provided 
to allow for inspection of EWIS and replacement of their components as 
necessary for continued airworthiness.
    Currently, Sec.  25.611 requires that means must be provided to 
allow inspection, replacement of parts, adjustment, and lubrication as 
necessary for principal structural elements and control systems. While 
wiring systems are not specifically referred to in the existing rule, 
the ``accessibility'' concept is easily applied to EWIS. Many of the 
wiring systems on airplanes today are very difficult to access and 
inspect. We now have an increased awareness of the importance of 
inspecting wiring for separation and for contamination and damage in 
order to ensure proper functioning, maintenance, and safety. We also 
know that when adjacent structures must be removed to allow access to 
wire installations, new possibilities for contamination, chafing, and 
other types of damage are introduced. Section 25.611 would be amended 
to specify that EWIS must meet the accessibility requirements of Sec.  
25.1725.
    The intent of proposed Sec.  25.1725 is to ensure that EWIS 
components be installed so that inspections, tests, repairs, and 
replacements can be undertaken, and that these can be carried out with 
a minimum of aircraft disassembly. This proposal would facilitate the 
proposed implementation of the new wiring inspection programs developed 
under proposed Sec.  25.1739 and the operating rules contained in this 
proposal.
Section 25.1727 Protection of EWIS
    Proposed Sec.  25.1727 would require that cargo or baggage 
compartments not contain any EWIS whose failure would adversely affect 
safe operation. It would also require that all EWIS be protected from 
damage by movement of people.
    Section 25.855(e) requires that no cargo or baggage compartments 
may contain any controls, wiring, lines, equipment, or accessories 
whose damage or failure would affect safe operation of the airplane 
unless they are protected so that they cannot be damaged by movement of 
cargo in the compartment and their breakage or failure will not create 
a fire hazard. The proposed regulations would remove the word 
``wiring'' from the current language and move those requirements, as 
they apply to EWIS, to the proposed Sec.  25.1727(a). Proposed Sec.  
25.855(j) would mandate that cargo or baggage compartment EWIS 
components must meet the requirements of Sec.  25.1727(a).
    The proposed Sec.  25.1727(b) and (c) are new EWIS requirements 
that currently don't exist in part 25. Paragraph (b) would require that 
EWIS be designed so that damage and risk of damage from movement of 
people in the airplane during all phases of flight, maintenance, and 
service, be minimized. Paragraph (c) would require designers to 
minimize damage and risk of damage to EWIS by items carried onto the 
airplane by passengers, cabin crew, and flightcrew. These two new 
requirements are justified by service experience that shows wires can 
easily be damaged by movement of people on the airplane and by items 
carried on board.
    Paragraph (b) would require that EWIS designers and installers 
consider such things as the routing of wires that could be damaged by 
personnel in the cargo compartments. For example, EWIS would have to be 
designed and installed in ways that prevent their use as hand-or 
footholds as much as practicable. It would further require that EWIS be 
protected from damage by people in the cabin or flight deck. More and 
more wiring is being routed to passenger seats to support increasingly 
complex passenger convenience features. If an airplane is equipped with 
seat-back monitors, for example, the electronic components necessary to 
support the monitor are typically mounted underneath the seat. This 
requires wire routing to the seats, usually through the seat tracks 
(structural channels used to fasten the seats to the floor) or from the 
side wall directly next to the seat. Many wires mounted on or under the 
seats have been damaged by passengers. In one case an airplane was 
operated with wires lying on the floor in the area where a passenger 
would put his feet. The wires had become dislodged from the seat track. 
This not only exposed the wires to damage but also posed a potential 
electrical shock risk to the passenger. In other cases, wires have been 
routed to the seats through holes cut into the cabin side wall, 
exposing them to damage from both passengers

[[Page 58526]]

and carry-on items stored beneath the seat or between the side wall and 
seat.
Section 25.1729 Flammable Fluid Fire Protection: EWIS
    The proposed Sec.  25.1729 would require that EWIS components be 
considered a potential ignition source in each area where flammable 
fluid or vapors might escape by leakage of a fluid system and must meet 
the requirements of Sec.  25.863.
    The current Sec.  25.863 mandates that, in each area where 
flammable fluids or vapors might escape by leakage of a fluid system, 
there must be means to minimize the probability of ignition, and 
resultant hazards if ignition does occur. Possible ignition sources, 
including overheating of equipment, malfunctioning of protective 
devices, and electrical faults must be considered in showing compliance 
with this rule. Many types of electrical faults could cause ignition. 
Among them are sparks emitting from an avionics component, overheated 
electrical component surfaces, and arcing from electrical wiring. The 
wording of Sec.  25.863 would not change.
Section 25.1731 Powerplants: EWIS
    The proposed Sec.  25.1731 specifies that EWIS associated with any 
powerplant must be designed and installed so that failure of an EWIS 
component will not prevent continued safe operation of the remaining 
powerplants or require immediate action by any crewmember for continued 
safe operation, in accordance with Sec.  25.903(b). It would also 
mandate that design precautions be taken to minimize hazards to the 
airplane because of EWIS damage in the event of a powerplant rotor 
failure or a fire originating in the powerplant that burns through the 
powerplant case, in accordance with Sec.  25.903(d)(1). The purpose of 
this section is to ensure proper consideration of EWIS in evaluating 
powerplant installation designs.
    The current Sec.  25.903(b) requires, among other things, that 
powerplants be arranged and isolated from each other to allow 
operation, in at least one configuration, so that failure or 
malfunction of any engine, or of any system that can affect the engine, 
will not prevent continued safe operation of the remaining engines or 
require immediate action by any crewmember for continued safe 
operation. Section 25.901(d)(1) requires that design precautions be 
taken to minimize hazards to the airplane in the event of an engine 
rotor failure or a fire originating within the engine that burns 
through the engine case.
Section 25.1733 Flammable Fluid Shutoff Means: EWIS
    Proposed Sec.  25.1733 would require that EWIS associated with each 
flammable fluid shutoff means and control be ``fireproof'' (as defined 
in Sec.  1.1) or located and protected so that any fire in a fire zone 
will not affect operation of the flammable fluid shutoff means, in 
accordance with Sec.  25.1189.
    Section 25.1189 requires that each engine installation and fire 
zone have a means to shut off or otherwise prevent hazardous quantities 
of fuel, oil, deicer, and other flammable fluids from flowing into or 
through any designated fire zone. No change is proposed for that 
section.
Section 25.1735 Fire Detector Systems, General: EWIS
    Proposed Sec.  25.1735 would require that EWIS associated with any 
installed fire protection system be considered in showing compliance 
with the applicable requirements for that particular system. This would 
be a new requirement. It does not currently exist in part 25. The 
current part 25 regulations contain fire detection system requirements 
for powerplants (Sec.  25.1203), lavatories (Sec.  25.854), and cargo 
compartments (Sec. Sec.  25.855, 25.857 and 25.858). Each fire 
detection system requires electrical wire. Failure of this wire could 
lead to inability of the detection system to function properly. The 
wire and other associated EWIS components must be considered an 
integral part of the fire detection system and meet the requirements of 
the applicable regulation. The proposal would apply to all required 
fire protection systems with the exception of powerplants and APUs. 
Requirements for EWIS associated with powerplant and APU fire detection 
systems are contained in proposed Sec.  25.1737.
Section 25.1737 Powerplant and APU Fire Detector System: EWIS
    Proposed Sec.  25.1737 would require that EWIS that are part of a 
fire or overheat detector system located in a fire zone be at least 
fire-resistant, as defined in Sec.  1.1. It would also require that 
EWIS components of any fire or overheat detector system for any fire 
zone may not pass through another fire zone unless:
     They are protected against the possibility of false 
warning caused by fire in the zone through which they pass, or
     Each zone involved is simultaneously protected by the same 
detector or extinguishing system.
    In addition, the proposal would require that EWIS that are part of 
a fire or overheat detector system in a fire zone meet the requirements 
of Sec.  25.1203.
    The current Sec.  25.1203 requires approved, quick acting fire or 
overheat detectors in each designated fire zone, and in the combustion, 
turbine, and tailpipe sections of turbine engine installations, to 
provide prompt indication of fire in those zones. The present rule does 
contain requirements for wire used in the fire detection systems. But 
to increase visibility of the related EWIS requirements and to gather 
them into one central place, a new rule devoted specifically to fire 
detector system EWIS is proposed.
    Existing Sec.  25.1203 would be amended to reference the new Sec.  
25.1737, thus effectively closing the loop on requirements.
Section 25.1739 Instructions for Continued Airworthiness: EWIS
    Proposed Sec.  25.1739 would require that applicants prepare EWIS 
ICA in accordance with the requirements of Appendix H to part 25. The 
proposed EWIS ICA requirements are discussed in the next section of 
this document.

B. Part 25 Subpart I--Continued Airworthiness and Related Part 25 
Changes

    As discussed below, the following proposals are applicable to 
holders of existing TCs for transport category airplanes and applicants 
for approval of design changes to those certificates. On July 12, 2005, 
we issued policy statement PS-ANM110-7-12-2005, ``Safety--A Shared 
Responsibility--New Direction for Addressing Airworthiness Issues for 
Transport Airplanes'' (70 FR 40166). The policy states, in part, 
``Based on our evaluation of more effective regulatory approaches for 
certain types of safety initiatives and the comments received from the 
Aging Airplane Program Update (July 30, 2004), the FAA has concluded 
that we need to adopt a regulatory approach recognizing the shared 
responsibility between design approval holders (DAH) and operators. 
When we decide that general rulemaking is needed to address an 
airworthiness issue, and believe the safety objective can only be fully 
achieved if the DAHs provide operators with the necessary information 
in a timely manner, we will propose requirements for the affected DAHs 
to provide that information by a certain date.''
    We believe that the safety objectives contained in this proposal 
can only be reliably achieved and acceptable to the FAA if the DAHs 
provide the operators with the EWIS- and fuel-tank-system-

[[Page 58527]]

related maintenance information required by the proposed operational 
rules for parts 91, 121, 125, and 129. Our determination that DAH 
requirements are necessary to support the initiatives contained in this 
proposal is based on several factors:
     Developing EWIS and fuel tank system ICA is complex. Only 
the airplane manufacturer, or DAH, has access to all the necessary type 
design data needed for the timely and efficient development of the 
required EWIS and fuel tank system maintenance tasks.
     FAA-approved EWIS and fuel tank system ICA need to be 
available in a timely manner. Due to the complexity of these ICA, we 
need to ensure that the DAHs submit them for approval on schedule. This 
will allow the FAA Oversight Office having approval authority to ensure 
that the ICA are acceptable, are available on time, and can be readily 
implemented by the affected operators. Additionally, accurate and 
timely information is necessary to ensure alignment with the 
requirements of the Fuel Tank Safety Rule (FTSR). The compliance 
deadline for the operational requirements of the FTSR was extended to 
facilitate this alignment, as stated in the Federal Register notice `` 
Fuel Tank Safety Compliance Extension (Final Rule) and Aging Airplane 
Program Update (Request for Comments)'' (69 FR 45936).
     The proposals in this NPRM affect a large number of 
different types of transport airplanes. Because the safety issues 
addressed by this proposal are common to many airplanes, we need to 
ensure that technical requirements are met consistently and the 
processes of compliance are consistent. This will ensure that the 
proposed safety enhancements are implemented in a standardized manner.
     The safety objectives of this proposal need to be 
maintained for the operational life of the airplane. We need to ensure 
that future design changes to the type design of the airplane do not 
degrade the safety enhancements achieved by the initial incorporation 
of EWIS and fuel tank system ICA. We need to be aware of future changes 
to the type designs to ensure that these changes do not invalidate the 
maintenance tasks assigned to a particular type design when the ICA are 
first developed under the requirements of this proposal.
    Based on the above reasons and the stated safety objectives of FAA 
policy PS-ANM110-7-12-2005, we are proposing to implement DAH 
requirements applicable to EWIS and fuel tank system ICA.
    In the past, we have issued a similar requirement in the form of a 
special federal aviation regulation (SFAR). But SFARs appear in various 
places in the CFR and are difficult to reference as a whole. The FAA 
believes that placing these types of requirements in a new subpart of 
part 25, which contains the airworthiness standards for transport 
category airplanes, would provide a single, readily accessible location 
for this type of requirement. Therefore, we are proposing new subpart I 
to part 25 to contain these requirements.
    In preliminary discussions with foreign airworthiness authorities 
of the concept of this new subpart, they have expressed concerns that 
their regulatory systems may not be able to accommodate these types of 
requirements in their counterparts to part 25. While agreeing on the 
need for these types of requirements, they have suggested that it may 
be more appropriate to place them in part 21 or another location. As 
discussed below, because we expect these new subpart I requirements to 
be similar to new part 25 airworthiness standards, we have tentatively 
decided to place them in part 25. However, we specifically request 
comments on the appropriate location of these requirements, 
particularly from the foreign authorities. If, based on comments 
received, we conclude that another location is more appropriate, we may 
move them in the final rule. Because such a move would not affect the 
substance of the requirements themselves, we would not consider this to 
be an expansion of the scope of this rulemaking that would require 
additional notice and comment procedures.
Section 25.1 Applicability
    As stated in Sec.  25.1, part 25 currently prescribes airworthiness 
standards for issuance of TCs, and changes to those certificates, for 
transport category airplanes. As discussed in more detail above, with 
this NPRM the FAA is proposing to expand the coverage of part 25 to 
include a new subpart I containing requirements that must be complied 
with by current holders of these certificates. Therefore, we are 
proposing to amend Sec.  25.1, ``Applicability,'' to state that part 25 
also includes requirements for holders of these design certificates. As 
discussed in the FAA's final rule, ``Fuel Tank Safety Compliance 
Extension and Aging Airplane Program Update'' (69 FR 45936), this NPRM 
is one of several proposals for adoption of these kinds of requirements 
for current holders of type certificates.
    A theme common to this and other possible subpart I proposed rules 
is that the rulemaking projects include proposals for changes to 
operational rules to require operators to implement programs or take 
other actions that the FAA has determined are necessary for safety. In 
several recent rules we have adopted operational requirements without a 
corresponding requirement for design approval holders to develop and 
provide the necessary data and documents to support the operators' 
compliance. The difficulty encountered by operators in complying with 
these rules has convinced us that the corresponding design approval 
holder requirements are necessary to enable operators to comply by the 
regulatory deadlines.
Section 25.2 Special Retroactive Requirements
    Section 25.2 currently contains ``special retroactive 
requirements.'' These requirements are ``retroactive'' in the sense 
that they require applicants for changes to TCs to comply with 
requirements that were not applicable to the original TC. As discussed 
below, proposed subpart I would have a similar effect, in that it would 
impose new requirements on both existing design certificate holders and 
applicants for changes to those certificates. Therefore, we are 
proposing to amend Sec.  25.2 to make reference to proposed subpart I.
Section 25.1801 Purpose and Definition
    Paragraph (a) of this section states that this subpart would 
establish requirements for holders of TCs to take actions necessary to 
address particular safety concerns or to support the continued 
airworthiness of transport category airplanes. Such actions may 
include, but are not limited to, performing assessments, making design 
changes, developing revisions to ICA, and making necessary 
documentation available to affected persons.
    The specific applicability of each subpart I rule will be 
established as part of the rulemaking adopting each rule. Generally 
this subpart would also apply to applicants for type certificates and 
changes that are pending as of the effective date of this rule. It 
would also apply to future applicants for changes to existing type 
certificates. Under Sec.  21.101, the FAA may determine that it is not 
appropriate to require such applicants to comply with new airworthiness 
standards, such as proposed new subpart H. However, it is appropriate 
for them to comply with the same requirements as existing certificate 
holders. Otherwise, the safety

[[Page 58528]]

improvements that result from type certificate holder compliance with 
these requirements could be undone by later modifications.
    For example, in the case of this proposed rule, as discussed below, 
operators would be required to revise their maintenance programs based 
on EWIS ICA developed by the type certificate holder. Unless future STC 
applicants are required to provide similar ICA for their modifications, 
the TC holder's ICA could become obsolete or, in some cases, even 
provide incorrect and potentially unsafe information as applied to the 
STC holder's modification. In other cases, because subpart I rules 
accompany corresponding operating requirements, failure of an STC 
applicant to comply with a subpart I rule could make it impossible for 
an operator to comply with the corresponding operating requirement. 
Subpart I does not apply to future applicants for TCs, because those 
applicants will be covered by other proposed changes to part 25, 
including Appendix H.
    Therefore, adoption of a new subpart I rule would also necessitate 
new requirements for certification of changes to TCs that are in 
addition to the requirements that are specified under Sec.  21.101. 
Under that section, if a change is ``significant'' and certain other 
criteria are met, the applicant would have to show compliance with the 
latest airworthiness requirements. For example, an applicant applying 
for such a change after this final rule becomes effective would have to 
comply with the proposed EWIS requirements in subpart H. Even if we 
determine that these broader regulations do not apply, the applicant 
for a change must still comply with the subpart I rule.
    Paragraph (b) of this section provides a definition of the term 
``FAA Oversight Office.'' The FAA Oversight Office is the aircraft 
certification office or office of the Transport Airplane Directorate 
with oversight responsibility for the relevant TC or STC, as determined 
by the Administrator. As stated later in the discussion of the proposed 
operating rules, the primary means for operators to comply with those 
requirements would be by implementing programs or taking other actions 
developed by the TC and STC holders under this proposed subpart. In 
each case, to ensure compliance with the relevant subpart I rule, the 
TC and STC holder's compliance documentation (for example, in this 
case, EWIS ICA) must be submitted to the FAA Oversight Office. Because 
we expect this will be a standard approach to compliance with the 
requirements of this subpart, we are including this definition in this 
section to avoid having to repeat it in each section within this 
subpart.
Section 25.1805 Electrical Wiring Interconnection Systems (EWIS) 
Maintenance Program
    This proposal would apply to holders of TCs and to applicants for 
new TCs, amended TCs, and supplemental TCs if the application was filed 
before the effective date of this rule and the certificate was issued 
on or after the effective date of this rule. It would also apply to 
future applicants for approval of changes to existing TCs.
    Paragraph (a) states that this rule would apply, with some 
exceptions, to transport category turbine-powered airplanes with a 
maximum type-certificated capacity of 30 or more passengers, or a 
maximum payload capacity of 7500 pounds or more resulting from the 
original certification of the airplane or later increase in capacity. 
This would result in the coverage of airplanes where the safety 
benefits and the public interest are the greatest.
    The reference to the originally certificated capacity, or later 
increase in capacity, is intended to address two situations:
     In the past, some designers and operators have tried to 
avoid applying requirements mandated only for airplanes over specified 
capacities by getting a design change approval for a slightly lower 
capacity. By referencing the capacity resulting from original 
certification, this proposal would remove this possible means of 
avoiding compliance.
     It is also possible that an airplane design could be 
originally certified with a capacity slightly lower than the minimum 
specified in this section, but through later design changes, the 
capacity could be increased above this minimum. The reference to later 
increases in capacity would ensure that, if this occurs, the design 
would have to meet the requirements of this section.
    Compliance is not proposed for airplanes with a certificated 
passenger capacity of fewer than 30 passengers, or having a maximum 
capacity of less than 7500 pounds payload resulting from original 
certification, because it is not clear at this time that the possible 
benefits for those airplanes would be proportionate to the cost 
involved. The FAA intends to evaluate the merits of applying these 
requirements to those airplanes. We are currently working with ATSRAC 
to assess how these issues might be addressed in those transport 
category airplanes. We request comments on the feasibility and benefits 
of requiring holders of TCs for those airplanes to comply with these 
requirements.
    This proposed rule, as it applies to EWIS, is not applicable to 
holders of existing (already issued) STCs. Often, the wire design for 
STC installations of EWIS was based on operator or repair station 
standard practices and therefore details of the installation are not 
available. In the cases where such information is available, it would 
usually indicate that the wiring for the modification follows the same 
path, or is in the same airplane zone, as the wiring in the original 
type design. We anticipate that operators would inspect those areas 
while performing the TC holder's EZAP program. We also expect that any 
possible discrepancies will be further mitigated by operators 
incorporating applicable EWIS maintenance tasks into the maintenance 
program for that zone. Accordingly, the FAA has decided not to require 
compliance with this section for existing STCs. However, if an existing 
STC is amended, this section would apply to the amendment.
    TC holders, who design EWIS on airplanes, are the technical experts 
who possess information about those systems. This proposal would apply 
to the following:
     TC holders.
     Applicants for TCs and for approval of design changes to 
existing TCs whose applications are pending when this rule becomes 
effective.
     Future applicants for approval of design changes to 
existing TCs.
    Section 25.1805(b) would require TC holders to complete a 
comprehensive assessment of the EWIS of each ``representative'' 
airplane for which they hold a TC, develop inspection and maintenance 
instructions for them, and incorporate those instructions into the 
airplane's ICA. The ``representative'' airplane is defined as the 
configuration of each model series airplane that incorporates all the 
variations of EWIS used on that model, and that includes all TC-holder-
designed modifications mandated by AD, as of the effective date of this 
rule.
    For example, for the Boeing Model 737, the representative airplane 
would be the configuration of each of the airplane series, 737-100 
through 737-900 that incorporates all the variations of EWIS used in 
producing each airplane series. The purpose of this definition is to 
ensure that the TC holder considers the full range of EWIS 
configurations that may affect the results of the EZAP. Further, AD 99-
03-04 applies to all Boeing Model 737-100, -200, -300, -400, and -500 
series

[[Page 58529]]

airplanes. It requires installation of components to provide shielding 
and separation of the fuel system wiring from adjacent wiring. It also 
requires installation of flame arrestors and pressure relief valves in 
the fuel vent system. Boeing would be required to develop ICA for each 
of those series airplanes as modified by installation of these 
components and all other modifications mandated by ADs.
    The purpose of including these mandated design changes is to ensure 
that the TC holder's EZAP addresses the existing configuration of 
airplanes in the operating fleet, rather than just the configuration 
produced and delivered by the manufacturer.
    Applicants for approval of design changes would be required to 
evaluate the effect of their proposed change on the EWIS ICA developed 
by the TC holder for the representative airplane and to develop EWIS 
ICA to address those effects. For TC holders, this requirement would 
apply to any design changes that may affect the ICA for the 
representative airplane. This includes service bulletins describing 
such design changes. Under Sec.  21.113, these design changes are 
amendments to the TC.
    A description of what must be included in those ICA, and the EZAP 
that must be used to develop them, is contained in the section of this 
preamble discussing the proposed revision to Appendix H, part 25.
    The requirement for ICA was effective on January 28, 1981. TC 
holders whose application was dated before that date are not subject to 
that requirement. This proposal would require TC holders who do not 
have ICA for specific airplane models to create EWIS ICA for them. As 
discussed below, air carriers and operators of those airplanes would 
then be required to revise their maintenance or inspection programs 
based on the new ICA for EWIS and fuel tank systems.
    As discussed earlier, SFAR 88 requires TC holders to develop 
maintenance and inspection instructions to assure the safety of the 
fuel tank system. Proposed Sec.  25.1805(b) would require that TC 
holders align the fuel tank system instructions with the results of the 
EZAP applied to EWIS to ensure compatibility and minimize redundancies. 
All EWIS would be subject to review in developing the EWIS ICA, and the 
appropriate instructions for their maintenance and inspection would be 
required. But some EWIS are also part of the fuel tank system. The 
requirements for their maintenance and inspection might be more 
specific than those for wiring in general, and might contain additional 
requirements. That is why the two must be reviewed for compatibility.
    As discussed later in this section, the ICA for fuel tank system 
electrical wiring required by SFAR 88 will be determined in accordance 
with guidance provided by Policy Statement ANM100-2004-1129, ``Process 
for Developing Instructions for Maintenance and Inspection of Fuel Tank 
Systems Required by SFAR 88'' (a copy of which may be found in the 
docket), or other acceptable process. Compliance with Subpart I will 
require ICA for the same wire to be determined using an EZAP. While 
these processes have similarities, they may result in identification of 
different tasks and intervals. The ICA maintenance tasks and intervals 
that result from these determinations are expected to be additive. If 
there is a conflict in the task or interval, for purposes of this 
section, the FAA Oversight Office will resolve the conflict.
    The ICA should be reviewed to ensure that any maintenance tasks for 
EWIS do not compromise fuel tank system wire requirements, such as 
separation or configuration specifications. If there is an inspection 
or maintenance requirement for EWIS and the fuel tank system within the 
same zone, there must be an effort to align the task interval. In 
addition, design certificate holder's existing documents containing 
EWIS and fuel tank system ICA should be reviewed to either remove or 
cross-reference redundant information.
    The compliance plan required by this proposal must include 
identification of those common locations in the airplane where EWIS and 
fuel tank ICA apply. The considerations for compatibility and 
minimization of redundancy for the two systems will be reviewed and 
approved by the FAA Oversight Office. The plan for documenting the 
required ICA for EWIS and fuel tank system will also be reviewed as 
part of the compliance plan. These documents are critical to the effort 
that will be required of operators to show compliance with the 
operational rules contained in this proposal. We intend that the ICA 
information, both in content and format, will be readily usable by the 
affected operators for developing proposed changes to their maintenance 
or inspection programs. Generally, the information contained in the ICA 
for the fuel tank system required by SFAR 88 would include:
     The location of the fuel tank system components to be 
maintained or inspected and any access requirements.
     Any unique procedures required, such as special, detailed 
inspections or dual sign-off of maintenance records.
     Specific task information, such as inspections defined by 
pictures or schematics.
     Intervals for any repetitive tasks.
     Methods, techniques, and practices required to perform the 
task.
     Criteria for passing inspections.
     Any special equipment or test apparatus required.
     Critical Design Configuration Control Limitations--for 
example, wire separation or pump impeller material specifications--that 
cannot be altered, except in accordance with the applicable limitation.
    The information for EWIS ICA would generally include:
     Identification of each zone of the airplane.
     Identification of each zone that contains EWIS.
     Identification of each zone containing EWIS that also 
contains combustible material.
     Identification of each zone in which EWIS is in close 
proximity to both primary and back-up hydraulic, mechanical, or 
electrical flight controls and lines.
     The location of the EWIS components to be maintained or 
inspected and any access requirements.
     Any unique procedures required, such as special, detailed 
inspections, or a dual sign-off of maintenance records.
     Specific task information, such as inspections defined by 
pictures or schematics.
     Intervals for any repetitive tasks.
     Methods, techniques and practices required to perform the 
task.
     Criteria for passing inspections.
     Any special equipment or test apparatus required.
     Instructions for protection and caution information that 
will minimize contamination and accidental damage to EWIS during 
performance of maintenance, alterations, or repairs.
     Guidelines for identifying wiring discrepancies and 
assessing what effect such discrepancies, if found, could have on 
adjacent systems, particularly if these include wiring.
     Critical Design Configuration Control Limitations--for 
example, wire separation specifications--that cannot be altered, except 
in accordance with the applicable limitation.
    Policy Statement No. PS-ANM100-2004-10029 provides guidance on 
acceptable processes for developing fuel tank system ICA as required by 
SFAR 88. The FAA expects that engineers from aircraft certification 
offices or from the Transport Airplane Directorate will review and 
approve the results of the EZAP.
    The three groups whose compliance with this proposal would be 
required,

[[Page 58530]]

and their required compliance dates, indicated in paragraph (c), are as 
follows:
     Existing TC holders: No later than December 16, 2007.
     Current applicants for TCs and amendments to TCs 
(including service bulletins describing design changes) whose 
applications are pending and future applicants for TC amendments: No 
later than December 16, 2007, or the date of approval of their 
application, whichever is later.
     Pending and future applicants for STCs: No later than June 
16, 2008, or the date of the approval of their application, whichever 
is later.
    Future applicants for changes to TCs that comply with proposed 
Sec.  25.1739 would not be required to comply with this section. As 
discussed previously, under Sec.  21.101, applicants for 
``significant'' changes that meet certain criteria must comply with the 
latest airworthiness requirements. If this NPRM is adopted as a final 
rule, such a future applicant would have to comply with Sec.  25.1739. 
Because the proposed requirements of that section are more extensive 
than the proposed requirements of Sec.  25.1805, requiring compliance 
with this section would be redundant.
    In determining the compliance schedules for the requirements 
covered in this proposal, the FAA balanced the safety-related reasons 
for the rule against the need to give industry enough time to comply 
with it. Therefore, before setting the proposed compliance times for 
the TC holders to complete their analysis of their representative type 
design, the FAA considered the following:
     Input from industry.
     Current or planned compliance periods of several aging-
related rulemakings, such as the pending Aging Airplane Safety proposed 
rule, Fuel Tank System safety initiatives (69 FR 45936, 66 FR 23086), 
and the pending Widespread Fatigue Damage proposal.
     Safety improvements that will result from compliance with 
this rule.
     Industry's current efforts to incorporate some of these 
safety initiatives.
    ATSRAC recommended a compliance time of 24 months for TC holders to 
develop these ICA. To align this proposal with other rules in the aging 
airplane program, the FAA has adjusted the time frame to that of other 
rules discussed earlier, so that operators can more efficiently comply 
with requirements to revise their maintenance programs. To support this 
realignment, compliance dates that allow an 18-month time frame for TC 
holders to develop the EWIS ICA and 12 months for operators to 
implement them were determined to be appropriate and were included in 
this proposal. We believe these time frames are supported by the 
experience gained from the EZAPs already performed. Since ATSRAC made 
its recommendation, several manufacturers have applied an EZAP to their 
type design airplanes and have completed those reviews.
    When we initially drafted this proposal, we assumed the final rule 
would be adopted by mid-2006. As a result, we set the compliance dates 
in the proposal using the mid-2006 time frame as the baseline. However, 
the proposed rulemaking process took longer than we had anticipated. 
Consequently, we expect that the time frame for adoption of the final 
rule will be sometime after mid-2006. We recognize that this delay will 
adversely impact the compliance dates we propose for TC holders and 
operators and we may need to adjust them. Therefore, we request and 
will consider your comments on revising the proposed compliance dates. 
Once the ICA are approved by the FAA Oversight Office, the submitter 
must make the ICA available to affected persons as required by Sec.  
21.50.
    Because this proposal sets a precedent in introducing part 25 
requirements for holders of existing TCs, it is the FAA's expectation 
that they will work closely with the FAA Oversight Office in putting 
together a compliance plan for developing the required ICA. Proposed 
section 25.1805(d) would require that the compliance plan be approved 
by the FAA Oversight Office as sufficient basis for showing compliance 
with the proposed Sec.  25.1805.
    The following table lists the FAA Oversight Offices, as currently 
determined by the Administrator, that oversee issuance of type 
certificates and amended type certificates for manufacturers of 
transport category airplanes with a passenger capacity of 30 passengers 
or a payload capacity of 7500 pounds or greater.

------------------------------------------------------------------------
         Airplane manufacturer                 FAA Oversight Office
------------------------------------------------------------------------
Aerospatiale...........................  Transport Airplane Directorate,
                                          International Branch, ANM-116.
Airbus.................................  Transport Airplane Directorate,
                                          International Branch, ANM-116.
BAE....................................  Transport Airplane Directorate,
                                          International Branch, ANM-116.
Boeing.................................  Seattle Aircraft Certification
                                          Office.
Bombardier.............................  New York Aircraft Certification
                                          Office.
CASA...................................  Transport Airplane Directorate,
                                          International Branch, ANM-116.
deHavilland............................  New York Aircraft Certification
                                          Office.
Dornier................................  Transport Airplane Directorate,
                                          International Branch, ANM-116.
Embraer................................  Transport Airplane Directorate,
                                          International Branch, ANM-116.
Fokker.................................  Transport Airplane Directorate,
                                          International Branch, ANM-116.
Lockheed...............................  Atlanta Aircraft Certification
                                          Office.
McDonnell-Douglas......................  Los Angeles Certification
                                          Office.
SAAB...................................  Transport Airplane Directorate,
                                          International Branch, ANM-116.
------------------------------------------------------------------------

    Development of a compliance plan is necessary to ensure that TC 
holders thoroughly understand the requirements of this proposal and 
produce on time appropriate ICA that are acceptable in content and 
format in addressing the maintenance and inspection tasks for EWIS and 
the fuel tank system. Integral to the compliance plan will be the 
inclusion of procedures to allow the FAA to monitor progress towards 
compliance. These aspects of the plan will help ensure that the 
expected outcomes will be acceptable and on time for incorporation by 
the affected operators in accordance with the operational rules 
contained in this proposal.
    To help ensure that TC holders are fully informed of what is 
necessary to show compliance with these requirements, as previously 
discussed, we are issuing AC 120.XX, and have issued a policy statement 
that describes an acceptable means, but not the only means, of 
complying with these requirements for developing EWIS ICA and the fuel 
tank system ICA required by SFAR 88. AC 120-XX, ``Program to Enhance 
Transport Category Airplane

[[Page 58531]]

Electrical Wiring Interconnection System Maintenance,'' provides an 
enhanced zonal analysis procedure (EZAP) for completing a review of the 
representative airplane covering all areas, including the flight deck 
(or cockpit), electrical power center, fuel tank wiring, and 
powerfeeder cables. Policy Statement ANM100-2004-10029, ``Process for 
Developing Instructions for Maintenance and Inspection of Fuel Tank 
Systems Required by SFAR 88,'' provides guidance for identifying ICA, 
including any airworthiness limitations, as a result of the fuel tank 
system review required by SFAR 88 and compliance with Amendment 102 to 
part 25 Appendix H and Sec.  25.981.
    Proposed Sec.  25.1805(d) is intended to provide TC holders, 
applicants with pending TC-amendment or STC applications, and the FAA 
with assurance that they understand what means of compliance are 
acceptable and have taken necessary actions, including assigning 
sufficient resources, to achieve compliance with this section. This 
paragraph is based substantially on ``The FAA and Industry Guide to 
Product Certification,'' which describes a process for developing 
project-specific certification plans for type certification programs. A 
copy of this guide may be found in the docket. This planning 
requirement would not apply to future applicants for TC amendments or 
STCs because, as described in the guide, this type of planning 
routinely occurs at the beginning of the certification process.
    The guide recognizes the importance of ongoing communication and 
cooperation between applicants and the FAA. Section 25.1805, while 
regulatory in nature, is intended to encourage establishment of the 
same type of relationship in the process of complying with this 
section. In particular, in addition to other necessary information, 
paragraph (d)(3) makes it clear that, to the extent that they intend to 
use means of compliance different from those already identified as 
acceptable by the FAA, it is imperative that they identify those 
differences at the earliest possible stage so any compliance issues can 
be resolved without risk of unnecessary expenditure of resources or, 
ultimately, noncompliance.
    Proposed Sec.  25.1805(d) would require TC holders and applicants 
to submit to the FAA Oversight Office the following within 90 days 
after the effective date of the rule:
     A proposed project schedule, identifying all major 
milestones, for meeting the compliance dates of this rule.
     A proposed means of compliance with this section, 
identifying all required deliverables, including all compliance items 
and all data to be developed to substantiate compliance. If any 
affected person has already initiated compliance, the FAA Oversight 
Office will review the results of those efforts to ensure that the 
results are acceptable.
     A detailed explanation of how the proposed means will be 
shown to comply with this section if the affected person proposes a 
means of compliance that differs from that described in FAA advisory 
material.
     A proposal for how the approved ICA will be made available 
to affected persons.
    It should be noted that this section applies not only to domestic 
TC holders and applicants, but also to foreign TC holders and 
applicants. In this sense, this section is different from most type 
certification programs, where foreign applicants typically work with 
their responsible certification authority, and the FAA relies on that 
authority's findings of compliance under bilateral airworthiness 
agreements. Since this rulemaking is not harmonized in all cases, the 
FAA will make all the necessary compliance determinations, and where 
appropriate we may accept findings of compliance made by the 
appropriate foreign authorities using procedures developed under the 
bilateral agreements. The compliance planning provisions of this 
section are equally important for domestic and foreign TC holders and 
applicants, and we will work with the foreign authorities to ensure 
that their TC holders and applicants perform the planning necessary to 
comply with the requirements of this section.
    One of the items required in the plan is, ``If the proposed means 
of compliance differs from that described in FAA advisory material, a 
detailed explanation of how the proposed means will comply with this 
section.'' FAA advisory material is never mandatory because it 
describes one means, but not the only means of compliance. In the area 
of type certification, applicants frequently propose acceptable 
alternatives to the means described in advisory circulars. But when an 
applicant chooses to comply by an alternative means, it is important to 
identify this as early as possible in the certification process to 
provide an opportunity to resolve any issues that may arise that could 
lead to delays in the certification schedule.
    The same is true for this requirement. As discussed earlier, TC 
holder compliance with this section on time is necessary to enable 
operators to comply with the operational requirements of this NPRM. 
Therefore, this item in the plan would enable the FAA Oversight Office 
to identify and resolve any issues that may arise with the TC holder's 
proposal without jeopardizing the TC holder's ability to comply with 
this section by the compliance time.
    As of the date of this proposal, certain TC holders have 
voluntarily started to develop the EWIS EZAP that would be required by 
proposed Sec.  25.1805. An EZAP has been completed on certain transport 
category airplanes. Although the EZAP used by those TC holders may not 
be the version outlined in AC120-XX, it is similar. The FAA would 
expect that after issuance of the final rule, these TC holders would 
either submit a plan proposing revisions to the EZAP for those model 
airplanes to be consistent with the guidance given in AC120-XX, or use 
the planning process to show that their EZAP complies with this 
section. The FAA Oversight Office will then review the results of those 
efforts to ensure that the results are acceptable for compliance with 
this section.
    Section 25.1805(e) requires that TC holders and applicants correct 
a deficient plan, or deficiencies in implementing the plan, in a manner 
identified by the FAA Oversight Office. Before the FAA formally 
notifies a TC holder or applicant of deficiencies, however, we will 
have communicated with them to try to achieve a complete mutual 
understanding of the deficiencies and means of correcting them. 
Therefore, the notification referred to in this paragraph should 
document the agreed corrections.
    Because operators' ability to comply with the applicable 
operational rules will be dependent on TC holders' and applicants' 
compliance with Sec.  25.1805, the FAA will carefully monitor their 
compliance and take appropriate action if they fail to achieve 
compliance. Failure to comply within the specified time would 
constitute a violation of the requirements and may subject the violator 
to certificate action to amend, suspend, or revoke the affected 
certificate in accordance with 49 U.S.C. Sec.  44709. In accordance 
with 49 U.S.C. 46301, it may also subject the violator to a civil 
penalty of not more than $25,000 per day per TC until Sec.  25.1805 is 
complied with.

C. Other Proposed Changes to Part 25

    As explained in the preamble discussion of the proposed subpart H, 
some existing rules applying to EWIS would need revision in order to 
support the proposed new subpart. Those rules that would be changed by 
this proposal are:
     25.611
     25.855

[[Page 58532]]

     25.869
     25.1203
     25.1301
     25.1309
     25.1353
     25.1357
    The changes proposed for them are discussed in the section-by-
section discussion for proposed subpart H. In addition, this NPRM 
includes a number of other changes to part 25 requirements for 
electrical systems discussed later in the section headed ``Electrical 
System Harmonization Rules.'' The remaining changes to part 25 are 
discussed below.
Section 25.1357(f) System Power Removal
    ATSRAC has proposed adding a requirement that airplane systems 
normally requiring power removal have a power switch to accomplish 
this, instead of relying on using the circuit breaker. The FAA has 
decided that this requirement belongs in Sec.  25.1357.
    It is not the intent of the proposal to require that every 
electrically powered system in the airplane have a means to remove 
power from them other than a circuit breaker. ATSRAC used the phrase 
``normally requiring power removal'' to distinguish between airplane 
systems normally turned on and off during normal operations, such as 
passenger convenience systems, and those systems normally powered at 
all times, such as the flightdeck multi-function displays or the flight 
management computer. But if, for example, the flight-management 
computer did require power cycling regularly, for whatever reason, this 
system would then be required to have a means to do this other than 
using the circuit breakers.
    For systems requiring this power removal design feature, power 
should be removed from the system as closely as practical to the source 
of power instead of simply deactivating the outputs of the systems 
power supplies.
    The ability to quickly remove power from an airplane system not 
required for the airplane's safe operation is important if an emergency 
situation demands isolation of a known or unknown source of fire or 
smoke. One of the first things flightcrews are instructed to do when 
faced with a fire or smoke emergency is to remove power from the known 
source or from all unnecessary systems if the source is unknown. This 
is to stop the fire or smoke from spreading. Currently, part 25 
regulations do not require systems to have a separate shutoff feature. 
But the need for the flightcrew to be able to shut off unnecessary 
systems was tragically illustrated during the investigation of the 
fatal accident on September 3, 1998, of a Swissair Model MD-11, 
discussed earlier in this document.
    After that accident, the FAA conducted a special certification 
review (SCR) on the IFE system installed on the airplane, and published 
its report (``Federal Aviation Administration Special Certification 
Review Team Report on: Santa Barbara Aerospace, STC ST00236LA-D, 
Swissair Model MD-11 Airplane, In-flight Entertainment System,'' June 
9, 2000. A copy of this report is contained in the docket). One of the 
team's findings was that the design of the IFE system did not allow the 
flightcrew or cabin crew to completely remove electrical power in any 
other way than by pulling the system's circuit breakers. The FAA 
decided that this was an unsafe condition, and we issued an 
airworthiness directive prohibiting operation of MD-11 airplanes with 
that particular IFE system installed. The FAA expanded its 
investigation and reviewed previously issued STCs that had approved 
installation of IFE systems on transport category airplanes. That 
investigation identified over 20 STC IFE installations that had the 
same design characteristics as the one on the accident MD-11 airplane 
(no means to remove power other than by pulling the circuit breaker). 
We issued ADs to correct those inadequate IFE system designs. As more 
IFE systems with the same design characteristic are identified, ADs 
will be issued to correct the identified unsafe condition.
    On September 18, 2000, the FAA issued a policy memorandum stating 
that a newly certified IFE system should have a way for the flightcrew 
or cabin crew to disconnect it from its source of power other than by 
using circuit breakers. A copy of this memorandum, titled ``Interim 
Policy Guidance for Certification of In-Flight Entertainment Systems on 
Title 14 CFR Part 25 Aircraft (Policy Number 00-111-160),'' is in the 
docket. Most airplane manufacturers are now equipping IFE systems on 
their newly delivered airplanes with a power source disconnection 
means. Subsequent policy covering cabin video surveillance systems also 
contains the same guidance (Policy Number 01-111-196, ``Interim Summary 
of Policy and Advisory Material Available for Use in the Certification 
of Cabin Mounted Video Cameras Systems with Flight Deck Displays on 
Title 14 CFR Part 25 Aircraft,'' included in the docket). ATSRAC (as 
recommended by the ATSRAC Wire Systems Harmonization Working Group and 
the ARAC Electrical Systems Harmonization Working Group) believes that 
this philosophy should be applied to any airplane system that requires 
having its power removed or reset during normal operations. The FAA 
agrees with this recommendation.
    The proposed Sec.  25.1357(f) would require that airplane systems 
needing a capability for having their power removed or reset during 
normal operations must be designed so that circuit breakers are not the 
primary means to do that. This is a new regulation whose requirements 
have not previously existed within part 25 and is a recognition that 
any airplane system, including an IFE system, that requires regular 
power removal or resetting needs to have a means to do so.
Appendix H to Part 25--Instructions for Continued Airworthiness
    As previously noted, improper maintenance, repair, and 
modifications often hasten the ``aging'' of EWIS. To properly maintain, 
repair, and modify airplane EWIS, certain information must be available 
to the designer, modifier, and installer. This information should be 
part of the ICA as required by current Sec.  25.1529 and the proposed 
Sec.  25.1739.
    This proposal would amend Appendix H by adding a new section, 
H25.5, to require TC applicants to develop maintenance information for 
EWIS as part of the ICA as a requirement for getting a design approval. 
The proposed rule would also apply to applicants for design change 
approvals (supplemental TCs and amended TCs).
    The proposal would require applicants for TCs to prepare ICA for 
EWIS that are approved by the FAA Oversight Office, in the form of a 
document that is easily recognizable as an EWIS ICA. To prepare these 
instructions, they must use an EZAP such as the one described in AC120-
XX, ``Program to Enhance Aircraft Electrical Wiring Interconnection 
System Maintenance'' to perform a review of their representative 
airplane covering all areas, including the flightdeck (also known as 
the cockpit), electrical power center, fuel tank wiring and powerfeeder 
cables, as well as the engine. Applicants for design change approvals 
would have to perform a similar review for their proposed design 
changes.
    A zonal analysis procedure is an assessment of the structures and 
systems within each physical zone of the airplane. It is used to 
develop an inspection program to assess the general condition and 
security of attachment of all system components and structures items 
contained in the zone, using general visual inspections (GVI). An 
enhanced zonal analysis procedure

[[Page 58533]]

(EZAP) is an enhanced version of the zonal analysis procedure. It 
focuses on EWIS components. An EZAP-generated inspection program might 
call for the use of stand-alone GVI and detailed inspections (DET). A 
stand-alone GVI is one that is performed separately from the regularly 
scheduled GVI (typically more frequently) and is focused on a 
particular area or component. In this case, the focus would be wiring. 
So while the zonal analysis procedure would result in a regularly 
scheduled GVI for the entire zone, in which each of its systems and 
structures are inspected at the same time, the EZAP could result in 
additional GVIs or DETs for the EWIS in that zone, which occur more 
frequently. These inspection techniques are discussed later in this 
section.
    An EZAP identifies the physical and environmental conditions 
contained in each zone of an airplane, analyzes their effects on 
electrical wiring, and assesses the possibilities for smoke and fire. 
From such an analysis, maintenance tasks can be developed to prevent 
ignition sources and to minimize the possibilities for combustion by 
minimizing the accumulation of combustible materials. Such a procedure 
would involve dividing the airplane into physical areas, or zones, 
including actual physical boundaries such as wing spars, bulkheads, and 
cabin floor, and access provisions for the zone, and identifying which 
of those zones contain EWIS components. For those zones with EWIS 
components, characteristics and components of all systems installed in 
the zone would be listed. The EWIS in the zone would be described, 
including information on the full range of power levels carried in the 
zone. And the presence or possibilities for ignition sources or 
accumulation of combustibles would be noted.
    Combustibles are any materials that could cause a fire to be 
sustained in the event of an ignition source. Examples of combustible 
materials would be dust or lint accumulation, contaminated insulation 
blankets, and fuel or other combustible liquids or vapors. Wire 
contaminants are foreign materials that are likely to cause degradation 
of wiring. Wire contaminants can also be combustibles. Some commonly 
used airplane liquids, like engine oils, hydraulic fluids, and 
corrosion prevention compounds, might be readily combustible, but only 
in vapor or mist form. In that case, an assessment must be made of 
conditions that could exist within the zone that would convert the 
liquid to that form. Combustibles appearing as a result of any single 
failure must be considered. An example would be leaks from connection 
sites of unshrouded pipes. For the purposes of this new requirement, 
the term combustible does not refer to material that will burn when 
subjected to a continuous source of heat as occurs when a fire 
develops. Combustibles, as used here, will sustain a fire without a 
continuous ignition source.
    An EZAP must address:
     Ventilation conditions in the zone and the density of the 
installations that would affect the presence and build-up of 
combustibles and the possibilities for combustion. Avionics and 
instruments located in the flightdeck and equipment bays, which 
generate heat and have relatively tightly packed installations, require 
cooling air flow. The air blown into the area for that cooling tends to 
deposit dust and lint on the equipment and EWIS components.
     Liquid contamination on wiring. Most synthetic oils and 
hydraulic fluids, while they might not be combustibles by themselves, 
could be an aggravating factor for accumulation of dust or lint. This 
accumulation could then present fuel for fire. Moisture on wiring may 
increase the probability of arcing from small breaches in the 
insulation, which could cause a fire. Moisture on wires that contain 
insulation breaches can also lead to ``arc tracking.'' As discussed 
previously, arc tracking is a phenomenon in which an electrical arc 
forms a conductive carbon path across an insulating surface. The carbon 
path then provides a short circuit path through which current can flow. 
Short circuit current flow from arc tracking can lead to loss of 
multiple airplane systems, structural damage, and fire.
     EWIS in close proximity to both primary and back-up 
hydraulic, mechanical, or electrical flight controls.
     The type of wiring discrepancies that must be addressed if 
they are identified by general visual or detailed inspections. A 
listing of typical wiring discrepancies that should be detectable 
during EZAP-derived EWIS inspections is given in AC120-XXX, Section B 
``Guidance for Zonal Inspections.''
     Proper cleaning methods for EWIS components.
    Once information about such contaminants and combustibles within an 
airplane zone is collected, each identified possibility for combustion 
would then be addressed to determine whether a specific task could be 
performed to reduce that possibility. An example of a specific task to 
reduce build-up of combustibles on EWIS components is the use of 
temporary protective covers (such as plastic sheeting) over EWIS 
components in a zone where corrosion prevention fluids are being used. 
This would minimize the amount of fluid contamination of the EWIS 
components. Preventing fluid contamination reduces the probability of 
other contaminants, like dust and dirt, accumulating on the EWIS 
components. If no task can be developed to prevent accumulation of 
combustibles in a zone, such as the dust blown through the air by 
cooler fans, then tasks must be developed to minimize their buildup, 
such as scheduled cleaning.
    Developing an ICA to define such tasks would include assessing 
whether particular methods of cleaning would actually damage the EWIS 
components. Although regular cleaning to prevent potential combustible 
build-up would be the most obvious task for an EWIS ICA, other 
procedures might also be called for. A detailed inspection of a 
hydraulic pipe might be appropriate, for instance, if high-pressure 
mist from a pinhole caused by corrosion could accumulate on a wire 
bundle in a low ventilation area, creating a possibility for electrical 
arcing.
    Proximity of EWIS to both primary and back-up hydraulic, 
mechanical, or electrical flight controls within a zone would affect 
the criticality of inspections needed, their level of detail, and their 
frequency. Even in the absence of combustible material, wire arcing 
could adversely affect continued safe flight and landing if hydraulic 
pipes, mechanical cables, or wiring for fly-by-wire controls are routed 
close to other wiring.
    The EZAP-generated ICA must be produced in the form of a single 
document, easily recognizable as EWIS ICA for that specific airplane 
model. The single document is relevant to the maintenance and 
inspection aspects of the ICA, and not the standard wiring practices 
manual or electrical load analysis, etc.
    The ICA must define applicable and effective tasks, and the 
intervals for performing them, to:
     Minimize accumulation of combustible materials.
     Detect wire contaminants.
     Detect wiring discrepancies that may not otherwise be 
reliably detected by inspections contained in existing maintenance 
programs.
    As noted earlier, among the types of tasks to be developed from an 
EZAP are general visual inspections (GVI) and detailed inspections 
(DET). A GVI is defined as a visual examination of an interior or 
exterior area, installation, or assembly to detect obvious damage, 
failure, or irregularity. This level of inspection is made from within 
touching distance of the inspected

[[Page 58534]]

object unless otherwise specified. It is made under normally available 
lighting conditions such as daylight, hangar lighting, flashlight, or 
droplight and may require removal or opening of access panels or doors. 
It may be necessary to use a mirror to improve visual access to all 
exposed surfaces in the inspection area. Stands, ladders, or platforms 
may be required to gain proximity to the area being checked. It is 
expected that the area to be inspected is clean enough to minimize the 
possibility that accumulated dirt, grease, or other contaminants might 
hide unsatisfactory conditions that would otherwise be obvious. It is 
also expected, as an outcome of the EZAP applied to EWIS, that any 
cleaning considered necessary would be performed in accordance with 
procedures that minimize the possibility of the cleaning process itself 
introducing anomalies. The EZAP must identify guidelines to assist 
personnel performing a GVI in identifying wiring discrepancies and in 
assessing what effect such discrepancies, if found, could have on 
adjacent systems, particularly if these include wiring. As discussed 
previously, a list of typical wiring discrepancies that should be 
addressed is contained in proposed AC120-XX, Section B, ``Guidance for 
Zonal Inspections.''
    A DET is an intensive examination of a specific item, installation, 
or assembly to detect damage, failure, or irregularity. Available 
lighting is normally supplemented with a direct source of good lighting 
at an intensity considered appropriate. Inspection aids, such as 
mirrors, magnifying lenses, or other means, may be necessary. Surface 
cleaning and elaborate access procedures may be required. A DET can be 
more than just a visual inspection. It may include tactile assessment 
to check a component or assembly for tightness and security. Such an 
inspection may be needed to ensure the continued integrity of 
installations such as bonding jumpers, terminal connectors, etc.
    A DET would be required when the developer of the EZAP determines 
that a GVI is inadequate to reliably detect anomalies or degradation of 
EWIS components. Any detected discrepancies must be corrected according 
to the operator's approved maintenance procedures. It is not intended 
that the EZAP ICA identify how to correct detected discrepancies.
    To prevent improper modification and repair of existing EWIS or the 
improper installation of a new EWIS, modification designers and 
modification personnel must know the applicable standard wiring 
practices, EWIS identification requirements, and electrical load data 
for the airplane undergoing modification. The proposed Appendix H 25.5 
would also require that the following information be included in ICA 
applicable to EWIS:
     Standard wiring practices data.
     Wire separation design guidelines.
     Information to explain the airplane's EWIS identification 
method required by the proposed Sec.  25.1711.
     Electrical load data and instructions for updating that 
data. Such information will help ensure that those modifying, 
repairing, or installing new EWIS will not perform any action that will 
adversely affect previously certified systems and unintentionally 
introduce potential hazards.
    Standard wiring practices are defined as standards developed by the 
specific airplane manufacturer or industry-wide standards for the 
repair and maintenance of EWIS. They include procedures and practices 
for the installation, repair, and removal of EWIS components, including 
information about wire splices, methods of bundle attachment, 
connectors and electrical terminal connections, bonding, and grounding. 
Although a standard wiring practices manual is not a design manual, and 
those designing a new EWIS modification for a specific model airplane 
should not use it as such, it does provide the designer with insight 
into the types of EWIS components used by the TC holder and the 
procedures recommended by the manufacturer for maintenance or repair 
that supports continued airworthiness of the components.
    EWIS separation guidelines are important for maintaining the safe 
operation of the airplane. Maintenance and repair personnel need to be 
aware of the type certificate holders' separation requirements so they 
do not compromise separation in previously certified systems. In fuel 
tank systems, the separation of certain wires may be critical design 
configuration control items and therefore qualify as an airworthiness 
limitation. Maintenance personnel need to be aware of these guidelines 
and limitations because many times wire bundles must be moved or 
removed to perform necessary maintenance. They must be able to readily 
identify EWIS associated with systems essential to the safe operation 
of the airplane.
    Similarly, those who design and install new EWIS need to be aware 
of separation requirements so they can use the same methods to develop 
the required separation for the EWIS they are adding to the airplane. 
This would help to ensure both that newly added EWIS is adequately 
separated from other EWIS, airplane system components, and structure so 
they do not damage the added EWIS, and that the addition of the new 
EWIS does not invalidate separation for previously certified EWIS.
    Electrical load data and the instructions for updating that data 
are necessary to help ensure that future modifications or additions of 
equipment that consume electrical power do not exceed the generating 
capacity of the onboard electrical generation and distribution system. 
The existing Sec.  25.1351(a)(1) mandates that the required generating 
capacity, and the number and kinds of power sources, must be determined 
by an electrical load analysis. Typically, after an airplane is 
delivered and enters service, it is modified numerous times throughout 
its service life. Each addition or deletion of an electrical-power-
consuming system changes the electrical load requirements. The only way 
to ensure that the capacity of the overall generating and distribution 
system, as well as individual electrical buses, is not exceeded is to 
have an up-to-date electrical load analysis. The best way to ensure 
that an up-to-date electrical load analysis is maintained is for the 
type certificate holder to include such data in the ICA provided with 
the airplane when it is first delivered to a customer, along with 
recommended practices for keeping it updated as electrical loads are 
deleted and added.

D. Part 25 Electrical System Harmonization Rules

    At the time the EWIS certification requirements contained in this 
proposal were being developed, several existing part 25 certification 
requirements were also undergoing revision under a separate joint 
harmonization effort with the European JAA. The FAA had tasked ARAC to 
develop recommendations for harmonized rules (64 FR 66522). The intent 
of that harmonization effort was to develop a common set of standards 
between 14 CFR part 25 and JAR-25. As mentioned previously, JAR-25 is 
the European counterpart to part 25.
    When ATSRAC began developing the EWIS requirements proposed in this 
NPRM, the process of developing harmonized proposals was essentially 
complete, although NPRMs had not yet been published in the Federal 
Register. So ATSRAC worked on the assumption that the harmonized rules 
would be in effect by the time this proposal was published, and used 
the new proposed harmonized part 25 as the baseline for the proposed 
EWIS requirements. This NPRM revises several of the harmonized

[[Page 58535]]

rules to accommodate the proposed new EWIS requirements.
    Three of those harmonized part 25 proposals, Sec.  25.869(a), Sec.  
25.1353(a), (c)(5), (c)(6), (d), and Sec.  25.1431(d), have already 
been adopted as final rules (69 FR 12526). We're revising the new 
25.1353(a) in this NPRM. Some of the remaining harmonized rules have 
been published as NPRMs. But several others have not. Therefore, to 
ensure consistency in the proposed EWIS requirements, those harmonized 
requirements on which ATSRAC recommendations are based, and which have 
not yet been published as final rules, are included in this NPRM. These 
are: Sec. Sec.  25.899, 25.1309, 25.1310, 25.1357, 25.1360, 25.1362, 
and 25.1365.
    The following discusses the proposed harmonization rules that must 
be adopted to support the addition of the proposed part 25 EWIS 
certification requirements. We believe the public should be aware of 
the background and full reasoning behind each change to these 
standards.
Section 25.899 Electrical Bonding and Protection Against Static 
Electricity
    Proposed Sec.  25.899 would contain requirements for electrical 
bonding and protection against static electricity. Current Sec. Sec.  
25.581, 25.954, and 25.1316 contain requirements for protecting the 
airplane and its systems from the effects of lightning strikes. But the 
current requirements do not address the hazards that could occur 
because of the accumulation of electrostatic charge. Static electricity 
can cause electrical shock hazards to people, ignite fuel vapors, and 
cause electromagnetic interference of airplane systems. Proposed Sec.  
25.899 would require that electrical bonding and protection against 
static electricity be designed to minimize accumulation of 
electrostatic charge that could cause human injury from electric shock, 
ignition of flammable vapors, or interference with electrical and 
electronic equipment. Compliance could be shown by bonding the 
components properly to the airframe or by incorporating other 
acceptable means to dissipate static charge.
    This proposal would adopt a modified version of the current 
proposed JAR 25X899. As currently written, the JAR duplicates some of 
the lightning protection requirements of JARs 25.581, 25.985, and 
25.1316. That proposed JAR 25X899 will be revised as well, and those 
duplications removed, for the purposes of this harmonization.
    There is currently no Sec.  25.899. This new requirement is 
necessary to ensure electrical bonding and static protection is fully 
addressed as a design standard. Proposed Sec.  25.899 maintains the 
same level of safety as currently exists because it reflects and 
codifies current industry practices. The proposed change would affect 
airplane manufacturers by requiring compliance with the new sections of 
the regulations. However, this would have a minimal effect in practice 
because airframe manufacturers must comply with proposed standards when 
seeking joint FAA-JAA certification of their products, so there would 
be little change required from the standards they have been using to 
comply with the existing proposed JAR 25X899.
    The FAA has developed advisory material about the requirements for 
bonding and static electricity protection in transport category 
airplanes. This material is contained in proposed AC 25.899-1.
Section 25.1309 Equipment, Systems, and Installations and Section 
25.1310 Power Source Capacity and Distribution.
    Proposed new Sec.  25.1310 is composed of material now covered in 
Sec.  25.1309(e) and (f). The current standards define an ``essential 
load'' on the power supply and the conditions under which those loads 
must be supplied. An ``essential load'' is each equipment installation 
whose function is required for type certification or by operating rules 
and that requires a power supply. These paragraphs require that power 
sources must be able to supply those loads under a number of specified 
failure conditions. These requirements are not directly related to the 
safety and analysis requirements of Sec.  25.1309. For that reason, and 
to make them more accessible, we propose to move them to a new section 
where they would stand alone. There is no current Sec.  25.1310.
    The goal of harmonization was to ``envelope'' to the more stringent 
requirements, which in this case are those contained in the current 
Sec.  25.1309(e) and (f). The proposal is to adopt as Sec.  25.1310 the 
more stringent current Sec.  25.1309(e) and (f). The JAA has agreed to 
adopt the same requirements in a new JAR 25.1310 (JAR NPA25df-317). 
Current Sec.  25.1309(g) would be redesignated as Sec.  25.1309(e). The 
proposed new Sec.  25.1310 and JAR 25.1310 would not be completely 
harmonized because JAR 25.1310 contains requirements for maintenance of 
airworthiness essential services after failure of any two engines on a 
three-engined airplane and makes reference to two JAR Advisory Circular 
Joint materials (ACJ). But the proposed standard maintains the same 
level of safety as the current regulations. It is in line with current 
design practices and will have a minimum effect on the airplane 
operators and manufacturers.
    There is no current published FAA advisory material for the 
proposed rule. ARAC has recommended that the JAR ACJ to 25.1310(a) be 
adopted as FAA advisory material because it provides a useful, 
acceptable means of compliance. The FAA plans to adopt it.
Section 25.1357 Circuit Protective Devices
    Section 25.1357 specifies standards for use, functional 
requirements, and installation requirements for electrical circuit 
protective devices. These standards protect the airplane's wiring from 
electrical faults or malfunctions.
    JAR paragraph 25.1357(d) contains a requirement to provide 
sufficient spare fuses, formerly located in paragraph (f). The reason 
the JAA moved this text from paragraph (f) to (d) was to make it clear 
that the spare fuse requirement does not apply to fuses that are 
inaccessible in flight. We propose to revise Sec.  25.1357 to move the 
spare fuse requirement of paragraph (f) to paragraph (d) to harmonize 
with the JAR requirement.
    The proposed standard continues to address the underlying safety 
issue by providing protection for the airplane's electrical system from 
wiring faults or malfunctions, and by ensuring that there is no 
confusion about use of spare fuses in flight. It would maintain the 
same level of safety relative to the current regulations and is in line 
with current industry practice.
    Manufacturers and operators of transport category airplanes could 
be affected by the proposed change. But since it is in line with 
current industry practice and does not result in any practical changes 
in requirements or practice, such effects would not be significant.
    The JAR paragraph 25.1357(a) references advisory material, ACJ 
25.1357(a), which states that the effects of variations in ambient 
temperatures on either the protective device or the equipment it 
protects must not result in hazards. We intend to revise our current AC 
25-1357 to include this ACJ material. The announcement of a new AC on 
the effects of temperature variations will be published in the Federal 
Register once it is available to the public. Comments on the proposed 
AC will be invited in that notice.
Section 25.1360 Precautions Against Injury
    Also to harmonize with the standards of JAR, the FAA proposes to 
add a new section, Sec.  25.1360, concerning electric

[[Page 58536]]

shock and burn protection. Currently, there is no part 25 requirement 
for precautions against injury from electrical shock and burns. Adding 
the JAR requirement to part 25 would increase safety. The proposed JAR 
25X1360, with its related ACJ material, would require that the 
electrical system and equipment must be designed to minimize risk of 
electrical shock and burns to the crew, passengers, and maintenance and 
servicing personnel during normal operations. The ACJ provides advisory 
material for high voltages and high temperatures and a means of 
compliance to the requirements.
    The proposed action is to harmonize the regulations by the adoption 
of JAR 25X1360 and its ACJ material in its entirety. The proposed 
standard is more stringent for part 25 because it adds a new 
requirement and new advisory material. But it is in line with current 
industry practice, and therefore would maintain the level of safety.
    The FAA intends to publish advisory material that adopts the 
existing JAA advisory material.
Section 25.1362 Electrical Supplies for Emergency Conditions.
    The FAA proposes to add a new section, Sec.  25.1362, about 
electrical supplies for emergency conditions. There is no part 25 
standard addressing electrical supplies for emergency conditions 
equivalent to JAR 25.1362. Partial coverage is provided by Sec. Sec.  
25.1189, 25.1195, 25.1309, and 25.1585.
    The JAR 25.1362 and associated ACJ material were created to ensure 
that electrical supplies for emergency functions (such as fuel and 
hydraulic shut-off valves) are maintained so they are operable after 
the flight crew has switched off the main power sources. This is 
necessary so emergency procedures can be performed. Since there is no 
equivalent standard to JAR 25.1362 in part 25, but partial coverage is 
provided by Sec. Sec.  25.1189, 25.1195, 25.1309, and 25.1585, 
application of JAA standards by U.S. manufacturers and aircraft 
operators has sometimes resulted in different designs for the powering 
of appropriate emergency functions.
    The proposed action would adopt a new Sec.  25.1362 harmonized to a 
revised JAR 25.1362. The new harmonized standard would provide for a 
consistent application of the standards. The ACJ would be revised and 
adopted as a new AC by the FAA. This proposed rule and advisory 
material would provide flexibility by allowing either an appropriate 
airplane flight manual (AFM) procedure or design implementation to 
achieve compliance with the standards.
    This proposal addresses the underlying safety issue by ensuring 
that appropriate electrical power supplies are maintained to emergency 
services after the main power sources have been switched off by the 
flightcrew. The proposal increases the level of safety by focusing on 
appropriate methods to ensure that electrical power is provided for 
emergency functions during emergency landing or ditching conditions. It 
is in line with current industry practice. Another option considered 
was to adopt the existing JAR and ACJ into 14 CFR. But revising the JAR 
and the ACJ material and creating a new Sec.  25.1362 and AC 25-1362 
results in a harmonized standard that would provide greater flexibility 
for compliance.
    Since this proposed change is in line with current design 
practices, the effect is considered to be minimal for aircraft 
operators and manufacturers affected by this change.
    There is no FAA advisory material available. This proposal would 
create a new AC 25-1362 harmonized with ACJ 25X1362.
Section 25.1365 Electrical Appliances, Motors, and Transformers
    The FAA proposes to add a new section, Sec.  25.1365, within the 
``Miscellaneous Equipment'' section of subpart F, concerning design and 
installation of domestic appliances. The term ``domestic appliance'' is 
used to refer to those items placed on the airplane to provide service 
amenities to passengers. Examples of domestic appliances are cooktops, 
ovens, microwave ovens, coffee makers, water heaters, refrigerators, 
and toilet flush systems. In turn, domestic systems are those such as 
lavatories or galleys, that may contain one or more domestic 
appliances. IFE equipment, however, is not considered equipment that 
falls under the definition of a domestic appliance. Proposed Sec.  
25.1365 is now covered by Sec.  25.1309(b), which does not specifically 
address electrical appliance motors and transformers.
    The proposed Sec.  25.1365 would require that domestic appliances 
be designed and installed so that in the event of failures, the 
requirements of Sec. Sec.  25.1309(b), (c), and (d) would be satisfied. 
It would further require that galleys and cooking appliances be such as 
to minimize risk of overheating or fire and that they be installed to 
prevent damage or contamination of other equipment from fluids or 
vapors resulting from spillage during use of the appliances. It would 
also require that electric motors and transformers be provided with a 
thermal protection device unless it can be shown that the circuit 
protective device required by Sec.  25.1357(a) would be sufficient to 
show compliance with the requirements of Sec.  25.1309(b).
    Adoption of the proposal would address concerns that faulty galley 
heating equipment (ovens) often cause smoke or fire in the cabin, and 
that circuit protection devices used in motor power supplies for those 
appliances have not always provided enough protection against failures.
    The proposed standard would be an improvement over current safety 
practices because current part 25 does not specifically address 
electrical appliance motors and transformers. The FAA considers that a 
new Sec.  25.1365 specifically addressing domestic appliances is the 
most appropriate way to increase the level of safety. The JAA is 
adopting the same requirement as JAR 25.1365.
    Aircraft operators and manufacturers, together with suppliers of 
galley and electrical equipment, could be affected by this change. 
Since newly certificated aircraft may have to be supplied with newly 
designed galley equipment, airplane operators may elect to introduce 
the same new equipment into their existing fleet to maintain fleet 
commonality.
    A new AC 25-1365 will be developed and an announcement of its 
availability for comment will be published in the Federal Register.

E. Proposed Changes to Part 91, 121, 125, and 129 Operating Rules for 
Fuel Tank Systems and EWIS and Other Existing Continued-Airworthiness-
Related Rules

    As discussed earlier, the proposed alignment of the ICA 
requirements for EWIS and the fuel tank system is a result of an FAA 
review and realignment of the Aging Airplane Program. We have 
determined that certain compliance dates in the existing rules and 
pending proposals could be better aligned. Other changes to the rules 
and proposals are necessary to increase the cost-effectiveness of these 
rules and proposals. Therefore, we have decided to revise those 
requirements and proposals and to align the compliance schedules as 
nearly as possible. This effort also includes a proposal to create new 
subparts in parts 25 (subpart I, discussed earlier), 91, 121, 125, and 
129. These new subparts would contain certain rules in this proposal 
and other existing and future rules that pertain to the support of

[[Page 58537]]

continued airworthiness, in particular, rules addressing aging airplane 
issues. The FAA believes that inclusion of certain rules under the new 
subparts will improve the reader's ability to readily identify rules 
pertinent to continued airworthiness.
    The table below illustrates what proposed and existing requirements 
will be included in these new subparts. Each of these new subparts is 
titled ``Continued Airworthiness.'' The proposed new subparts consist 
of relocated, revised, and new regulations pertaining to continued 
airworthiness of the airplane. Unless we say otherwise, our purpose in 
moving requirements to these new subparts is to ensure easy visibility 
of those requirements applicable to the continued airworthiness of the 
airplane. We do not intend to change their legal effect in any other 
way.

                    New Continued Airworthiness Subparts for Parts 25, 91, 121, 125, and 129
----------------------------------------------------------------------------------------------------------------
                                     Part 91 new/        Part 121 new/       Part 125 new/       Part 129 new/
   Part 25 new/relocated rules      relocated rules     relocated rules     relocated rules     relocated rules
   within proposed  Subpart I       within proposed     within proposed     within proposed     within proposed
                                       Subpart L           Subpart Y           Subpart M           Subpart B
----------------------------------------------------------------------------------------------------------------
Sec.   25.1801--Purpose and       Sec.   91.1501--    Sec.   121.901--    Sec.   125.501--    (Proposed Subpart
 definition (new).                 Purpose and         Purpose and         Purpose and         A would contain a
                                   definition (new).   definition (new).   definition (new).   revised Sec.
                                                                                               129.1 and all of
                                                                                               existing part 129
                                                                                               except Sec.  Sec.
                                                                                                 129.16, 129.32,
                                                                                               and 129.33).
Sec.   25.1803--Reserved........  Sec.   91.1503--    Sec.   121.903--    Sec.   125.503--    Sec.   129.101--
                                   Reserved.           Reserved.           Reserved.           Purpose and
                                                                                               definition (new).
Sec.   25.1805--Electrical        Sec.   91.1505--    Sec.   121.905--    Sec.   125.505--    Sec.   129.103--
 wiring interconnection systems    Repairs             Aging airplane      Repairs             Reserved.
 (EWIS) maintenance program        assessment for      inspections and     assessment for
 (new).                            pressurized         records reviews     pressurized
                                   fuselages           (formerly Sec.      fuselages
                                   (formerly Sec.      121.368).           (formerly Sec.
                                   91.410(a)).                             125.248(a)).
                                  Sec.   91.1507--    Sec.   121.907--    Sec.   125.507--    Sec.   129.105--
                                   Fuel tank system    Repairs             Fuel tank system    Aging airplane
                                   maintenance         assessment for      inspection          inspections and
                                   program (new)       pressurized         program (new)       records reviews
                                   (replaces           fuselages           (replaces           for U.S.-
                                   requirements of     (formerly Sec.      requirements of     registered
                                   Sec.   91.410(b)).  121.370(a)).        Sec.                multiengine
                                                                           125.248(b)).        aircraft
                                                                                               (formerly Sec.
                                                                                               129.33).
                                                      Sec.   121.909--    ..................  Sec.   129.107--
                                                       Supplemental                            Repairs
                                                       inspections                             assessment for
                                                       (formerly Sec.                          pressurized
                                                       121.370a).                              fuselages
                                                                                               (formerly Sec.
                                                                                               129.32(a)).
                                                      Sec.   121.911--    ..................  Sec.   129.109--
                                                       Electrical wiring                       Supplemental
                                                       interconnection                         inspections for
                                                       systems (EWIS)                          U.S.-registered
                                                       maintenance                             aircraft
                                                       program (new).                          (formerly Sec.
                                                                                               129.16).
                                                      Sec.   121.913--    ..................  Sec.   129.111--
                                                       Fuel tank system                        Electrical wiring
                                                       maintenance                             interconnection
                                                       program (new)                           systems (EWIS)
                                                       (replaces                               maintenance
                                                       requirements of                         program (new).
                                                       Sec.
                                                       121.370(b)).
                                                                                              Sec.   129.113--
                                                                                               Fuel tank system
                                                                                               maintenance
                                                                                               program (new)
                                                                                               (replaces
                                                                                               requirements of
                                                                                               Sec.
                                                                                               129.32(b)).
----------------------------------------------------------------------------------------------------------------

    As previously stated, other future rules pertaining to the support 
of continued airworthiness would also be contained in these proposed 
new subparts. Several such proposals are currently under development. 
But because of uncertainties in the timing of adoption of final rules, 
it is not always possible to estimate which of the proposals currently 
being developed will reach final rule stage first. In order to ensure 
that the proposed new subparts for continued airworthiness have been 
established in 14 CFR to contain whichever of several new continuing 
airworthiness proposals is adopted, the FAA has decided to use a 
``building block'' strategy to establish the new subparts.
    Until the new subparts have been established in 14 CFR as part of a 
final rule, each of several proposals containing new continued 
airworthiness rules will include language needed to set up the proposed 
subparts. Once one of those proposals becomes final, and the new 
continued airworthiness subparts are thus established, then other 
continued-airworthiness-related proposals will delete any language 
relating to setting up the new subparts. They will retain only the rule 
language pertinent to that specific proposal.
    A result of this ``building block'' strategy of proposed rulemaking 
is the possibility that two or more NPRMs may appear in the Federal 
Register proposing the same new continued airworthiness subparts for 14 
CFR at the same time. The language setting up the operational rule 
subparts will be the same in each rulemaking. But the language setting 
up subpart I of part 25 will vary slightly because of differences in 
the applicability of each rule. The proposed applicability in proposed 
Sec. Sec.  25.1 and 25.1801 will be correct for each NPRM. Otherwise, 
commenters addressing each NPRM might be confused by an inconsistency 
between the applicability of the subpart and the applicability of the 
individual proposed rule sections. And until final decisions are made 
on the content of each later NPRM, it would be inappropriate and 
potentially misleading for this NPRM to propose that content.
    If this NPRM, which has the narrowest applicability of several

[[Page 58538]]

proposals in development, is adopted first, then as each of the other 
final rules is adopted, Sec. Sec.  25.1 and 25.1801 would be amended to 
expand the applicability to cover what's added in the new rule. For 
instance, one proposal might cover holders of existing supplemental 
type certificates (STCs), so Sec.  25.1 and Sec.  25.1801, as adopted 
in this NPRM, would be amended to reference those holders. If a 
proposal applying to them is adopted first, then when this proposal is 
adopted, we can remove the proposed Sec.  25.1 and Sec.  25.1801 from 
the final rule, because those provisions would already be included in 
the previously adopted rule.
    When all the proposals currently under development are issued as 
final rules, Sec.  25.1 and Sec.  25.1801 will be as broad as they need 
to be to cover all of the rules. If any of those rules currently under 
development is not issued, then those sections would be only as broad 
as is needed for the rules that are adopted. Because the language in 
each NPRM will have been appropriate for that specific NPRM, the public 
will have been given adequate notice for all of the provisions in the 
final versions of those sections.
    Paragraph (a) of the ``Purpose and definition'' sections of part 
91, subpart L, part 121, subpart Y, part 125, subpart M, and part 129, 
subpart B generally describes the applicability of these subparts and 
states that the purpose of the various sections in these subparts is to 
prescribe requirements to support continued airworthiness. While most 
of the requirements of these subparts would address the need for 
improved maintenance, these subparts may also include requirements to 
modify airplanes or take other actions that we consider necessary for 
continued airworthiness.
    Historically, the only means used by the FAA to impose these types 
of requirements was the AD process. Under part 39, ADs address unsafe 
conditions that we determine are likely to exist or develop on other 
products of the same type design. In recent years, the FAA has 
identified a number of fleet-wide continued airworthiness issues, 
particularly relating to aging airplanes, that are not limited to 
particular type designs. Under these circumstances, general rulemaking 
may be a more efficient and appropriate way to address these types of 
problems than ADs. These new subparts provide locations for these types 
of requirements.
    Paragraph (b) of these sections provides a definition of the term 
``FAA Oversight Office.'' As stated in the discussion of proposed Sec.  
25.1801, the FAA Oversight Office is the aircraft certification office 
or office of the Transport Airplane Directorate with oversight 
responsibility for the relevant type certificate or supplemental type 
certificate, as determined by the Administrator. As discussed 
previously, the primary means for operators to comply with the 
requirements of these subparts would be by implementing programs or 
taking other actions developed by the TC and STC holders under proposed 
subpart I of part 25. In each case, to ensure compliance with the 
relevant subpart I rule, the TC and STC holder deliverables must be 
approved by the FAA Oversight Office. Because we expect this will be a 
standard approach to compliance with the requirements of these 
subparts, we are including this definition in these sections to avoid 
having to repeat it in each section within these subparts.
Proposed Changes to Parts 121 (Subpart Y) and 129 (Subpart B)--EWIS 
Maintenance Programs
    Paragraph (a) states that these sections would apply to transport 
category, turbine powered airplanes with a maximum type certificated 
passenger capacity of 30 or more, or having a maximum payload capacity 
of 7500 pounds or more resulting from the original certification of the 
airplane or later increase in capacity. This applicability provision 
coincides with that of proposed Sec.  25.1805 and is intended to ensure 
that, if a TC or STC holder is required to develop EWIS ICA for an 
airplane design, the operator of that airplane is required to implement 
them. As discussed previously, certain vintage airplanes would be 
excluded from these requirements. This applicability would result in 
the coverage of airplanes where the safety benefits and the public 
interest are the greatest. This action would affect approximately 7,000 
U.S. registered airplanes in parts 121 and 129 operations.
    Paragraph (b) of these sections would add requirements for 
maintenance programs for EWIS for part 121 certificate holders and part 
129 foreign air carriers and foreign operators of U.S. registered 
aircraft. Paragraph (c) would require them to develop a maintenance 
program for EWIS based on ICA for EWIS prepared by TC or STC holders. 
As discussed previously, the changes to part 25 would require both 
holders of existing TCs and future applicants for TCs and design 
changes to provide affected operators with these ICA.
    The compliance date for adopting these maintenance program changes 
is December 16, 2008. Assuming this proposal is adopted by mid-2006, 
this proposal would give operators 30 months after the effective date 
of the final rule to make these changes. Because the proposed 
compliance date in Sec.  25.1805 for holders of existing TCs is 
December 16, 2007, operators would have one year after that date to 
comply with this section.
    For pending and future design changes approved after December 16, 
2008, operators incorporating such a change would have to revise their 
maintenance program to incorporate EWIS ICA before returning the 
airplane to service.
    Paragraph (d) would require that operators keep their EWIS 
maintenance programs current as they modify their airplanes. As 
discussed earlier, the proposed changes to part 25 would ensure that, 
for modifications affecting EWIS, the applicant for the design approval 
will provide necessary revisions to the ICA. This paragraph would 
ensure that operators installing those modifications on their airplanes 
would revise their maintenance program to incorporate these ICA 
revisions.
    Paragraph (e) would require that the maintenance program changes 
required by these sections be approved by the operator's principal 
inspector. We are in the process of developing guidance for principal 
inspectors to ensure that their reviews are consistent and focused on 
the key implementation issues.
    Assuming this proposal is adopted by mid-2006, this proposal would 
give the affected air carriers and operators 30 months after the 
effective date of the final rule to incorporate those ICA for EWIS into 
their manuals. Thereafter, inspections and maintenance of EWIS and fuel 
tank systems must be carried out at the intervals specified in the 
operator's maintenance program.
    Many problems caused by inadequate wire maintenance practices have 
been discussed previously in this document. Much effort has been 
devoted to identifying the maintenance practices that could either 
prevent such incidents and accidents from occurring again or mitigate 
their causes. The purpose of this new section is to ensure that 
enhanced EWIS and fuel tank system maintenance techniques are put into 
practice on a continuing basis in airplane maintenance programs. Proper 
use of existing methods, techniques, and practices, combined with 
knowledge gained through ATSRAC activities, service history, research, 
and analysis, will result in improved wire system safety.

[[Page 58539]]

Proposed Changes to Parts 91 (Subpart L), 121 (Subpart Y), 125 (Subpart 
M), and 129 (Subpart B)--Fuel Tank Maintenance Programs
    These proposals would require part 91 and part 125 operators, part 
121 certificate holders, and part 129 foreign air carriers and foreign 
persons operating U.S. registered airplanes to incorporate fuel tank 
system ICA into their inspection or maintenance programs. As discussed 
earlier, one of the main objectives of this rulemaking is to align the 
operational requirements for fuel tank maintenance programs with the 
proposed requirements for EWIS maintenance programs. To that end, 
except as discussed below, the current fuel tank requirements would be 
revised to be parallel with the EWIS operational requirements discussed 
earlier. We provide the justification for these parallel provisions in 
the earlier discussion of the EWIS proposal, and it is not repeated 
here.
    Part 91 and part 125 operators are required to have an inspection 
program. Part 121 air carriers are required to have an inspection 
program and a program covering maintenance, preventive maintenance, and 
alterations for their airplanes. As provided by Sec.  43.13(a), 
operators may choose to follow the maintenance instructions developed 
by the TC holder or they may develop their own maintenance 
instructions, as long as they are acceptable to the Administrator. But 
they must comply with the airworthiness limitations section of the ICA. 
Foreign persons or foreign air carriers operating a U.S. registered 
aircraft are required to have a maintenance program approved by the 
Administrator.
    Because of the Fuel Tank Safety Rule, the above-listed operators 
and air carriers must now incorporate instructions for inspection and 
maintenance of the fuel tank system into their inspection or 
maintenance programs. These instructions must address the actual 
configuration of the fuel tank systems and they must be approved by the 
FAA aircraft certification office (ACO) having cognizance over the TC 
for the affected airplane. The compliance time for incorporation of the 
fuel tank system instructions for inspection and maintenance into the 
inspection or maintenance programs was changed on July 30, 2004 to 
December 16, 2008. The reasons for that change were briefly outlined 
earlier in this document in the discussions about rule alignment. This 
proposal would change the current requirements for the instructions for 
fuel tank inspections and maintenance that must be incorporated into 
operators' and air carriers' inspection or maintenance programs in the 
following ways:
     The FAA Oversight Office must approve ICA for the fuel 
tank system, and the operator's principal inspector or Flight Standards 
District Office (FSDO) must approve the operator's program changes 
incorporating those ICA.
    The current rule requires the ACO to approve individual operator 
fuel tank maintenance programs. The FAA recognizes that, as long as the 
ICA are approved by the ACO, ACO approval of the operators' maintenance 
program changes incorporating those ICA imposes unnecessary burdens on 
both the operators and the ACOs. With this proposed change, principal 
inspectors or the cognizant FSDO would be responsible for reviewing and 
approving program changes to address fuel tank safety. But, as stated, 
the ICA on which the operator's program is based must be approved by 
the FAA Oversight Office.
     The instructions for fuel tank maintenance and inspection 
developed by the TC holders will be referenced as the ``fuel tank 
ICA.'' The previous rule language referred to ``instructions for 
maintenance and inspection of the fuel tank system,'' even though it 
was widely understood throughout the industry that these instructions 
would be contained in the ICA. Because these requirements are now being 
aligned with the proposed requirements for EWIS to facilitate operator 
compliance, and the EWIS requirements refer to ICA as the place where 
EWIS maintenance instructions may be found, the FAA believes that using 
a consistent term to refer to the required information in both rules 
would clarify the common intent of the requirements and make them 
easier for operators to understand.
     The fuel tank ICA must address the fuel tank system as 
defined by the airplane's TC, any supplemental TCs, and any field 
approved incorporated auxiliary fuel tank systems. The current 
requirements mandate that the ICA must be developed for the ``actual 
configuration of the fuel tank systems of each affected airplane.'' 
That wording, however, proved to be unclear to many in the industry. 
The changed language is proposed to clarify the original intent.
    To further clarify what STCs should be included, the FAA has 
created a list by airplane model of STCs affected by this proposed 
rule. That list has been placed in the docket for this rulemaking and 
may also be viewed at http://qps.airweb.faa.gov/QuickPlace/sfar88ops/Main.nsf.
    The holders of those STCs, as well as the TC holders for the 
affected airplane models, must develop the ICA as required by SFAR 88. 
We are also proposing to make it clear that the operator is required to 
develop the maintenance instructions for field-approved auxiliary fuel 
tanks. Because there is no other design approval holder for these 
tanks, there is no other person in a better position to develop these 
instructions. As with the original requirements of the Fuel Tank Safety 
Rule, we expect that operators who do not have the expertise to develop 
these instructions will be able to contract with experts to help them.
    The proposed operational rules also make it clear that they apply 
to ICA developed under SFAR 88, to ICA developed for new or amended 
certificates under Sec.  25.1529 Amendment 102, and to any later 
revisions to those ICA. These proposed operational rules would require 
that operators revise their maintenance and inspection programs to 
incorporate ICA changes associated with alterations affecting the fuel 
tank ICA. This is necessary because an alteration may invalidate 
existing fuel tank system ICA, and compromise the safety objectives of 
the proposed rules.

H. Advisory Circulars

    As indicated in the discussion of ATSRAC recommendations that 
appeared earlier in this document, the advisory committee has produced 
four guidance documents as products of the working group activities 
that have contributed to this proposed rule. Those guidance documents 
are on maintenance, training, and standard wiring practices manuals, as 
well as on the proposed new subpart H. We have used these documents as 
the basis for developing the accompanying advisory circulars. Notices 
of availability for comment for the training, standard wiring 
practices, and subpart H ACs are published elsewhere in the Federal 
Register. Notice of availability for the maintenance AC will be 
published as soon as possible.
    Advisory materials for the design approval holder (DAH) 
requirements of subpart I and for the part 25 electrical system 
harmonization rules are also made available in notices of availability 
for comment published elsewhere in the Federal Register.
    In addition, guidance material entitled ``Process for Developing 
Instructions for Maintenance and Inspection of Fuel Tank Systems 
Required by SFAR 88'' was made available as a policy statement on May 
28, 2004 at http://www.airweb.faa.gov/rgl. Comments have been received 
and are being reviewed. Advisory Circular 25.981-1B, ``Fuel Tank 
Ignition Source

[[Page 58540]]

Prevention Guidelines,'' gives guidance on showing compliance to 
certification requirements for prevention of ignition sources within 
the fuel tanks of transport category airplanes. It also gives guidance 
on developing ICA for fuel tank systems. It can be found in the docket 
for this NPRM.

VI. Regulatory Analyses and Notices

Authority for This Rulemaking

    The FAA's authority to issue rules regarding aviation safety is 
found in Title 49 of the United States Code. Subtitle I, section 106 
describes the authority of the FAA Administrator. Subtitle VII, 
Aviation Programs, describes in more detail the scope of the agency's 
authority. This rulemaking is promulgated under the authority described 
in subtitle VII, part A, subpart III, section 44701, ``General 
requirements.'' Under that section, the FAA is charged with promoting 
safe flight of civil aircraft in air commerce by prescribing--
     Minimum standards required in the interest of safety for 
the design and performance of aircraft;
     Regulations and minimum standards in the interest of 
safety for inspecting, servicing, and overhauling aircraft; and
     Regulations for other practices, methods, and procedures 
the Administrator finds necessary for safety in air commerce.
    This regulation is within the scope of that authority because it 
prescribes--
     New safety standards for the design of transport category 
airplanes, and
     New requirements that are necessary for safety for the 
design, production, operation, and maintenance of those airplanes, and 
for other practices, methods and procedures relating to those 
airplanes.

Paperwork Reduction Act

    This proposal contains the following new information collection 
requirements. As required by the Paperwork Reduction Act of 1995 (44 
U.S.C. 3507(d)), the Department of Transportation has submitted the 
information requirements associated with this proposal to the Office of 
Management and Budget for its review.
    Title: Enhanced Airworthiness Program for Airplane Systems/Fuel 
Tank Safety (EAPAS/FTS).
    Summary: This proposal consists of regulatory changes applying to 
wiring systems and fuel tank systems in transport category airplanes. 
Some of those changes would require new information collection. The 
proposed new information requirements and the persons who would be 
required to provide that information are described below.

Required Information, Use, and Respondents

    (1) Proposed Sec.  25.1711 would require that electrical wiring 
interconnection systems (EWIS) components be labeled to identify the 
component, its function, and its design limitations, if any. If the 
EWIS is part of a system that requires redundancy, the labeling would 
also include component part number, function, and separation 
requirements for bundles. This specificity of labeling would be 
required to ensure that maintenance can be handled properly and with 
the appropriate caution for maintaining the safety features the wiring 
system was designed to provide. The information marked on the wires 
would be used by maintenance personnel for repair and cautionary tasks, 
and by modifiers so that original safety features are retained during 
modifications. The future airplane manufacturer and anyone who modifies 
the airplane would bear the burden of this labeling requirement.
    (2) Proposed Sec.  25.1805 would require that existing TC holders 
develop Instructions for Continued Airworthiness (ICA) for EWIS. 
Applicants for approval of design changes would be required to develop 
revisions to those EWIS ICA for any modifications to the airplane that 
might affect them. Proposed Sec.  25.1739 and Appendix H would apply 
the requirement for EWIS ICA to future applicants for TCs. EWIS ICA 
would be used by operators to prepare their maintenance programs. This 
requirement would be necessary to ensure that wiring is properly 
maintained and inspected to avoid problems that could affect safety.
    (3) Proposed subpart I would also require that TC holders submit to 
the FAA a plan detailing how they intend to comply with its 
requirements. This information would be used by the FAA to assist the 
TC holder in complying with requirements. The compliance plan would be 
necessary to ensure that TC holders fully understand the requirements, 
correct any deficiencies in planning in a timely manner, and are able 
to provide the information needed by the operators for the operators' 
timely compliance with the rule.
    (4) Anyone operating an airplane under part 121 would be required 
to revise their existing maintenance program to incorporate the 
maintenance and inspection tasks for EWIS contained in the EWIS ICA 
required by subpart I. The information incorporated into the 
maintenance program would be used by maintenance personnel to maintain 
the integrity of airplane wiring systems. This requirement would be 
necessary to ensure that wiring is properly maintained and inspected to 
avoid problems that could affect safety.
    (5) As a result of the revised maintenance programs that would be 
required for airplanes operating under part 121, maintenance personnel 
will be performing inspections and maintenance procedures to address 
safety issues specific to wiring systems. Although this NPRM does not 
specifically require new training, existing Sec.  121.375 requires that 
certificate holders or persons performing maintenance have a training 
program to ensure that persons determining the adequacy of such work 
(including inspectors) are fully informed about the procedures and 
techniques involved and are competent to perform them. To comply with 
this requirement in relation to proposals for revised maintenance 
programs for EWIS included in this NPRM, certificate holders would be 
required to develop any additional training program needed to ensure 
that the appropriate personnel are adequately prepared to carry out the 
revised maintenance programs.
    (6) The proposed revision to part 25 Appendix H would require that 
future manufacturers include acceptable EWIS practices in their ICA, 
presented in a standard format. This information would be used by 
maintenance personnel for wiring maintenance and repairs. The 
requirement is necessary because information about cautionary tasks 
during maintenance that can prevent situations that could compromise 
safety need to be available to maintenance personnel. Standard wiring 
practices manuals, in which this information is presented, often differ 
from manufacturer to manufacturer and so are difficult for maintenance 
personnel to find specific information in. The requirement for a 
standard format is meant to correct this. Because of this proposal, 
manufacturers would change their Standard Wiring Practices Manuals 
(SWPM).

Annual Burden Estimate

    To provide estimates for the burden associated with this NPRM, the 
FAA developed categories corresponding to information collection 
impacts of requirements contained in the proposal. The summary table 
below contains the impacted entities, average annual hours and hardware 
costs, and the corresponding average annual cost. Details of the 
estimates are in the paragraphs below.

[[Page 58541]]



----------------------------------------------------------------------------------------------------------------
                                      Proposed                                        Average         Average
       Entities impacted            requirement             Hardware cost          annual hours     annual cost
----------------------------------------------------------------------------------------------------------------
Airplane Manufacturers.........  Wire               ............................          12,046        $430,524
                                  identification
                                  (30 seconds per
                                  label).
Airplane Manufacturers.........  Label............  5 cents per label...........  ..............          72,275
Airplane Modifiers.............  Wire               ............................          18,417         658,224
                                  identification
                                  (30 seconds per
                                  label).
Airplane Modifiers.............  Label............  5 cents per label...........  ..............         110,500
Existing TC Holders............  Develop ICA......  ............................          15,743         868,699
Future TC Applicants...........  Develop ICA......  ............................           3,578         197,434
Future STC Applicants..........  Develop ICA......  ............................          57,828       3,190,949
Airplane Manufacturers.........  Revise SWPM......  ............................           1,035          57,111
Airplane Manufacturers.........  Develop            ............................             132           7,284
                                  Compliance Plan.
Airplane Operators.............  Revise             ............................           2,744         151,414
                                  Maintenance
                                  Program.
Airplane Operators.............  Develop Training   ............................           2,376         131,108
                                  Program.
                                                                                 -----------------
    Total......................  .................  ............................         113,899       5,875,522
----------------------------------------------------------------------------------------------------------------

    Proposed Sec.  25.1711 would affect airplane manufacturers by 
requiring additional labeling. Over the 25-year period of analysis, 
manufacturers would label on average 413 airplanes yearly. The FAA 
estimates that an additional 3,500 labels might be added to wires in 
each part 25 airplane, for 1,445,500 labels annually. The additional 
identification requirement would take roughly 30 seconds, requiring 
approximately 12,046 annual hours. Using the fully burdened hourly cost 
of a mechanic ($35.74), the average annual hourly burden for the wire 
identification requirement on manufacturers is $430,524.
    The estimated cost resulting from information collection from TC 
holders also considers the additional cost of labels. The additional 
manufacturer identification requirements would require roughly 
1,445,500 labels annually. Industry representatives provided the FAA 
with cost estimates for each label of approximately 5 cents. The 
estimated annual corresponding cost is $72,275.
    Section 25.1711 would also affect airplane modifiers when 
electrical wiring supplemental type certificates (STC) are installed on 
airplanes. The FAA estimates there would be an additional 200 labels 
added each time an affected STC is installed on an airplane. Using 170 
as the average annual affected number of STCs, and 65 as the number of 
installations per STC, the corresponding total annual number of labels 
for STCs is 2,210,000. The identification requirement would take about 
30 seconds for each additional label, requiring an annual burden of 
roughly 18,417 hours. Using the fully burdened hourly cost of a 
mechanic ($35.74), the annual burden on airplane modifiers for the wire 
identification requirement is $658,224.
    Estimated costs resulting from information collection from STC 
applicants consider the additional cost of labels. The additional STC 
identification requirements would require roughly 2,210,000 labels 
annually. With the cost of each label approximately 5 cents, the 
estimated average annual corresponding cost is $110,500.
    The proposal would require that existing TC holders develop ICA for 
EWIS. Over the period of analysis, the FAA estimates the proposal would 
require 15,743 average annual engineering hours, resulting in an 
average annual cost of $868,699 (using the fully burdened hourly rate 
of $55.18 for an engineer).
    Proposed Sec. 25.1805 would also require future TC applicants to 
develop ICA for EWIS. The FAA estimates roughly .5 part 25 TCs yearly, 
with average annual estimated labor hours to perform the analysis of 
3,578. This would result in average annual costs of $197,434.
    The proposal would require future applicants for STCs to develop 
ICA for EWIS as well. Over the period of analysis, the FAA estimates it 
would take 948 annual STC applicants 61 hours to perform the analysis. 
With engineering costs of $55.18 per hour, the average annual burden 
would be $3,190,949.
    Because of this proposal, manufacturers would change their Standard 
Wiring Practices Manual (SWPM). The FAA calculates 1,035 as the average 
annual hours required to update manuals, resulting in an average annual 
burden of roughly $57,111.
    Manufacturers would present a plan for approval describing how they 
intend to comply with the requirements. The FAA believes the data 
contained in this plan would be submitted electronically with no cost 
to submit the plan. We estimate 60 labor hours (per airplane model) to 
develop a plan and submit data to the FAA. We estimate 3,300 hours for 
roughly 55 models. The average annual hours are 132, with corresponding 
average annual costs of $7,284 (using the fully burdened hourly cost of 
$55.18).
    Operators would be required to revise their existing maintenance 
program to incorporate the maintenance and inspection tasks for EWIS 
contained in the EWIS ICA. Over the period of analysis, the FAA 
estimates 68,607 total hours, or 2,744 average annual hours required to 
revise existing maintenance programs. Using the fully burdened labor 
cost for an engineer, the average annual planning cost would be 
$151,414.
    The estimated cost to develop training considers the industry's 
standard training factor of 200 hours per one hour of prepared training 
material. 600 hours is the estimated training development time for the 
3-hour training course for each operator. When combined with 99 
operators, the total hours would be 59,400 or 2,376 annually. Combined 
with the burdened hourly cost of $55.18, the average annual cost for 
training development would be $131,108.
    The agency is soliciting comments to (1) evaluate whether the 
proposed collection of information is necessary for the proper 
performance of the functions of the agency, including whether the 
information will have practical utility; (2) evaluate the accuracy of 
the agency's estimate of the burden; (3) enhance the quality, utility, 
and clarity of the information to be collected; and (4) minimize the 
burden of the collection of information on those who are to respond, 
including through the use of appropriate automated, electronic, 
mechanical, or other technological collection techniques or other forms 
of information technology (for example, permitting electronic 
submission of responses).
    Individuals and organizations may submit comments on the 
information collection requirement by December 5, 2005, and should 
direct them to the address listed in the ADDRESSES section of this 
document.
    According to the regulations implementing the Paperwork Reduction

[[Page 58542]]

Act of 1995, (5 CFR Part 1320.8(b)(2)(vi)), an agency may not conduct 
or sponsor, and a person is not required to respond to, a collection of 
information unless it displays a currently valid OMB control number. 
The OMB control number for this information collection will be 
published in the Federal Register after it is approved by the Office of 
Management and Budget.

International Compatibility

    In keeping with U.S. obligations under the Convention on 
International Civil Aviation, it is FAA policy to comply with 
International Civil Aviation Organization (ICAO) Standards and 
Recommended Practices to the maximum extent practicable. The FAA has 
determined that there are no ICAO Standards and Recommended Practices 
that correspond to these proposed regulations.

Regulatory Evaluation Summary

    This portion of the preamble summarizes the FAA's analysis of the 
economic impacts of this NPRM. It also includes summaries of the 
initial regulatory flexibility determination. We suggest readers 
seeking greater detail read the full regulatory evaluation, a copy of 
which we have placed in the docket for this rulemaking.
    Changes to Federal regulations must undergo several economic 
analyses. First, Executive Order 12866 directs that each Federal agency 
shall propose or adopt a regulation only upon a reasoned determination 
that the benefits of the intended regulation justify its costs. Second, 
the Regulatory Flexibility Act of 1980 requires agencies to analyze the 
economic impact of regulatory changes on small entities. Third, the 
Trade Agreements Act (19 U.S.C. 2531-2533) prohibits agencies from 
setting standards that create unnecessary obstacles to the foreign 
commerce of the United States. In developing U.S. standards, this Trade 
Act requires agencies to consider international standards and, where 
appropriate, to be the basis of U.S. standards. Fourth, the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4) requires agencies to 
prepare a written assessment of the costs, benefits, and other effects 
of proposed or final rules that include a Federal mandate likely to 
result in the expenditure by State, local, or tribal governments, in 
the aggregate, or by the private sector, of $100 million or more 
annually (adjusted for inflation).
    In conducting these analyses, FAA has determined this proposal: Has 
benefits that justify its costs, is not an economically ``significant 
regulatory action'' as defined in section 3(f) of Executive Order 
12866, and is ``significant'' as defined in DOT's Regulatory Policies 
and Procedures; would not have a significant economic impact on a 
substantial number of small entities; would not have an effect on 
international trade; and would not impose an unfunded mandate on state, 
local, or tribal governments, or on the private sector. These analyses, 
available in the docket, are summarized below.

Total Costs and Benefits of This Rulemaking

    The estimated cost of this NPRM is $474.4 million ($209.2 million 
present value) over 25 years. The total estimated benefits are $755.3 
million ($340.7 million present value) over 25 years.

Who Is Potentially Affected by This Rulemaking?

     Manufacturers of part 25 airplanes.
     Operators of large transport category airplanes operating 
under FAR Parts 121 & 129.
     Applicants for amended type certificates and supplemental 
type certificates.

Cost Assumptions and Sources of Information

Discount rate--7%
Period of analysis--25 Years, 2005 through 2029
Burdened labor rate (as shown in key assumptions & labor rates in 
regulatory evaluation)--
     Aerospace engineers--$55.18/hour
     Maintenance personnel--$35.74/hour
Value of fatality avoided--$3.0 million (Source: ``Revised Departmental 
Guidance, Treatment of Value of Life and Injuries in Preparing Economic 
Evaluations,'' Office of the Secretary of Transportation Memorandum'', 
January 29, 2002)
    Fleet--FAA Flight Standards (SPAS Database)
    Fleet Growth (3.82% per year) & Passenger Occupancy Rates (75%)--
FAA Aerospace Forecasts Years 2003-2014
    Failures, Incidents and Accidents--The National Aviation Safety 
Data Analysis Center
    Aircraft Value--Economic Values for Evaluation of Federal Aviation 
Administration Investment and Regulatory Programs 1998

Articles Referenced

Wright, T.P. ``American Methods of Aircraft Production,'' 1939.
Wojcik, Leonard A., ``Models To Understand Airline and Air Traffic 
Management Authority Decision-Making Interactions in Schedule 
Disruptions: From Simple Games to Agent-Based Models,'' Handbook of 
Airline Strategy, 1992.
Irrgang, M.E., ``Airline Irregular Operations,'' Handbook of Airline 
Economics, 1995.

Alternatives We Considered

    Alternative 1--Require operators to clean & inspect each airplane 
every C-check or every three years, causing an additional $192.5 
million ($79.9 million present value) in cleaning and inspection costs, 
and an additional $104.0 million ($38.6 million present value) in 
downtime.
    This option would result in additional costs of $296.5 million 
($118.5 million present value) with no commensurate increase in 
benefits.
    Alternative 2--Require EWIS training for four groups of people in 
addition to maintenance workers. The groups and additional costs are:
     Electrical/avionic engineers--$4.0 million ($2.4 million 
present value).
     Individuals involved in engineering or planning work--$0.4 
million ($0.4 million present value).
     Flight deck crew--$260.0 million ($126.1 million present 
value).
     Cabin crew-$91.5 million ($44.4 million present value).
    To train these individuals, operators would develop additional 
courses. The FAA estimates an additional $25.2 million ($24.1 million 
present value) to develop the necessary training material.
    The total estimated additional cost of this alternative is 
approximately $381.1 million ($197.4 million present value) with no 
commensurate increase in benefits.

Benefits of This Rulemaking

    The FAA estimates $755.3 million ($340.7 million present value) as 
the total benefits of this proposal.
    In the table below, categories of benefits are shown. The middle 
column gives the nominal values of quantified benefits, while the 
right-hand column gives the total incremental present value benefits 
broken down by category type.

[[Page 58543]]



------------------------------------------------------------------------
                                              Nominal
                Benefits                      values       Present value
                                            (millions)      (millions)
------------------------------------------------------------------------
Non Fatal & Fatal Accidents:
    Non Fatal events....................           $56.0           $26.1
    Fatal events........................           507.0           236.3
                                         -----------------
        Total...........................           563.0           262.4
                                         =================
EWIS Operational Improvements:
    Averted delays......................            21.2             8.3
    Averted unscheduled landings........           152.4            62.4
    Averted IFE failures................            18.7             7.6
                                         -----------------
        Total...........................           192.3            78.3
                                         =================
            Total--All Benefits.........           755.3           340.7
------------------------------------------------------------------------

Costs of This Rulemaking

    The FAA estimates $474.3 million ($209.2 million present value) as 
the total cost of this proposal.
    In the table below, the left-hand column specifies the cost 
component by 14 CFR part, the middle column gives the nominal cost, and 
the right-hand column gives the total incremental present value costs 
by 14 CFR part.

------------------------------------------------------------------------
                                              Nominal
             Cost component                   values      Present  value
                                            (millions)       (millions)
------------------------------------------------------------------------
Part 25 Harmonization...................               0               0
Part 25 Subpart H.......................          $131.9           $53.8
Part 25 Subpart I.......................            23.3            20.3
Part 121 ICA............................           319.1           135.1
Parts 91/121/125--Fuel Tank.............             (*)
                                         -----------------
  Total.................................           474.3          209.2
------------------------------------------------------------------------
* De minimus.

Initial Regulatory Flexibility Determination

    The Regulatory Flexibility Act of 1980 (RFA) establishes ``as a 
principle of regulatory issuance that agencies shall endeavor, 
consistent with the objective of the rule and of applicable statutes, 
to fit regulatory and informational requirements to the scale of the 
business, organizations, and governmental jurisdictions subject to 
regulation.'' To achieve that principle, the RFA requires agencies to 
solicit and consider flexible regulatory proposals and to explain the 
rationale for their actions. The RFA covers a wide-range of small 
entities, including small businesses, not-for-profit organizations, and 
small governmental jurisdictions.
    Agencies must perform a review to determine whether a proposed or 
final rule will have a significant economic impact on a substantial 
number of small entities. If the agency determines that it will, the 
agency must prepare a regulatory flexibility analysis as described in 
the Act.
    However, if an agency determines that a proposed or final rule is 
not expected to have a significant economic impact on a substantial 
number of small entities, section 605(b) of the 1980 RFA provides that 
the head of the agency may so certify and a regulatory flexibility 
analysis is not required. The certification must include a statement 
providing the factual basis for this determination, and the reasoning 
should be clear.
    This proposed rule would not have a significant economic impact on 
a substantial number of small entities for the following reasons.
    Entities potentially affected by this proposal include part 25 
manufacturers, applicants for future amended and supplemental type 
certificates, and part 121 operators of large transport category 
airplanes.
    The FAA uses the size standards from the Small Business 
Administration for Air Transportation and Aircraft Manufacturing, which 
specify companies having less than 1,500 employees as small entities.
    The current United States part 25 airplane manufacturers include: 
Boeing, Cessna Aircraft, Gulfstream Aerospace, Learjet (owned by 
Bombardier), Lockheed Martin, McDonnell Douglas (a wholly-owned 
subsidiary of The Boeing Company), Raytheon Aircraft, and Sabreliner 
Corporation. These manufacturers would incur type certificate (TC) and 
amended TC costs. Because all U.S. transport-aircraft category 
manufacturers have more than 1,500 employees, none are considered small 
entities.
    Future supplemental type certificate (STC) applicants would incur 
additional compliance costs. These STC applicants would incur the cost 
only if the expected revenue from the STC would exceed the expected 
cost. While future STC costs would be passed on to airplane operators, 
it is not possible to determine when and which operator would purchase 
and install such a future STC. Because a future STC applicant would 
incur the additional compliance cost only if the STC would generate 
profits, the FAA believes there would not be a significant impact on a 
substantial number of STC applicants.
    The FAA calculated the economic impact on small-business part 121 
operators by dividing the annual compliance cost by the firm's annual 
revenue. The annual estimated average annual cost of the proposal would 
approach \1/2\ of 1 percent for only two small entities. For the 
others, the cost impact would be a few hundredths of 1 percent of 
revenue.

[[Page 58544]]

    The FAA has determined that: No part 25 manufacturers are small 
entities, there would not be a significant impact on a substantial 
number of amended TC or STC applicants, the estimated operator 
compliance cost as a percent of annual revenue would not be 
significant.
    Accordingly, pursuant to the Regulatory Flexibility Act, 5 U.S.C. 
605(b), the Federal Aviation Administration certifies that this 
proposed rule would not have a significant impact on a substantial 
number of small entities.

Initial International Trade Impact Assessment

    The Trade Agreement Act of 1979 prohibits Federal agencies from 
establishing any standards or engaging in related activities that 
create unnecessary obstacles to the foreign commerce of the United 
States. Legitimate domestic objectives, such as safety, are not 
considered unnecessary obstacles. The statute also requires 
consideration of international standards and, where appropriate, that 
they be the basis for U.S. standards. The FAA has assessed the 
potential effect of this proposed rule and determined that it would 
impose the same costs on domestic and international entities and, thus, 
would have a neutral trade impact.

Initial Unfunded Mandates Assessment

    The Unfunded Mandates Reform Act of 1995 (the Act) is intended, 
among other things, to curb the practice of imposing unfunded Federal 
mandates on State, local, and tribal governments. Title II of the Act 
requires each Federal agency to prepare a written statement assessing 
the effects of any Federal mandate in a proposed or final agency rule 
that may result in an expenditure of $100 million or more (adjusted 
annually for inflation) in any one year by State, local, and tribal 
governments, in the aggregate, or by the private sector; such a mandate 
is deemed to be a ``significant regulatory action.'' The FAA currently 
uses an inflation-adjusted value of $120.7 million in lieu of $100 
million. This proposed rule does not contain such a mandate. Therefore, 
the requirements of Title II of the Unfunded Mandates Reform Act of 
1995 do not apply.

Executive Order 13132, Federalism

    The FAA has analyzed this proposed rule under the principles and 
criteria of Executive Order 13132, Federalism. We determined that this 
action would not have a substantial direct effect on the States, on the 
relationship between the national Government and the States, or on the 
distribution of power and responsibilities among the various levels of 
government, and therefore would not have federalism implications.

Plain English

    Executive Order 12866 (58 FR 51735, Oct. 4, 1993) requires each 
agency to write regulations that are simple and easy to understand. We 
invite your comments on how to make these proposed regulations easier 
to understand, including answers to questions such as the following:
     Are the requirements in the proposed regulations clearly 
stated?
     Do the proposed regulations contain unnecessary technical 
language or jargon that interferes with their clarity?
     Would the regulations be easier to understand if they were 
divided into more (but shorter) sections?
     Is the description in the preamble helpful in 
understanding the proposed regulations?

Please send your comments to the address specified in the ADDRESSES 
section.

Environmental Analysis

    FAA Order 1050.1E identifies FAA actions that are categorically 
excluded from preparation of an environmental assessment or 
environmental impact statement under the National Environmental Policy 
Act in the absence of extraordinary circumstances. The FAA has 
determined this proposed rulemaking action qualifies for the 
categorical exclusion identified in paragraph 312f and involves no 
extraordinary circumstances.

Regulations That Significantly Affect Energy Supply, Distribution, or 
Use

    The FAA has analyzed this NPRM under Executive Order 13211, Actions 
Concerning Regulations that Significantly Affect Energy Supply, 
Distribution, or Use (May 18, 2001). We have determined that it is not 
a ``significant energy action'' under the executive order because it is 
not a ``significant regulatory action'' under Executive Order 12866, 
and it is not likely to have a significant adverse effect on the 
supply, distribution, or use of energy.
    The following Appendices will not appear in the Code of Federal 
Regulations.

Appendix A

List of Acronyms

AC--Advisory Circular
ACJ--Advisory Circular Joint
ACO--Aircraft certification office
AD--Airworthiness directive
AFM--Airplane flight manual
ARAC--Aviation Rulemaking Advisory Committee
ASTF--Aging Systems Task Force
ATA--Air Transport Association
ATSRAC--Aging Transport Systems Rulemaking Advisory Committee
CFR--Code of Federal Regulations
CS--Certification Specifications
CWT--Center wing fuel tank
DET--detailed inspection
EAPAS--Enhanced Airworthiness Program for Airplane Systems
EASA--European Aviation Safety Agency
EUROCAE--European Organization for Civil Aviation Equipment
EWIS--Electrical wiring interconnection systems
EZAP--Enhanced zonal analysis procedure
FAA--Federal Aviation Administration
FQIS--Fuel quantity indicating system
FSDO--Flight Standards District Office
GVI--General visual inspection
ICA--Instructions for Continued Airworthiness
ICAO--International Civil Aviation Organization
IFE--In-flight entertainment
IIWG--Intrusive Inspection Working Group
JAA--Joint Aviation Authority
JAR--Joint Aviation Requirements
MS--Military specification
NPRM--notice of proposed rulemaking
NTSB--National Transportation Safety Board
OMB--Office of Management and Budget
RTCA--Radio Technical Commission for Aeronautics
SAE--Society of Automotive Engineers
SCR--Special certification review
SFAR--Special federal aviation regulation
SFAR 88--Special Federal Aviation Regulation 88--Fuel Tank System 
Fault Tolerance Evaluation Requirements--TC- and STC-holder 
requirements included in the FTSR
STC--Supplemental type certificate
SWAMP--Severe wind and moisture problem
SWPM--Standard wiring practices manual
TC--Type certificate
TSB--Transportation Safety Board of Canada
WHCSS--White House Commission on Aviation Safety and Security

Appendix B

                  Correlation Between Proposed New Part 25 Regulations and Existing Regulations
----------------------------------------------------------------------------------------------------------------
   Proposed new regulation and title                  Section                 Based on existing  requirements in
----------------------------------------------------------------------------------------------------------------
Sec.   25.1701 Definition.............  (a)................................  none

[[Page 58545]]

 
                                        (b)................................  none
                                        (c)................................  none
                                        (d)................................  none
Sec.   25.1703 Function and             (a)(1).............................  Sec.   25.1301(a)
 installation: EWIS.
                                        (a)(2).............................  Sec.   25.1301(c)
                                        (a)(3).............................  Sec.   25.1301(d)
                                        (a)(4).............................  none
                                        (b)................................  none
                                        (c)................................  Sec.   25.869(a)(3)
                                        (d)................................  none
Sec.   25.1705 System safety: EWIS....  (a)(1).............................  Sec.   25.1309(b)(1)
                                        (a)(2).............................  Sec.   25.1309(b)(1)
                                        (b)................................  Sec.   25.1309(b)(2)
Sec.   25.1709 System separation: EWIS  (a)................................  Sec.   25.1353(a)
                                        (b)(1).............................  Sec.   25.1353(a)
                                        (b)(2).............................  none
                                        (c)................................  Sec.   25.1353(b)
                                        (d)(1).............................  Sec.   25.1351(b)(1)
                                        (d)(2).............................  Sec.   25.1351(b)(2)
                                        (e)(1).............................  Sec.   25.869(a)(3)(i)
                                        (e)(2).............................  Sec.   25.869(a)(3)(ii)
                                                                             Sec.   25.1353(d)(3)
                                        (f)(1).............................  Sec.   25.869(a)(3)(i)
                                        (f)(2).............................  Sec.   25.869(a)(3)(ii)
                                                                             Sec.   25.1353(d)(3)
                                        (g)................................  Sec.   25.1353(d)(3)
                                        (h)(1).............................  Sec.   25.1353(d)(3)
                                        (h)(2).............................
                                        (i)(1).............................  Sec.   25.1353(d)(3)
                                        (i)(2).............................
                                        (i)(3).............................
                                        (j)(1).............................  Sec.   25.1353(d)(3)
                                        (j)(2).............................
                                        (k)................................  none
                                        (l)................................  Sec.   25.1353(d)(3)
Sec.   25.1711 Component
 identification: EWIS.
                                        (a)................................  Sec.   25.1301(b)
                                        (b)(1).............................  none
                                        (b)(2).............................  none
                                        (c)................................  Sec.   25.1353(d)(2)
                                        (d)................................  none
                                        (e)................................  none
Sec.   25.1713 Fire protection: EWIS..  (a)................................  Sec.   25.869(a)(1)
                                        (b)................................  Sec.   25.869(a)(2)
                                        (c)................................  Sec.   25.869(a)(4)
Sec.   25.1717 Electrical bonding and   (a)................................  Sec.   25.899
 protection against static
 electricity: EWIS.
                                        (b)................................  none
Sec.   25.1719 Systems and functions:   (a)................................  none
 EWIS.
                                        (b)(1).............................  Sec.   25.773(b)(2)
                                        (b)(2).............................  Sec.   25.981
                                        (b)(3).............................  Sec.   25.1165
                                        (b)(4).............................  Sec.   25.1310
                                        (b)(5).............................  Sec.   25.1316
                                        (b)(6).............................  Sec.   25.1351
                                        (b)(7).............................  Sec.   25.1355
                                        (b)(8).............................  Sec.   25.1360
                                        (b)(9).............................  Sec.   25.1362
                                        (b)(10)............................  Sec.   25.1365
                                        (b)(11)............................  Sec.   25.1431(c)
                                                                             Sec.   25.1431(d)
Sec.   25.1721 Circuit protection       ...................................  Sec.   25.1353(d)(1)
 devices: EWIS.
Sec.   25.1723 Instruments using a      ...................................  Sec.   25.1331(a)(2)
 power supply: EWIS.                                                         Sec.   25.1303(b)
Sec.   25.1725 Accessibility            ...................................  Sec.   25.611
 provisions: EWIS.
Sec.   25.1727 Protection of EWIS.....  (a)(1).............................  Sec.   25.855(e)(1)
                                        (a)(2).............................  Sec.   25.855(e)(2)
                                        (b)................................  none
                                        (c)................................  none
Sec.   25.1729 Flammable fluid fire     ...................................  Sec.   25.863(b)(3)
 protection: EWIS.
Sec.   25.1731 Powerplants: EWIS......  (a)................................  Sec.   25.903(b)
                                        (b)................................  Sec.   25.903(d)(1)

[[Page 58546]]

 
Sec.   25.1733 Flammable fluid shutoff  ...................................  Sec.   25.1189(d)
 means: EWIS.
Sec.   25.1735 Fire detector systems,   ...................................  none
 general: EWIS.
Sec.   25.1737 Powerplant and APU fire  (a)................................  Sec.   25.1203(e)
 detector system: EWIS.
                                        (b)(1).............................  Sec.   25.1203(f)(1)
                                        (b)(2).............................  Sec.   25.1203(f)(2)
Sec.   25.1739 Instructions for         ...................................  Sec.   25.1529
 Continued Airworthiness: EWIS.
----------------------------------------------------------------------------------------------------------------
The term ``none'' in the above table indicates that the section in the proposed regulation is a new rule.

Appendix C

                  Correlation Between Existing Part 25 Regulations and Proposed New Regulations
----------------------------------------------------------------------------------------------------------------
     Existing regulation and title                    Section                      Proposed new  regulation
----------------------------------------------------------------------------------------------------------------
Sec.   25.611 Accessibility provisions  ...................................  Sec.   25.1725
Sec.   25.773 Pilot compartment view..  (b)(2).............................  Sec.   25.1719(b)(1)
Sec.   25.855 Cargo or baggage          (e)(1).............................  Sec.   25.1727(a)(1)
 compartments.
                                        (e)(2).............................  Sec.   25.1727(a)(2)
Sec.   25.863 Flammable fluid fire      (b)(3).............................  Sec.   25.1729
 protection.
Sec.   25.869 Fire protection: systems  (a)(1).............................  Sec.   25.1713(a)
                                        (a)(2).............................  Sec.   25.1713(b)
                                        (a)(4).............................  Sec.   25.1713(c)
                                        (a)(3)(i)..........................  Sec.   25.1709(e)(1)
                                        (a)(3)(ii).........................  Sec.   25.1709(e)(2)
                                                                             Sec.   25.1709(f)(1)
                                                                             Sec.   25.1709(f)(2)
                                        (a)(4).............................  Sec.   25.1713(c)
Sec.   25.899 Electrical bonding and    ...................................  Sec.   25.1717(a)
 protection against static electricity.
Sec.   25.903 Engines.................  (b)................................  Sec.   25.1731(a)
                                        (d)(1).............................  Sec.   25.1731(b)
Sec.   25.1165 Engine ignition systems  ...................................  Sec.   25.1719(b)(3)
Sec.   25.1189 Shutoff means..........  (d)................................  Sec.   25.1733
Sec.   25.1203 Fire detector system...  (e)................................  Sec.   25.1737(a)
                                        (f)(1).............................  Sec.   25.1737(b)(1)
                                        (f)(2).............................  Sec.   25.1737(b)(2)
Sec.   25.1301 Function and             (a)................................  Sec.   25.1703(a)(1)
 installation.
                                        (c)................................  Sec.   25.1703(a)(2)
                                        (b)................................  Sec.   25.1711(a)
                                        (d)................................  Sec.   25.1703(a)(3)
Sec.   25.1303 Flight and navigation    (b)................................  Sec.   25.1723
 instruments.
Sec.   25.1309 Equipment, systems, and  (b)(1).............................  Sec.   25.1705(a)(1)
 installations.                                                              Sec.   25.1705(a)(2)
                                        (b)(2).............................  Sec.   25.1705(b)
                                        (e)................................  Sec.   25.1707
                                        (f)................................  Sec.   25.1707
Sec.   25.1316 System lightning         ...................................  Sec.   25.1719(b)(5)
 protection.
Sec.   25.1331 Instruments using a      (a)(2).............................  Sec.   25.1723
 power supply.
Sec.   25.1351 General................  (b)(1).............................  Sec.   25.1709(d)(1)
                                        (b)(2).............................  Sec.   25.1709(d)(2)
Sec.   25.1353 Electrical equipment     (a)................................  Sec.   25.1709(b)(1)
 and installations.
                                        (a)................................  Sec.   25.1709(a)
                                        (b)................................  Sec.   25.1709(c)
                                        (d)(1).............................  Sec.   25.1721
                                        (d)(2).............................  Sec.   25.1711(c)
                                        (d)(3).............................  Sec.   25.1709(e)(1)
                                                                             Sec.   25.1709(e)(2)
                                        (d)(3).............................  Sec.   25.1709(f)(1)
                                                                             Sec.   25.1709(f)(2)
                                        (d)(3).............................  Sec.   25.1709(g)
                                        (d)(3).............................  Sec.   25.1709(h)(1)
                                                                             Sec.   25.1709(h)(2)
                                        (d)(3).............................  Sec.   25.1709(i)(1)
                                                                             Sec.   25.1709(i)(2)
                                                                             Sec.   25.1709(i)(3)
                                        (d)(3).............................  Sec.   25.1709(j)(1)
                                                                             Sec.   25.1709(j)(2)
                                        (d)(3).............................  Sec.   25.1709(l)
Sec.   25.1355 Distribution system....  ...................................  Sec.   25.1719(b)(5)

[[Page 58547]]

 
Sec.   25.1360 Precautions against      ...................................  Sec.   25.1719(b)(6)
 injury.
Sec.   25.1362 Electrical supplies for  ...................................  Sec.   25.1719(b)(7)
 emergency conditions.
Sec.   25.1365 Electrical appliances,   ...................................  Sec.   25.1719(b)(8)
 motors, and transformers.
Sec.   25.1431 Electronic equipment...  (c)................................  Sec.   25.1719(b)(9)
                                        (d)................................  ...................................
Sec.   25.1529 Instructions for         ...................................  Sec.   25.1739
 Continued Airworthiness.
----------------------------------------------------------------------------------------------------------------

Appendix D

    The tables below indicate which of the current rules will need 
to be changed to accommodate the new certification requirements and 
which will remain the same.

              Existing Part 25 Requirements Requiring Revision To Support New Proposed Regulations
----------------------------------------------------------------------------------------------------------------
                    Existing regulation                          Revision to existing  regulation  required?
----------------------------------------------------------------------------------------------------------------
Sec.   25.611..............................................  Yes.
Sec.   25.773..............................................  No.
Sec.   25.855..............................................  Yes.
Sec.   25.863..............................................  No.
Sec.   25.869..............................................  Yes.
Sec.   25.899..............................................  No.
Sec.   25.903..............................................  No.
Sec.   25.1165.............................................  No.
Sec.   25.1189.............................................  No.
Sec.   25.1203.............................................  Yes.
Sec.   25.1301.............................................  Yes.
Sec.   25.1309.............................................  Yes.
Sec.   25.1310.............................................  No.
Sec.   25.1316.............................................  No.
Sec.   25.1331.............................................  No.
Sec.   25.1351.............................................  No.
Sec.   25.1353.............................................  Yes.
Sec.   25.1355.............................................  No.
Sec.   25.1357.............................................  Yes.
Sec.   25.1360.............................................  No.
Sec.   25.1362.............................................  No.
Sec.   25.1365.............................................  No.
Sec.   25.1431.............................................  No.
Sec.   25.1529.............................................  No.
----------------------------------------------------------------------------------------------------------------

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Discussion of the EWIS Safety Analysis Process as Depicted in 
Flowcharts 1 and 2 (Excerpt From Proposed AC 25.17XX, ``Certification 
of Electrical Wiring Interconnection Systems on Transport Category 
Airplanes'')

    The analysis described here is based on a qualitative approach to 
assessing EWIS safety as opposed to numerical, probability-based 
quantitative analysis. The intent is not to examine each individual 
wire and its relation to other wires. Rather, it is to ensure that 
there are no hazardous combinations. However, in case the ``top down'' 
analysis process described in this AC determines that a failure in a 
given bundle may lead to a catastrophic failure condition, the 
mitigation process may lead to performing a complete analysis of each 
wire in the relevant bundle.
    The analysis described may be accomplished in conjunction with the 
required aircraft system safety assessments of Sec. Sec.  25.1309, 
25.671, etc.
    The classification of failure conditions is given in Table 1 (found 
in the section-by-section discussion of proposed Sec.  25.1705).
    There are two flowcharts contained in this appendix:
     Flowchart 1 applies to applicants for pre-TC work and for 
amended TCs, and STCs when the applicant has all data necessary to 
perform the analysis per Flowchart 1. If Flowchart 1 is used for post-
TC modifications the available data must include identification of the 
systems in the EWIS under consideration for modification and the system 
functions associated with that EWIS.
     Flowchart 2 applies to applicants for post-TC 
modifications when the applicant cannot identify the systems or systems 
functions contained in EWIS under consideration for modification
    The analysis process is initiated by a functional hazard analysis 
performed at aircraft level identifying catastrophic and hazardous 
failure events.
    The processes in both Flowcharts 1 and 2 identify two aspects: 
physical and functional failures.


    Note: For this discussion the following definitions apply:
    Validation: Determination that requirements for a product are 
sufficiently correct and complete.
    Verification: Evaluation to determine that requirements have 
been met.


    Physical Failure Analysis: Only single common cause events or 
failures need to be addressed during the physical failure analysis as 
described in this AC and shown on the left hand sides of Flowcharts 1 
and 2. The objective of the physical analysis is to protect against 
single common cause events or failures that may involve single or 
multiple physical failures. Multiple common cause events or failures 
need not be addressed.
    In relation to physical effects, it should be assumed that wires 
are carrying electrical energy and, in the case of an EWIS failure, as 
defined in the preceding paragraph, this energy may result in hazardous 
or catastrophic effects directly or when combined with other factors 
(fuel, oxygen, hydraulic fluid, or damage by passengers, for example). 
These failures, for example, may result in fire, smoke, emission of 
toxic gases, and damage to co-located systems and structural elements 
or injury to personnel. This analysis considers all EWIS from all 
systems regardless of criticality, (autopilot, auto throttle, PA 
system, IFE system, etc.).
    Functional Failure Analysis: The functional failure analysis 
assumes that electrical wires are carrying power, signal, or 
information data. Failure of EWIS under these circumstances may lead to 
aircraft system degradation effects.

Descriptive Text for Flowchart 1

Box A

    The functional hazard assessment (FHA) referred to in this box is 
not a stand-alone separate document specifically created to show 
compliance with Sec.  25.1705. It is the aircraft level FHA that the 
applicant will have developed in compliance with Sec.  25.1309 to help 
demonstrate acceptability of a design concept, identify potential 
problem areas or desirable design changes, or determine the need for 
and scope of any additional analyses (refer to AC/ACJ 25.1309-1B).

Physical Failures

Box B

    EWIS Characteristics: Use the results of the FHA (BOX A) to 
identify EWIS installation criteria and definitions of component 
characteristics. Results of BOX B are fed into the preliminary system 
safety analysis (PSSA) and system safety analysis (SSA) of BOX J.

Boxes C, D, and E

    Validation and Verification of Installation Criteria: Ensure that 
the EWIS component qualification satisfies the design requirements and 
that components are selected, used, and installed according to their 
qualification characteristics and the aircraft constraints linked to 
their location.
    Using available information (e.g., digital mockup, physical mockup, 
aircraft, historical data), inspections and analyses (e.g., 1st article 
inspection, design review, particular risks, zonal safety assessments, 
zonal inspections, common mode analysis, as applicable) should be 
performed to validate that design and installation criteria are 
adequate to the zone/function, including multi-systems impact. Also, 
the inspections and analyses should be used to assess whether design 
and installation criteria were correctly applied. Special consideration 
should be given to those areas of the airplane that are known problem 
areas based on service history and historical data (e.g., arcing, 
smoke, loose clamps, chafing, arc tracking, interference with other 
systems, etc.). Special considerations should also be given to cases 
where new (previously unused) material or other technologies are used.
    Deviations from installation and component selection criteria 
identified by these activities should be evaluated and a determination 
made about their acceptability. Alternative mitigation strategies 
should be developed as necessary.

Boxes F & G

    Development and Validation of Mitigation Strategy: Identify and 
develop a mitigation strategy for the physical failures and their 
adverse effects identified in BOXES D and E.
     Validation and verification of the mitigation solution 
should ensure that:
     Hazardous failure conditions are extremely remote.
     Catastrophic failure conditions do not result from a 
single common cause event or failure.
     This mitigation solution does not introduce any new 
potential failure conditions.

Box H

    Incorporate newly developed mitigation strategies (BOX F) into 
guidelines (BOX B) for further design and inspection and analysis 
process.

Box I

    From the EWIS physical failure analysis, document the physical 
failures that were addressed, their effects, and the mitigation 
strategies that were developed. This information supports the final 
analysis documentation (BOX P).

Functional Failures

Box J

    System Safety Assessment: Use results of the aircraft level FHA 
(BOX A) to guide the system level FHA (BOX J).
    EWIS failures identified by Sec.  25.1705 are to be incorporated 
into the system

[[Page 58551]]

level and aircraft level FHA, as necessary, the PSSA, the common cause 
analysis (CCA), and the SSA. These analyses are performed to satisfy 
requirements of Sec.  25.1309.
    Use results of these analyses to update the EWIS definition (BOX 
B).

Boxes K, L, and M

    Hazardous and Catastrophic Failure Conditions: Use the analyses in 
BOX J to determine if the EWIS associated with the system under 
analysis can contribute (in whole or in part) to the failure condition 
under study. A determination needs to be made about whether the EWIS 
failure needs to be mitigated. If yes, a mitigation strategy needs to 
be developed, validated, and verified. If no, the appropriate safety 
assessment should be completed (e.g., per Sec.  25.1309, Sec.  25.671, 
etc.).

Boxes N and O

    Development and Validation of Mitigation Strategy: Identify and 
develop a mitigation strategy for the functional failures and adverse 
effects identified in BOX J.
    Validation and verification of the mitigation solution should 
determine if initial objective is fully reached and confirm that this 
mitigation solution is compatible with existing installations and 
installation criteria. If the EWIS was the failure cause, the 
subsequent mitigation strategy developed may introduce new adverse 
effects not previously identified by the analysis. A check for any new 
adverse effects should be accomplished and the aircraft level FHA and 
other system safety assessments should be updated as necessary.

Box P

    After the mitigation strategies have been validated and verified, 
document the results of the Sec.  25.1705 analysis. Update as necessary 
the aircraft level FHA that has been developed in support of 
certification of the proposed modification, in compliance with Sec.  
25.1309, (BOX A).

Descriptive Text for Flowchart 2

    The main objectives are to ensure that the proposed modification 
will be correctly designed and installed and will not adversely affect 
existing systems.
    As far as EWIS is concerned, correct incorporation of the 
modification should be ensured by both good knowledge of original 
aircraft manufacturer (OAM) installation practices and their correct 
implementation or by adequate separation of the added EWIS from 
existing EWIS. In either case, physical analyses should be performed 
(similar to the physical failures part of Flowchart 1).

Box A

    Aircraft level effects must be considered for modified systems or 
systems added to the aircraft. If the applicant has the aircraft level 
FHA it should be examined to determine the airplane-level effect of the 
proposed modification. If the applicant doesn't have the aircraft level 
FHA, then the applicant must generate an aircraft level FHA based on 
the proposed modification. This aircraft level FHA would be limited to 
just those aircraft systems affected by the proposed modification. If 
it is determined that no aircraft level functional effects are 
introduced, a statement to this effect and the supporting data is 
sufficient to satisfy BOX A.

Physical Failures

Box B

    EWIS Characteristics: Use results of the aircraft level FHA (BOX A) 
to identify EWIS installation criteria and definitions of component 
characteristics. Results of BOX B are fed into the PSSA and SSA of BOX 
J.

Box C

    Separate the EWIS to be added from other existing airplane EWIS 
since it cannot be determined what systems or system functions are 
contained in the existing EWIS. Physical separation between the new and 
existing EWIS must be achieved through separation distance or an 
appropriate barrier or other means shown to be at least equivalent to 
the physical separation distance when allowed by Sec.  25.1709. Methods 
given in the proposed advisory material for Sec.  25.1709 provide an 
acceptable way to determine adequate separation.
    In cases where separation cannot be maintained because of physical 
constraints (e.g., terminal strips and connectors, etc.), the applicant 
should accomplish the appropriate analysis to show that no adverse 
failure conditions exist because of sharing the common device. This 
requires that the applicant have knowledge of the systems or system 
functions sharing the common device (e.g. terminal strips and 
connectors etc.).

Boxes D and E

Validation and Verification of Installation Criteria
    Ensure that the EWIS component qualification satisfies the design 
requirements and that components are selected, used, and installed 
according to their qualification characteristics and the aircraft 
constraints linked to their location.
    Using available information (e.g., digital mockup, physical mockup, 
aircraft, historical data), inspections and analyses (e.g. 1st article 
inspection, design review, particular risks, zonal safety assessments, 
zonal inspections, common mode analysis, as applicable) should be 
performed to validate that design and installation criteria are 
adequate to the zone/function, including multi-systems impact. Also, 
inspections and analyses should be used to assess whether design and 
installation criteria were correctly applied. Special consideration 
should be given to those areas of the airplane that are known problem 
areas based on service history and historical data (e.g., arcing, 
smoke, loose clamps, chafing, arc tracking, interference with other 
systems, etc.). Special consideration should also be given to cases 
where new (previously unused) material or other technologies are used.
    Deviation from installation and component selection criteria 
identified by these activities should be evaluated and a determination 
made about their acceptability. Alternative mitigation strategies 
should be developed as necessary.

Boxes F and G

Development & Validation of Mitigation Strategy
    Identify and develop a mitigation strategy for the physical 
failures and their adverse effects identified in Boxes D and E.
    Validation and verification of the mitigation solution should 
ensure that:
     Hazardous failure conditions are extremely remote.
     Catastrophic failure conditions do not result from a 
single common cause event or failure.
     This mitigation solution does not introduce any new 
potential failure conditions.

Box H

    Incorporate newly developed mitigation strategies (Box F) into 
guidelines (Box B) for further design and inspection and analysis 
process.

Box I

    From the EWIS physical failure analysis, document the physical 
failures that were addressed, their effects, and mitigation strategies 
that were developed. This information supports the final analysis 
documentation (Box P).

[[Page 58552]]

Functional Failures

Box J

System Safety Assessment
    Use the results of the aircraft level FHA (Box A) to guide the 
system level FHA (Box J).
    EWIS failures identified by Sec.  25.1705 are to be incorporated 
into the system level and aircraft level FHA, as necessary, the PSSA, 
the CCA, and the SSA. These analyses are performed to satisfy 
requirements of Sec.  25.1309.
    Use results of these analyses to update the EWIS definition (Box 
B).

Boxes K, L, and M

Hazardous and Catastrophic Failure Conditions
    Use the analyses in Box J to determine if the EWIS associated with 
the system under analysis can contribute (in whole or in part) to the 
failure condition under study. A determination needs to be made about 
whether the EWIS failure needs to be mitigated. If yes, a mitigation 
strategy needs to be developed, validated, and verified. If no, the 
appropriate safety assessment should be completed (e.g., per Sec.  
25.1309, Sec.  25.671, etc.).

Boxes N and O

Development and Validation of Mitigation Strategy
    Identify and develop a mitigation strategy for the functional 
failures and adverse effects identified in Box J.
    Validation and verification of the mitigation solution should 
determine if initial objective is fully reached and confirm that this 
mitigation solution is compatible with existing installations and 
installation criteria. If the EWIS was the failure cause, the 
subsequent mitigation strategy developed may introduce new adverse 
effects not previously identified by the analysis. A check for any new 
adverse effects should be accomplished and the aircraft level FHA and 
other system safety assessments should be updated as necessary.

Box P

    After the mitigation strategies have been validated and verified, 
document the results of the Sec.  25.1705 analysis. Update as necessary 
the aircraft level FHA that has been developed in support of 
certification of the proposed modification, in compliance with Sec.  
25.1309, (Box A).

List of Subjects

14 CFR Part 1

    Air Transportation.

14 CFR Parts 25, 91, 125

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.

14 CFR Parts 121, 129

    Air carriers, Aircraft, Aviation safety, Reporting and 
recordkeeping requirements.

The Proposed Amendments

    In consideration of the foregoing, the Federal Aviation 
Administration proposes to amend Chapter I of Title 14, Code of Federal 
Regulations parts 1, 25, 91, 121, 125, and 129 as follows:

PART 1--DEFINITIONS AND ABBREVIATIONS

    1. The authority citation for part 1 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701.

    2. Amend Sec.  1.2 to add the following abbreviation in 
alphabetical order:


Sec.  1.2  Abbreviations and symbols.

* * * * *
    EWIS means electrical wiring interconnection system.
* * * * *

PART 25--AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES

    3. The authority citation for part 25 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701, 44702 and 44704.

    4. Amend Sec.  25.1 by adding a new paragraph (c) to read as 
follows:


Sec.  25.1  Applicability.

* * * * *
    (c) This part also establishes requirements for holders of type 
certificates and changes to those certificates to take actions 
necessary to support the continued airworthiness of transport category 
airplanes.
    5. Amend Sec.  25.2 by adding a new paragraph (d) to read as 
follows:


Sec.  25.2  Special retroactive requirements.

* * * * *
    (d) In addition to the requirements of this section, subpart I of 
this part contains requirements that apply to--
    (1) Holders of type certificates; and
    (2) Applicants for type certificates, changes to type certificates 
(including service bulletins describing design changes), and 
supplemental type certificates.
    6. Amend Sec.  25.611 by designating the existing paragraph as 
paragraph (a) and adding new paragraph (b) to read as follows:


Sec.  25.611  Accessibility provisions.

    (a) * * *
    (b) EWIS must meet the accessibility requirements of Sec.  25.1725.
    7. Amend Sec.  25.855 by removing the word ``wiring'' from 
paragraph (e) introductory text and adding new paragraph (j) as 
follows:


Sec.  25.855  Cargo or baggage compartments.

* * * * *
    (j) Cargo or baggage compartment electrical wiring interconnection 
system components must meet the requirements of Sec.  25.1727.
    8. Amend Sec.  25.869 by removing paragraph (a)(4) and revising 
paragraphs (a)(2) and (a)(3) as follows:


Sec.  25.869  Fire protection: systems.

    (a) * * *
    (1) * * *
    (2) Equipment that is located in designated fire zones and is used 
during emergency procedures must be at least fire resistant.
    (3) EWIS components must meet the requirements of Sec.  25.1713.
* * * * *
    9. Amend part 25 by adding a new Sec.  25.899 to read as follows:


Sec.  25.899  Electrical bonding and protection against static 
electricity.

    (a) Electrical bonding and protection against static electricity 
must be designed to minimize accumulation of electrostatic charge that 
would cause--
    (1) Human injury from electrical shock,
    (2) Ignition of flammable vapors, or
    (3) Interference with installed electrical/electronic equipment.
    (b) Compliance with paragraph (a) of this section may be shown by--
    (1) Bonding the components properly to the airframe; or
    (2) Incorporating other acceptable means to dissipate the static 
charge so as not to endanger the airplane, personnel, or operation of 
the installed electrical/electronic systems.
    10. Amend Sec.  25.1203 by revising paragraph (e) and adding a new 
paragraph (h) as follows:


Sec.  25.1203  Fire detector system.

* * * * *
    (e) Components of each fire or overheat detector system in a fire 
zone must be at least fire-resistant.
* * * * *
    (h) EWIS for each fire or overheat detector system in a fire zone 
must meet the requirements of Sec.  25.1727.
    11. Amend Sec.  25.1301 by designating the introductory text as 
paragraph (a), redesignating paragraphs (a) through (d) as (1) through 
(4), and adding a new paragraph (b) as follows:

[[Page 58553]]

Sec.  25.1301  Function and installation.

* * * * *
    (b) EWIS must meet the requirements of subpart H of this part.
    12. Amend Sec.  25.1309 by removing paragraph (e) and redesignating 
paragraph (g) as paragraph (e) and revising paragraph (f) as follows:


Sec.  25.1309  Equipment, systems, and installations.

* * * * *
    (f) EWIS must be assessed in accordance with the requirements of 
Sec.  25.1705.
    13. Amend part 25 by adding a new Sec.  25.1310, to read as 
follows:


Sec.  25.1310  Power source capacity and distribution.

    (a) Each installation whose functioning is required for type 
certification or under operating rules and that requires a power supply 
is an ``essential load'' on the power supply. The power sources and the 
system must be able to supply the following power loads in probable 
operating combinations and for probable durations:
    (1) Loads connected to the system with the system functioning 
normally.
    (2) Essential loads, after failure of any one prime mover, power 
converter, or energy storage device.
    (3) Essential loads after failure of--
    (i) Any one engine on two-engine airplanes; and
    (ii) Any two engines on three-or-more-engined airplanes.
    (4) Essential loads for which an alternate source of power is 
required, after any failure or malfunction in any one power supply 
system, distribution system, or other utilization system.
    (b) In determining compliance with paragraphs (a) (2) and (3) of 
this section, the power loads may be assumed to be reduced under a 
monitoring procedure consistent with safety in the kinds of operation 
authorized. Loads not required in controlled flight need not be 
considered for the two-engine-inoperative condition on airplanes with 
three or more engines.
    14. Amend Sec.  25.1353 by revising paragraphs (a), (b), and (d) as 
follows:


Sec.  25.1353  Electrical equipment and installations.

    (a) Electrical equipment and controls must be installed so that 
operation of any one unit or system of units will not adversely affect 
the simultaneous operation of any other electrical unit or system 
essential to safe operation. Any electrical interference likely to be 
present in the airplane must not result in hazardous effects on the 
airplane or its systems.
    (b) EWIS components must meet the requirements of Sec.  25.1357, 
Sec.  25.1703, Sec.  25.1709, Sec.  25.1711, and Sec.  25.1721.
    (c) * * *
    (d) Electrical bonding must provide an adequate electrical return 
path under both normal and fault conditions, on airplanes having 
grounded electrical systems.
    15. Amend Sec.  25.1357 by revising paragraphs (d) and (f) to read 
as follows:


Sec.  25.1357  Circuit protective devices.

* * * * *
    (d) If the ability to reset a circuit breaker or replace a fuse is 
essential to safety in flight, that circuit breaker or fuse must be 
located and identified so that it can be readily reset or replaced in 
flight. Where fuses are used, there must be spare fuses for use in-
flight equal to at least 50% of the number of fuses of each rating 
required for complete circuit protection.
* * * * *
    (f) For airplane systems for which the ability to remove or reset 
power during normal operations is necessary, the system must be 
designed so that circuit breakers are not the primary means to remove 
or reset system power unless specifically designed for use as a switch.
* * * * *
    16. Amend part 25 by adding a new Sec.  25.1360 to read as follows:


Sec.  25.1360  Precautions against injury.

    (a) Shock. The electrical system must be designed to minimize risk 
of electric shock to crew, passengers, and servicing personnel and to 
maintenance personnel using normal precautions.
    (b) Burns. The temperature of any part that may be handled by a 
crewmember during normal operations must not cause dangerous 
inadvertent movement by the crewmember or injury to the crewmember.
    17. Amend part 25 by adding a new Sec.  25.1362 to read as follows:


Sec.  25.1362  Electrical supplies for emergency conditions.

    A suitable electrical supply must be provided to those services 
required for emergency procedures after an emergency landing or 
ditching. The circuits for these services must be designed, protected, 
and installed so that the risk of their causing a fire under these 
emergency conditions is minimized.
    18. Amend part 25 by adding a new Sec.  25.1365 to read as follows:


Sec.  25.1365  Electrical appliances, motors, and transformers.

    (a) Domestic appliances must be designed and installed so that in 
the event of failures of the electrical supply or control system, the 
requirements of Sec.  25.1309(b), (c), and (d) will be satisfied. 
Domestic appliances are items such as cooktops, ovens, coffee makers, 
water heaters, refrigerators, and toilet flush systems that are placed 
on the airplane to provide service amenities to passengers.
    (b) Galleys and cooking appliances must be installed in a way that 
minimizes risk of overheat or fire.
    (c) Domestic appliances, particularly those in galley areas, must 
be so installed or protected as to prevent damage or contamination of 
other equipment or systems from fluids or vapors which may be present 
during normal operation or as a result of spillage, if such damage or 
contamination may create a hazardous condition.
    (d) Unless compliance with Sec.  25.1309(b) is provided by the 
circuit protective device required by Sec.  25.1357(a), electric motors 
and transformers, including those installed in domestic systems, must 
have a suitable thermal protection device to prevent overheating under 
normal operation and failure conditions, if overheating would create a 
smoke or fire hazard.
    19. Amend part 25 by adding new subpart H to read as follows:
Subpart H--Electrical Wiring Interconnection Systems (EWIS)
Sec.
25.1701 Definition.
25.1703 Function and installation: EWIS.
25.1705 System safety: EWIS.
25.1707 [Reserved]
25.1709 System separation: EWIS.
25.1711 Component identification: EWIS.
25.1713 Fire protection: EWIS.
25.1715 [Reserved]
25.1717 Electrical bonding and protection against static 
electricity: EWIS.
25.1719 Systems and functions: EWIS.
25.1721 Circuit protective devices: EWIS.
25.1723 Instruments using a power supply: EWIS.
25.1725 Accessibility provisions: EWIS.
25.1727 Protection of EWIS.
25.1729 Flammable fluid fire protection: EWIS.
25.1731 Powerplants: EWIS.
25.1733 Flammable fluid shutoff means: EWIS.
25.1735 Fire detector systems, general: EWIS.
25.1737 Powerplant and APU fire detector system: EWIS.
25.1739 Instructions for Continued Airworthiness: EWIS.

Subpart H--Electrical Wiring Interconnection Systems (EWIS)


Sec.  25.1701  Definition.

    (a) As used in this chapter, electrical wiring interconnection 
system (EWIS)

[[Page 58554]]

means any wire, wiring device, or combination of these, including 
termination devices, installed in any area of the airplane for the 
purpose of transmitting electrical energy between two or more intended 
termination points. Except as provided for in paragraph (c) of this 
section, this includes:
    (1) Wires and cables.
    (2) Bus bars.
    (3) The termination point on electrical devices, including those on 
relays, interrupters, switches, contactors, terminal blocks and circuit 
breakers, and other circuit protection devices.
    (4) Connectors, including feed-through connectors.
    (5) Connector accessories.
    (6) Electrical grounding and bonding devices and their associated 
connections.
    (7) Electrical splices.
    (8) Materials used to provide additional protection for wires, 
including wire insulation, wire sleeving, and conduits that have 
electrical termination for the purpose of bonding.
    (9) Shields or braids.
    (10) Clamps and other devices used to route and support the wire 
bundle.
    (11) Cable tie devices.
    (12) Labels or other means of identification.
    (13) Pressure seals.
    (b) The definition in paragraph (a) of this section covers EWIS 
components inside shelves, panels, racks, junction boxes, distribution 
panels, and back-planes of equipment racks, including, but not limited 
to, circuit board back-planes and wire integration units.
    (c) Except for the equipment indicated in paragraph (b) of this 
section, EWIS components inside the following equipment, and the 
external connectors that are part of that equipment, are excluded from 
the definition in paragraph (a) of this section:
    (1) Electrical equipment or avionics that are qualified to 
environmental conditions and testing procedures when those conditions 
and procedures are-(i)
    Appropriate for the intended function and operating environment, 
and
    (ii) Acceptable to the FAA.
    (2) Portable electrical devices that are not part of the type 
design of the airplane. This includes personal entertainment devices 
and laptop computers.
    (3) Fiber optics.


Sec.  25.1703  Function and installation: EWIS.

    (a) Each EWIS component installed in any area of the aircraft must:
    (1) Be of a kind and design appropriate to its intended function.
    (2) Be installed according to limitations specified for the EWIS 
components.
    (3) Function properly when installed.
    (4) Be designed and installed in a way that will minimize 
mechanical strain.
    (b) Selection of wires must take into account known characteristics 
of the wire in relation to each installation and application to 
minimize the risk of wire damage, including any arc tracking phenomena.
    (c) The design and installation of the main power cables, including 
generator cables, must allow for a reasonable degree of deformation and 
stretching without failure.
    (d) EWIS components located in areas of known moisture accumulation 
must be adequately protected to minimize any hazardous effects due to 
moisture.


Sec.  25.1705  System safety: EWIS.

    Each EWIS must be designed and installed so that:
    (a) Each catastrophic failure condition--
    (1) Is extremely improbable; and
    (2) Does not result from a single failure.
    (b) Each hazardous failure condition is extremely remote.


Sec.  25.1707  [Reserved]


Sec.  25.1709  System separation: EWIS.

    (a) Each EWIS must be designed and installed so that under normal 
conditions and failure conditions as defined by Sec.  25.1309(b)(1) and 
(b)(2), it will not adversely affect the simultaneous operation of any 
other systems necessary for continued safe flight, landing, and egress. 
Unless otherwise stated, for the purposes of this section, adequate 
physical separation must be achieved by separation distance or by a 
barrier that provides protection equivalent to that separation 
distance.
    (b) Each EWIS must be designed and installed so that any electrical 
interference likely to be present in the airplane will not result in 
hazardous effects upon the airplane or its systems.
    (c) Wires and cables carrying heavy current, and their associated 
EWIS components, must be designed and installed to ensure adequate 
physical separation and electrical isolation so that damage to 
essential circuits will be minimized under fault conditions.
    (d) Each EWIS associated with independent airplane power sources 
must be designed and installed to ensure adequate physical separation 
and electrical isolation so that a fault in any one airplane power 
source EWIS will not adversely affect any other independent power 
sources. In addition:
    (1) Airplane independent electrical power sources must not share a 
common ground terminating location.
    (2) Airplane system static grounds must not share a common ground 
terminating location with any of the airplane's independent electrical 
power sources.
    (e) Except to the extent necessary to provide electrical connection 
to the fuel systems components, the EWIS must be designed and installed 
with adequate physical separation from fuel lines and other fuel system 
components, so that:
    (1) Any EWIS component failure will not create a hazardous 
condition.
    (2) Any fuel leakage onto EWIS components will not create a 
hazardous condition.
    (f) Except to the extent necessary to provide electrical connection 
to the hydraulic systems components, EWIS must be designed and 
installed with adequate physical separation from hydraulic lines and 
other hydraulic system components, so that:
    (1) Any EWIS component failure will not create a hazardous 
condition.
    (2) Any hydraulic fluid leakage onto EWIS components will not 
create a hazardous condition.
    (g) Except to the extent necessary to provide electrical connection 
to the oxygen systems components, EWIS must be designed and installed 
with adequate physical separation from oxygen lines and other oxygen 
system components, so that any EWIS component failure will not create a 
hazardous condition.
    (h) Except to the extent necessary to provide electrical connection 
to the water/waste systems components, EWIS must be designed and 
installed with adequate physical separation from water/waste lines and 
other water/waste system components, so that:
    (1) Any EWIS component failure will not create a hazardous 
condition.
    (2) Any water/waste leakage onto EWIS components will not create a 
hazardous condition.
    (i) EWIS must be designed and installed with adequate physical 
separation between the EWIS and flight or other mechanical control 
systems cables and associated system components, so that:
    (1) Chafing, jamming, or other interference are prevented.
    (2) Any EWIS component failure will not create a hazardous 
condition.
    (3) Failure of any flight or other mechanical control systems 
cables or systems components will not damage the EWIS and create a 
hazardous condition.
    (j) EWIS must be designed and installed with adequate physical

[[Page 58555]]

separation between the EWIS components and heated equipment, hot air 
ducts, and lines, so that:
    (1) Any EWIS component failure will not create a hazardous 
condition.
    (2) Any hot air leakage or heat generated onto EWIS components will 
not create a hazardous condition.
    (k) For systems for which redundancy is required, by certification 
rules, by operating rules, or as a result of the assessment required by 
Sec.  25.1705, EWIS components associated with those systems must be 
designed and installed with adequate physical separation.
    (l) Each EWIS must be designed and installed so there is adequate 
physical separation between it and aircraft structure, and so that the 
EWIS is protected from sharp edges and corners, to minimize potential 
for abrasion/chafing, vibration damage, and other types of mechanical 
damage.


Sec.  25.1711  Component identification: EWIS.

    (a) EWIS components must be labeled or otherwise identified using a 
consistent method that facilitates identification of the wire, its 
function, and its design limitations, if any.
    (b) For systems for which redundancy is required, by certification 
rules, by operating rules, or as a result of the assessment required by 
Sec.  25.1705, , EWIS components associated with those systems must be 
specifically identified with component part number, function, and 
separation requirement for bundles.
    (1) The identification must be placed along the wire, cable, or 
wire bundle at appropriate intervals and in areas of the airplane where 
it is readily visible to maintenance, repair, or alteration personnel.
    (2) If an EWIS component cannot be marked physically, then other 
means of identification must be provided.
    (c) The identifying markings required by paragraphs (a) and (b) of 
this section must remain legible throughout the expected service life 
of the EWIS component.
    (d) The means used for identifying each EWIS component as required 
by this section must not have an adverse effect on the performance of 
that component throughout its expected service life.
    (e) Identification for EWIS modifications to the type design must 
be consistent with the identification scheme of the original type 
design.


Sec.  25.1713  Fire protection: EWIS.

    (a) All EWIS components must meet the applicable fire and smoke 
protection requirements of Sec.  25.831(c) of this part.
    (b) EWIS components that are located in designated fire zones and 
are used during emergency procedures must be at least fire resistant.
    (c) Insulation on electrical wire and electrical cable, and 
materials used to provide additional protection for the wire and cable, 
installed in any area of the airplane, must be self-extinguishing when 
tested in accordance with the applicable portions of Appendix F, part 
I, of 14 CFR part 25.


Sec.  25.1715  [Reserved]


Sec.  25.1717  Electrical bonding and protection against static 
electricity: EWIS.

    (a) EWIS components used for electrical bonding and protection 
against static electricity must meet the requirements of Sec.  25.899.
    (b) Electrical bonding provided by EWIS components must provide an 
adequate electrical return path under both normal and fault conditions, 
on airplanes having grounded electrical systems.


Sec.  25.1719  Systems and functions: EWIS.

    (a) EWIS associated with systems required for type certification or 
by operating rules must be considered an integral part of that system 
and must be considered in showing compliance with the applicable 
requirements for that system.
    (b) For systems to which the following rules apply, the components 
of EWIS associated with those systems must be considered an integral 
part of that system or systems and must be considered in showing 
compliance with the applicable requirements for that system.
    (1) Sec.  25.773(b)(2) Pilot compartment view.
    (2) Sec.  25.981 Fuel tank ignition prevention.
    (3) Sec.  25.1165 Engine ignition systems.
    (4) Sec.  25.1310 Power source capacity and distribution.
    (5) Sec.  25.1316 System lightning protection.
    (6) Sec.  25.1351 General.
    (7) Sec.  25.1355 Distribution system.
    (8) Sec.  25.1360 Precautions against injury.
    (9) Sec.  25.1362 Electrical supplies for emergency conditions.
    (10) Sec.  25.1365 Electrical appliances, motors, and transformers.
    (11) Sec.  25.1431(c) and (d) Electronic equipment.


Sec.  25.1721  Circuit protective devices: EWIS.

    Electrical wires and cables must be designed and installed so they 
are compatible with the circuit protection devices required by Sec.  
25.1357, so that a fire or smoke hazard cannot be created under 
temporary or continuous fault conditions.


Sec.  25.1723  Instruments using a power supply: EWIS.

    EWIS components associated with any instrument required by Sec.  
25.1303(b) that uses a power supply must be designed and installed so 
that failure of the EWIS components would not affect that instrument's 
compliance with Sec.  25.1331(a)(2).


Sec.  25.1725  Accessibility provisions: EWIS.

    Access must be provided to allow inspection and replacement of any 
EWIS component as necessary for continued airworthiness.


Sec.  25.1727  Protection of EWIS.

    (a) No cargo or baggage compartment may contain any EWIS whose 
damage or failure may affect safe operation, unless the EWIS is 
protected so that:
    (1) It cannot be damaged by movement of cargo or baggage in the 
compartment.
    (2) Its breakage or failure will not create a fire hazard.
    (b) EWIS must be designed and installed to minimize damage and risk 
of damage to EWIS by movement of people in the airplane during all 
phases of flight, maintenance, and servicing.
    (c) EWIS must be designed and installed to minimize damage and risk 
of damage to EWIS by items carried onto the aircraft by passengers or 
cabin crew.


Sec.  25.1729  Flammable fluid fire protection: EWIS.

    EWIS components located in each area where flammable fluid or 
vapors might escape by leakage of a fluid system must be considered to 
be a potential ignition source and must meet the requirements of Sec.  
25.863.


Sec.  25.1731  Powerplants: EWIS.

    (a) EWIS associated with any powerplant must be designed and 
installed so that the failure of an EWIS component will not prevent the 
continued safe operation of the remaining powerplants or require 
immediate action by any crewmember for continued safe operation, in 
accordance with the requirements of Sec.  25.903(b).
    (b) Design precautions must be taken to minimize hazards to the 
airplane due to EWIS damage in the event of a powerplant rotor failure 
or a fire originating within the powerplant that burns through the 
powerplant case, in accordance with the requirements of Sec.  
25.903(d)(1).


Sec.  25.1733  Flammable fluid shutoff means: EWIS.

    EWIS associated with each flammable fluid shutoff means and control 
must be fireproof or must be located and

[[Page 58556]]

protected so that any fire in a fire zone will not affect operation of 
the flammable fluid shutoff means, in accordance with the requirements 
of Sec.  25.1189.


Sec.  25.1735  Fire detector systems, general: EWIS.

    EWIS associated with any installed fire protection system must be 
considered an integral part of the system in showing compliance with 
the applicable requirements for that system.


Sec.  25.1737  Powerplant and APU fire detector system: EWIS.

    (a) EWIS that are part of each fire or overheat detector system in 
a fire zone must be at least fire-resistant.
    (b) No EWIS component of any fire or overheat detector system for 
any fire zone may pass through another fire zone, unless:
    (1) It is protected against the possibility of false warnings 
resulting from fires in zones through which it passes; or
    (2) Each zone involved is simultaneously protected by the same 
detector and extinguishing system.
    (c) EWIS that are part of each fire or overheat detector system in 
a fire zone must meet the requirements of Sec.  25.1203.


Sec.  25.1739  Instructions for Continued Airworthiness: EWIS.

    The applicant must prepare Instructions for Continued Airworthiness 
applicable to EWIS in accordance with Appendix H sections H25.4 and 
H25.5 to this part that are approved by the FAA.
    20. Amend part 25 by adding new subpart I to read as follows.
Subpart I--Continued Airworthiness and Safety Improvements
Sec.
25.1801 Purpose and definition.
25.1803 [Reserved]
25.1805 Electrical wiring interconnection systems (EWIS) maintenance 
program.

Subpart I--Continued Airworthiness and Safety Improvements


Sec.  25.1801  Purpose and definition.

    (a) This subpart establishes requirements for support of the 
continued airworthiness of transport category airplanes. These 
requirements may include performing assessments, developing design 
changes, developing revisions to Instructions for Continued 
Airworthiness, and making necessary documentation available to affected 
persons. This subpart applies to the following persons, as specified in 
each section of this subpart:
    (1) Holders of type certificates.
    (2) Applicants for type certificates and changes to type 
certificates (including service bulletins describing design changes). 
Applicants for changes to type certificates must comply with the 
requirements of this subpart in addition to the airworthiness 
requirements determined applicable under Sec.  21.101 of this 
subchapter.
    (b) For purposes of this subpart, the ``FAA Oversight Office'' is 
the aircraft certification office or office of the Transport Airplane 
Directorate with oversight responsibility for the relevant type 
certificate or supplemental type certificate, as determined by the 
Administrator.


Sec.  25.1803  [Reserved]


Sec.  25.1805  Electrical wiring interconnection systems (EWIS) 
maintenance program.

    (a) Except as provided in paragraph (f) of this section, this 
section applies to transport category, turbine-powered airplanes with a 
type certificate issued after January 1, 1958, that, as a result of the 
original certification, or later increase in capacity, have--
    (1) A maximum type-certificated passenger capacity of 30 or more or
    (2) A maximum payload capacity of 7,500 pounds or more.
    (b) Each person identified in paragraph (c) of this section must 
develop and submit for review and approval by the FAA Oversight Office 
Instructions for Continued Airworthiness for the representative 
airplane's EWIS in accordance with Appendix H paragraphs H25.5(a)(1) 
and (b) of this part in effect on [effective date of final rule] for 
each affected type design. For purposes of this section, the 
``representative airplane'' is the configuration of each model series 
airplane that incorporates all variations of EWIS used on that series 
airplane, and that includes all TC-holder-designed modifications 
mandated by airworthiness directive as of the effective date of this 
rule. Each person specified in paragraph (c) of this section must also 
review any fuel tank system Instructions for Continued Airworthiness 
developed by that person to comply with SFAR 88 to ensure compatibility 
with the EWIS Instructions for Continued Airworthiness, including 
minimizing redundant requirements.
    (c) The following persons must comply with the requirements of 
paragraph (b) of this section before the dates specified.
    (1) Holders of type certificates (TC): December 16, 2007.
    (2) Applicants for TCs, and amendments to TCs (including service 
bulletins describing design changes), if the date of application was 
before [effective date of final rule] and the certificate was issued on 
or after [effective date of final rule]: December 16, 2007, or the date 
the certificate is issued, whichever occurs later.
    (3) Unless compliance with Sec.  25.1739 of this part is required 
or elected, applicants for amendments to TCs, if the application was 
filed after [effective date of final rule]: December 16, 2007, or the 
date of approval of the application, whichever occurs later.
    (4) Applicants for supplemental type certificates (STC), if the 
date of application was before [effective date of final rule] and the 
certificate was issued on or after [effective date of final rule]: June 
16, 2008, or the date of approval of the application, whichever occurs 
later.
    (5) Unless compliance with Sec.  25.1739 of this part is required 
or elected, applicants for STCs, if the application was filed after 
[effective date of final rule]: June 16, 2008, or the date of approval 
of the application, whichever occurs later.
    (d) Each person identified in paragraphs (c)(1), (c)(2), and (c)(4) 
of this section must submit to the FAA Oversight Office for approval a 
compliance plan by [insert date 90 days after effective date of final 
rule]. The compliance plan must include the following information:
    (1) A proposed project schedule, identifying all major milestones, 
for meeting the compliance dates specified in paragraph (c) of this 
section.
    (2) A proposed means of compliance with this section, identifying 
all required submissions, including all compliance items as mandated in 
Appendix H paragraphs H25.5(a)(1) and (b) of this part in effect on 
[effective date of this final rule], and all data to be developed to 
substantiate compliance.
    (3) If the affected person proposes a means of compliance that 
differs from that described in FAA advisory material, a detailed 
explanation of how the proposed means will be shown to comply with this 
section.
    (4) A proposal for submitting a draft of all compliance items 
required by paragraph (d)(2) of this section for review by the FAA 
Oversight Office not less than 60 days before the compliance time 
specified in paragraph (c) of this section.
    (5) A proposal for how the approved Instructions for Continued 
Airworthiness will be made available to affected persons.
    (e) Each affected person must implement the compliance plan as 
approved in compliance with paragraph

[[Page 58557]]

(d) of this section. If either paragraph (e)(1) or (2) of this section 
applies, the affected person must submit a corrected plan to the FAA 
Oversight Office and implement the corrected plan within 30 days after 
such notification.
    (1) The FAA Oversight Office notifies the affected person of 
deficiencies in the proposed compliance plan and how to correct them.
    (2) The FAA Oversight Office notifies the affected person of 
deficiencies in the person's implementation of the plan and how to 
correct them.
    (f) This section does not apply to the following airplane models:
    (1) Convair CV-240, 340, 440, if modified to include turbine 
engines.
    (2) Lockheed L-188
    (3) Vickers Armstrong Viscount
    (4) Douglas DC-3, if modified to include turbine engines
    (5) Bombardier CL-44
    (6) Mitsubishi YS-11
    (7) British Aerospace BAC 1-11
    (8) Concorde
    (9) deHavilland D.H. 106 Comet 4C
    (10) VFW-Vereinigte Flugtechnische Werk VFW-614
    (11) Illyushin Aviation IL 96T
    (12) Bristol Aircraft Britannia 305
    (13) Handley Page Herald Type 300
    (14) Avions Marcel Dassault--Breguet Aviation Mercure 100C
    (15) Airbus Caravelle

APPENDIX H TO PART 25--INSTRUCTIONS FOR CONTINUED AIRWORTHINESS

    21. Amend H25.1 by revising paragraph (a) to read as follows:

H25.1 General.

    (a) This appendix specifies requirements for preparation of 
Instructions for Continued Airworthiness as required by Sec. Sec.  
25.1529, 25.1739, and applicable provisions of subpart I of this 
part.
* * * * *

    22. Amend H25.4 by revising paragraph (a)(1) and adding new 
paragraph (a)(3) to read as follows:

H25.4 Airworthiness Limitations section.

    (a) * * *
    (1) Each mandatory replacement time, structural inspection 
interval, and related structural inspection procedures approved 
under Sec.  25.571.
    (2) * * *
    (3) Any mandatory replacement time of EWIS components as defined 
in section 25.1701.
* * * * *

    23. Amend Appendix H to part 25 by adding new paragraph H25.5 to 
read as follows:
H25.5 Electrical Wiring Interconnection System (EWIS) Instructions for 
Continued Airworthiness.

    (a) The applicant must prepare Instructions for Continued 
Airworthiness applicable to EWIS as defined by Sec.  25.1701 that 
are approved by the FAA and include the following:
    (1) Maintenance and inspection requirements for the EWIS 
developed with the use of an enhanced zonal analysis procedure that 
includes:
    (i) Identification of each zone of the airplane.
    (ii) Identification of each zone that contains EWIS.
    (iii) Identification of each zone containing EWIS that also 
contains combustible materials.
    (iv) Identification of each zone in which EWIS is in close 
proximity to both primary and back-up hydraulic, mechanical, or 
electrical flight controls and lines.
    (v) Identification of--
    (A) Tasks, and the intervals for performing those tasks, that 
will reduce the likelihood of ignition sources and accumulation of 
combustible material, and
    (B) Procedures, and the intervals for performing those 
procedures, that will effectively clean the EWIS components of 
combustible material if there is not an effective task to reduce the 
likelihood of combustible material accumulation.
    (vi) Instructions for protections and caution information that 
will minimize contamination and accidental damage to EWIS, as 
applicable, during performance of maintenance, alteration, or 
repairs.
    (2) Acceptable EWIS maintenance practices in a standard format.
    (3) Wire separation requirements as determined under Sec.  
25.1709.
    (4) Information explaining the EWIS identification method and 
requirements for identifying any changes to EWIS under Sec.  
25.1711.
    (5) Electrical load data and instructions for updating that 
data.
    (b) The Instructions for Continued Airworthiness must be in the 
form of a document appropriate for the information to be provided, 
and they must be easily recognizable as EWIS Instructions for 
Continued Airworthiness.

PART 91--GENERAL OPERATING AND FLIGHT RULES

    24. The authority for part 91 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 1155, 40103, 40113, 40120, 44101, 
44111, 44701, 44709, 44711, 44712, 44715, 44716, 44717, 44722, 
46306, 46315, 46316, 46504, 46506-46507, 47122, 47508, 47528-47531, 
articles 12 and 29 of the Convention on International Civil Aviation 
(61 stat. 1180).

    25. Amend part 91 by adding new Subpart L as follows:
Subpart L--Continued Airworthiness and Safety Improvements
Sec.
91.1501 Purpose and definition.
91.1503 [Reserved]
91.1505 [Reserved]
91.1507 Fuel tank system maintenance program.

Subpart L--Continued Airworthiness and Safety Improvements


Sec.  91.1501  Purpose and definition.

    (a) This subpart requires operators to support the continued 
airworthiness of each airplane. These requirements may include, but are 
not limited to, revising the inspection program, incorporating design 
changes, and incorporating revisions to Instructions for Continued 
Airworthiness.
    (b) For purposes of this subpart, the ``FAA Oversight Office'' is 
the aircraft certification office or office of the Transport Airplane 
Directorate with oversight responsibility for the relevant type 
certificate or supplemental type certificate, as determined by the 
Administrator.


Sec.  91.1503  [Reserved]


Sec.  91.1505  [Reserved]


Sec.  91.1507  Fuel tank system maintenance program.

    (a) Except as provided in paragraph (g) of this section, this 
section applies to transport category, turbine-powered airplanes with a 
type certificate issued after January 1, 1958, that, as a result of 
original type certification or later increase in capacity, have--
    (1) A maximum type-certificated passenger capacity of 30 or more, 
or
    (2) A maximum payload capacity of 7,500 pounds or more.
    (b) For each airplane on which an auxiliary fuel tank is installed 
under a field approval, before December 16, 2007, the operator must 
submit to the FAA Oversight Office proposed maintenance instructions 
for the tank that meet the requirements of Special Federal Aviation 
Regulation No. 88 (SFAR 88) of this chapter.
    (c) After December 16, 2008, no operator may operate an airplane 
identified in paragraph (a) of this section unless the inspection 
program for that airplane has been revised to include inspections, 
procedures, and limitations for fuel tank systems.
    (d) The proposed fuel tank system inspection program revisions must 
be based on the following documents:
    (1) The applicable type-certificate-holder-developed fuel tank 
Instructions for Continued Airworthiness, developed under SFAR 88, or 
under Sec.  25.1529 in

[[Page 58558]]

effect on June 6, 2001, approved by the FAA Oversight Office.
    (2) The applicable supplemental-type-certificate-holder-developed 
fuel tank Instructions for Continued Airworthiness, if any, developed 
under SFAR 88, or Instructions for Continued Airworthiness developed in 
accordance with Sec.  25.1529 in effect on June 6, 2001, approved by 
the FAA Oversight Office.
    (3) The applicable operator-developed inspection instructions for 
field-approved auxiliary fuel tanks, if any, approved by the FAA 
Oversight Office for the type certificate.
    (e) After December 16, 2008, before returning an airplane to 
service after any alterations for which fuel tank Instructions for 
Continued Airworthiness are developed under SFAR 88, or under Sec.  
25.1529 in effect on June 6, 2001, the operator must include in the 
inspection program for the airplane inspections and procedures for the 
fuel tank system based on those Instructions for Continued 
Airworthiness.
    (f) The fuel tank system inspection program changes identified in 
paragraphs (d) and (e) of this section and any later fuel tank system 
revisions must be submitted to the cognizant Flight Standards District 
Office (FSDO) for review and approval.
    (g) This section does not apply to the following airplane models:
    (1) Convair CV-240, 340, 440, if modified to include turbine 
engines.
    (2) Lockheed L-188
    (3) Vickers Armstrong Viscount
    (4) Douglas DC-3, if modified to include turbine engines
    (5) Bombardier CL-44
    (6) Mitsubishi YS-11
    (7) British Aerospace BAC 1-11
    (8) Concorde
    (9) deHavilland D.H. 106 Comet 4C
    (10) VFW-Vereinigte Flugtechnische Werk VFW-614
    (11) Illyushin Aviation IL 96T
    (12) Bristol Aircraft Britannia 305
    (13) Handley Page Herald Type 300
    (14) Avions Marcel Dassault--Breguet Aviation Mercure 100C
    (15) Airbus Caravelle
    26. Designate the text of current Sec.  91.410 as new Sec.  
91.1505, removing and reserving paragraph (b), and revising the section 
heading to read as follows:


Sec.  91.1505  Repairs assessment for pressurized fuselages.


Sec.  91.410  [Reserved]

    27. Sec.  91.410 is reserved.

PART 121--OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL 
OPERATIONS

    28. The authority citation for part 121 continues to read:

    Authority: 49 U.S.C. 106(g), 40113, 40119, 41706, 44101, 44701-
44702, 44705, 44709-44711, 44713, 44716-44717, 44722, 44901, 44903-
44904, 44912, 45101-45105, 46105, 46301.

    29. Amend part 121 by adding new subpart Y to read as follows:
Subpart Y--Continued Airworthiness and Safety Improvements
Sec.
121.901 Purpose and definition.
121.903 [Reserved]
121.905 [Reserved]
121.907 [Reserved]
121.909 [Reserved]
121.911 Electrical wiring interconnection systems (EWIS) maintenance 
program.
121.913 Fuel tank system maintenance program.

Subpart Y--Continued Airworthiness and Safety Improvements


Sec.  121.901  Purpose and definition.

    (a) This subpart requires persons holding an air carrier or 
operating certificate under part 119 of this chapter to support the 
continued airworthiness of each airplane. These requirements may 
include, but are not limited to, revising the maintenance program, 
incorporating design changes, and incorporating revisions to 
Instructions for Continued Airworthiness.
    (b) For purposes of this subpart, the ``FAA Oversight Office'' is 
the aircraft certification office or office of the Transport Airplane 
Directorate with oversight responsibility for the relevant type 
certificate or supplemental type certificate, as determined by the 
Administrator.


Sec.  121.903  [Reserved]


Sec.  121.905  [Reserved]


Sec.  121.907  [Reserved]


Sec.  121.909  [Reserved]


Sec.  121.911  Electrical wiring interconnection systems (EWIS) 
maintenance program.

    (a) Except as provided in paragraph (f) of this section, this 
section applies to transport category, turbine-powered airplanes with a 
type certificate issued after January 1, 1958, that, as a result of 
original type certification or later increase in capacity, have--
    (1) A maximum type-certificated passenger capacity of 30 or more, 
or
    (2) A maximum payload capacity of 7500 pounds or more.
    (b) After December 16, 2008, no certificate holder may operate an 
airplane identified in paragraph (a) of this section unless the 
maintenance program for that airplane includes inspections and 
procedures for electrical wiring interconnection systems (EWIS).
    (c) The proposed EWIS maintenance program changes must be based on 
the following documents:
    (1) The applicable EWIS Instructions for Continued Airworthiness, 
developed by the type certificate holder and approved by the FAA 
Oversight Office.
    (2) The applicable EWIS Instructions for Continued Airworthiness, 
if any, developed for supplemental type certificates, approved by the 
FAA Oversight Office.
    (d) After December 16, 2008, before returning an airplane to 
service after any alterations for which EWIS Instructions for Continued 
Airworthiness are developed, the certificate holder must include in the 
airplane's maintenance program inspections and procedures for EWIS 
based on those Instructions for Continued Airworthiness.
    (e) The EWIS maintenance program changes identified in paragraphs 
(c) and (d) of this section and any later EWIS revisions must be 
submitted to the Principal Inspector for review and approval.
    (f) This section does not apply to the following airplane models:
    (1) Convair CV-240, 340, 440, if modified to include turbine 
engines.
    (2) Lockheed L-188
    (3) Vickers Armstrong Viscount
    (4) Douglas DC-3, if modified to include turbine engines
    (5) Bombardier CL-44
    (6) Mitsubishi YS-11
    (7) British Aerospace BAC 1-11
    (8) Concorde
    (9) deHavilland D.H. 106 Comet 4C
    (10) VFW-Vereinigte Flugtechnische Werk VFW-614
    (11) Illyushin Aviation IL 96T
    (12) Bristol Aircraft Britannia 305
    (13) Handley Page Herald Type 300
    (14) Avions Marcel Dassault--Breguet Aviation Mercure 100C
    (15) Airbus Caravelle


Sec.  121.913  Fuel tank system maintenance program.

    (a) Except as provided in paragraph (g) of this section, this 
section applies to transport category, turbine-powered airplanes with a 
type certificate issued after January 1, 1958, that, as a result of 
original type certification or later increase in capacity, have--
    (1) A maximum type-certificated passenger capacity of 30 or more, 
or
    (2) A maximum payload capacity of 7500 pounds or more.
    (b) For each airplane on which an auxiliary fuel tank is installed 
under a

[[Page 58559]]

field approval, before December 16, 2007, the certificate holder must 
submit to the FAA Oversight Office proposed maintenance instructions 
for the tank that meet the requirements of Special Federal Aviation 
Regulation No. 88 (SFAR 88) of this chapter.
    (c) After December 16, 2008, no certificate holder may operate an 
airplane identified in paragraph (a) of this section unless the 
maintenance program for that airplane has been revised to include 
inspections, procedures, and limitations for fuel tanks systems.
    (d) The proposed fuel tank system maintenance program revisions 
must be based on the following documents:
    (1) The applicable type-certificate-holder-developed fuel tank 
Instructions for Continued Airworthiness, developed under SFAR 88 or 
under Sec.  25.1529 in effect on June 6, 2001, approved by the FAA 
Oversight Office.
    (2) The applicable supplemental-type-certificate-holder-developed 
fuel tank Instructions for Continued Airworthiness, if any, developed 
under SFAR 88, or under Sec.  25.1529 in effect on June 6, 2001, 
approved by the FAA Oversight Office.
    (3) The applicable certificate-holder-developed maintenance 
instructions for field-approved auxiliary fuel tanks, if any, approved 
by the FAA Oversight Office for the type certificate.
    (e) After December 16, 2008, before returning an aircraft to 
service after any alteration for which fuel tank Instructions for 
Continued Airworthiness are developed under SFAR 88 or under Sec.  
25.1529 in effect on June 6, 2001, the certificate holder must include 
in the maintenance program for the airplane inspections and procedures 
for the fuel tank system based on those Instructions for Continued 
Airworthiness.
    (f) The fuel tank system program changes identified in paragraphs 
(d) and (e) of this section and any later fuel tank system revisions 
must be submitted to the Principal Inspector for review and approval.
    (g) This section does not apply to the following airplane models:
    (1) Convair CV-240, 340, 440, if modified to include turbine 
engines.
    (2) Lockheed L-188
    (3) Vickers Armstrong Viscount
    (4) Douglas DC-3, if modified to include turbine engines
    (5) Bombardier CL-44
    (6) Mitsubishi YS-11
    (7) British Aerospace BAC 1-11
    (8) Concorde
    (9) deHavilland D.H. 106 Comet 4C
    (10) VFW-Vereinigte Flugtechnische Werk VFW-614
    (11) Illyushin Aviation IL 96T
    (12) Bristol Aircraft Britannia 305
    (13) Handley Page Herald Type 300
    (14) Avions Marcel Dassault--Breguet Aviation Mercure 100C
    (15) Airbus Caravelle


Sec.  121.368  [Redesignated as Sec.  121.905]

    30. Redesignate Sec.  121.368 as new Sec.  121.905 and reserve 
Sec. 121.368.


Sec.  121.368  [Reserved]

    31. Sec.  121.368 is reserved.
    32. Designate the text of current Sec.  121.370 as new Sec.  
121.907, removing and reserving paragraph (b), and revising the section 
heading to read as follows:


Sec.  121.907  Repairs assessment for pressurized fuselages.


Sec.  121.370  [Reserved]

    33. Sec.  121.370 is reserved.


Sec.  121.370a  [Redesignated as Sec. 121.909]

    34. Redesignate Sec.  121.370a as new Sec. 121.909 and reserve 
Sec.  121.370a.


Sec.  121.370a  [Reserved]

    35. Sec.  121.370a is reserved.

PART 125--CERTIFICATION AND OPERATIONS: AIRPLANES HAVING A SEATING 
CAPACITY OF 20 OR MORE PASSENGERS OR A MAXIMUM PAYLOAD CAPACITY OF 
6,000 POUNDS OR MORE; AND RULES GOVERNING PERSONS ON BOARD SUCH 
AIRCRAFT

    36. The authority citation for part 125 continues to read:

    Authority: 49 U.S.C. 106(g), 40113, 44701-44702, 44705, 44710-
44711, 44713, 44716-44717, 44722.

    37. Amend part 125 by adding new subpart M to read as follows:
Subpart M--Continued Airworthiness and Safety Improvements
Sec.
125.501 Purpose and definition.
125.503 [Reserved]
125.505 [Reserved]
125.507 Fuel tank system inspection program.

Subpart M--Continued Airworthiness and Safety Improvements


Sec.  125.501  Purpose and definition.

    (a) This subpart requires operators to support the continued 
airworthiness of each airplane. These requirements may include, but are 
not limited to, revising the inspection program, incorporating design 
changes, and incorporating revisions to Instructions for Continued 
Airworthiness.
    (b) For purposes of this subpart, the ``FAA Oversight Office'' is 
the aircraft certification office or office of the Transport Airplane 
Directorate with oversight responsibility for the relevant type 
certificate or supplemental type certificate, as determined by the 
Administrator.


Sec.  125.503  [Reserved]


Sec.  125.505  [Reserved]


Sec.  125.507  Fuel tank system inspection program.

    (a) Except as provided in paragraph (g) of this section, this 
section applies to transport category, turbine-powered airplanes with a 
type certificate issued after January 1, 1958, that, as a result of 
original type certification or later increase in capacity, have--
    (1) a maximum type-certificated passenger capacity of 30 or more, 
or
    (2) a maximum payload capacity of 7500 pounds or more.
    (b) For each airplane on which an auxiliary fuel tank is installed 
under a field approval, before December 16, 2007, the certificate 
holder must submit to the FAA Oversight Office proposed maintenance 
instructions for the tank that meet the requirements of Special Federal 
Aviation Regulation No. 88 (SFAR 88) of this chapter.
    (c) After December 16, 2008, no certificate holder may operate an 
airplane identified in paragraph (a) of this section unless the 
inspection program for that airplane has been revised to include 
inspections, procedures, and limitations for fuel tank systems.
    (d) The proposed fuel tank system inspection program revisions must 
be based on the following documents:
    (1) The applicable type-certificate-holder-developed fuel tank 
Instructions for Continued Airworthiness, developed under SFAR 88, or 
under Sec.  25.1529 in effect on June 6, 2001, approved by the FAA 
Oversight Office.
    (2) The applicable supplemental-type-certificate-holder-developed 
fuel tank Instructions for Continued Airworthiness, if any, developed 
under SFAR 88, or under Sec.  25.1529 in effect on June 6, 2001, 
approved by the FAA Oversight Office.
    (3) The applicable certificate-holder-developed inspection 
instructions for field-approved auxiliary fuel tanks, if any, approved 
by the FAA Oversight Office for the type certificate.
    (e) After December 16, 2008, before returning an aircraft to 
service after any alteration for which fuel tank Instructions for 
Continued Airworthiness are developed under SFAR 88, or under Sec.  
25.1529 in effect on June 6, 2001, the certificate holder must include 
in the inspection program for

[[Page 58560]]

the airplane inspections and procedures for the fuel tank system based 
on those Instructions for Continued Airworthiness.
    (f) The fuel tank system program changes identified in paragraphs 
(d) and (e) of this section and any later fuel tank system revisions 
must be submitted to the Principal Inspector for review and approval.
    (g) This section does not apply to the following airplane models:
    (1) Convair CV-240, 340, 440, if modified to include turbine 
engines.
    (2) Lockheed L-188
    (3) Vickers Armstrong Viscount
    (4) Douglas DC-3, if modified to include turbine engines
    (5) Bombardier CL-44
    (6) Mitsubishi YS-11
    (7) British Aerospace BAC 1-11
    (8) Concorde
    (9) deHavilland D.H. 106 Comet 4C
    (10) VFW-Vereinigte Flugtechnische Werk VFW-614
    (11) Illyushin Aviation IL 96T
    (12) Bristol Aircraft Britannia 305
    (13) Handley Page Herald Type 300
    (14) Avions Marcel Dassault--Breguet Aviation Mercure 100C
    (15) Airbus Caravelle
    38. Designate the text of current Sec.  125.248 as new Sec.  
125.505, removing and reserving paragraph (b), and revising the section 
heading to read as follows:


Sec.  125.505  Repairs assessment for pressurized fuselages.


Sec.  125.248  [Reserved]

    39. Sec.  125.248 is reserved.

PART 129--OPERATIONS: FOREIGN AIR CARRIERS AND FOREIGN OPERATORS OF 
U.S.-REGISTERED AIRCRAFT ENGAGED IN COMMON CARRIAGE

    40. The authority citation for part 129 continues to read:

    Authority: 49 U.S.C. 1372, 40113, 40119, 44101, 44701-44702, 
44705, 44709-44711, 44713, 44716-44717, 44722, 44901-44904, 44906, 
44912, 46105, Pub. L. 107-71 sec. 104.

    41. Amend part 129 by:
    A. Designating the existing sections, except Sec. Sec.  129.16, 
129.32, and 129.33, as ``Subpart A--General'';
    B. Revising paragraph (b) of Sec.  129.1;
    C. Redesignating Sec. Sec.  129.16, 129.32, and 129.33 as 
Sec. Sec.  129.109, 129.107, and 129.105, respectively, and revising 
the heading for newly designated Sec.  129.107 and removing and 
reserving paragraph (b); and
    D. Adding a new subpart B.
    The revisions and additions read as follows:

Subpart A--General


Sec.  129.1  Applicability and definitions.

* * * * *
    (b) Operations of U.S.-registered aircraft solely outside the 
United States. In addition to the operations specified under paragraph 
(a) of this section, Sec. Sec.  129.14 and 129.20 and subpart B of this 
part also apply to U.S.-registered aircraft operated solely outside the 
United States in common carriage by a foreign person or foreign air 
carrier.
* * * * *
Subpart B--Continued Airworthiness and Safety Improvements
Sec.
129.101 Purpose and definition.
129.103 [Reserved]
129.105 Aging airplane inspections and records reviews for U.S.-
registered multiengine aircraft.
129.107 Repairs assessment for pressurized fuselages.
129.109 Supplemental inspections for U.S.-registered aircraft.
129.111 Electrical wiring interconnection systems (EWIS) maintenance 
program.
129.113 Fuel tank system maintenance program.

Subpart B--Continued Airworthiness and Safety Improvements


Sec.  129.101  Purpose and definition.

    (a) This subpart requires a foreign person or foreign air carrier 
operating a U.S. registered airplane in common carriage to support the 
continued airworthiness of each airplane. These requirements may 
include, but are not limited to, revising the maintenance program, 
incorporating design changes, and incorporating revisions to 
Instructions for Continued Airworthiness.
    (b) For purposes of this subpart, the ``FAA Oversight Office'' is 
the aircraft certification office or office of the Transport Airplane 
Directorate with oversight responsibility for the relevant type 
certificate or supplemental type certificate, as determined by the 
Administrator.


Sec.  129.103  [Reserved]


Sec.  129.105  [Redesignated from Sec.  129.33]


Sec.  129.107  [Redesignated from Sec.  129.32]


Sec.  129.109  [Redesignated from Sec. 129.16]


Sec.  129.111  Electrical wiring interconnection systems (EWIS) 
maintenance program.

    (a) Except as provided in paragraph (f) of this section, this 
section applies to transport category, turbine-powered airplanes with a 
type certificate issued after January 1, 1958, that, as a result of 
original type certification or later increase in capacity, have--
    (1) A maximum type-certificated passenger capacity of 30 or more, 
or
    (2) A maximum payload capacity of 7500 pounds or more.
    (b) After December 16, 2008, no foreign person or foreign air 
carrier may operate an airplane identified in paragraph (a) of this 
section unless the maintenance program for that airplane includes 
inspections and procedures for EWIS.
    (c) The proposed EWIS maintenance program changes must be based on 
the following documents:
    (1) The applicable EWIS Instructions for Continued Airworthiness, 
developed by the type certificate holder and approved by the FAA 
Oversight Office.
    (2) The applicable EWIS Instructions for Continued Airworthiness, 
if any, developed for supplemental type certificates, approved by the 
FAA Oversight Office.
    (d) After December 16, 2008, before returning an airplane to 
service after any alterations for which EWIS Instructions for Continued 
Airworthiness are developed, the foreign person or foreign air carrier 
must include in the maintenance program for that airplane inspections 
and procedures for EWIS based on those Instructions for Continued 
Airworthiness.
    (e) The EWIS maintenance program changes identified in paragraphs 
(c) and (d) of this section and any later EWIS revisions must be 
submitted to the Principal Inspector or cognizant Flight Standards 
International Field Office for review and approval.
    (f) This section does not apply to the following airplane models:
    (1) Convair CV-240, 340, 440, if modified to include turbine 
engines.
    (2) Lockheed L-188
    (3) Vickers Armstrong Viscount
    (4) Douglas DC-3, if modified to include turbine engines
    (5) Bombardier CL-44
    (6) Mitsubishi YS-11
    (7) British Aerospace BAC 1-11
    (8) Concorde
    (9) deHavilland D.H. 106 Comet 4C
    (10) VFW-Vereinigte Flugtechnische Werk VFW-614
    (11) Illyushin Aviation IL 96T
    (12) Bristol Aircraft Britannia 305
    (13) Handley Page Herald Type 300
    (14) Avions Marcel Dassault-Breguet Aviation Mercure 100C
    (15) Airbus Caravelle


Sec.  129.113  Fuel tank system maintenance program.

    (a) Except as provided in paragraph (g) of this section, this 
section applies to transport category, turbine-powered airplanes with a 
type certificate issued after January 1, 1958, that, as a result of

[[Page 58561]]

original type certification or later increase in capacity, have--
    (1) A maximum type-certificated passenger capacity of 30 or more, 
or
    (2) A maximum payload capacity of 7500 pounds or more.
    (b): For each airplane on which an auxiliary fuel tank is installed 
under a field approval, before December 16, 2007, the foreign person or 
foreign air carrier operating the airplane must submit to the FAA 
Oversight Office proposed maintenance instructions for the tank that 
meet the requirements of Special Federal Aviation Regulation No. 88 
(SFAR 88) of this chapter.
    (c) After December 16, 2008, no foreign person or foreign air 
carrier may operate an airplane identified in paragraph (a) of this 
section unless the maintenance program for that airplane has been 
revised to include inspections, procedures, and limitations for fuel 
tanks systems.
    (d) The proposed fuel tank system maintenance program revisions 
must be based on the following documents:
    (1) The applicable type-certificate-holder-developed fuel tank 
Instructions for Continued Airworthiness, developed under SFAR 88, or 
under Sec.  25.1529 in effect on June 6, 2001, approved by the FAA 
Oversight Office.
    (2) The applicable supplemental-type-certificate-holder-developed 
fuel tank Instructions for Continued Airworthiness, if any, developed 
under SFAR 88, or Instructions for Continued Airworthiness developed in 
accordance with Sec.  25.1529 in effect on June 6, 2001, approved by 
the FAA Oversight Office.
    (3) The applicable maintenance instructions for field-approved 
auxiliary fuel tanks, if any, developed by the foreign person or 
foreign air carrier operating the airplane and approved by the FAA 
Oversight Office for the type certificate.
    (e) After December 16, 2008, before returning an airplane to 
service after any alteration for which fuel tank Instructions for 
Continued Airworthiness are developed under SFAR 88, or under Sec.  
25.1529 in effect on June 6, 2001, the foreign person or foreign air 
carrier must include in the maintenance program for the airplane 
inspections and procedures for the fuel tank system based on those 
Instructions for Continued Airworthiness.
    (f) The fuel tank system program changes identified in paragraphs 
(d) and (e) of this section and any later fuel tank system revisions 
must be submitted to the Principal Inspector or cognizant Flight 
Standards International Field Office for review and approval.
    (g) This section does not apply to the following airplane models:
    (1) Convair CV-240, 340, 440, if modified to include turbine 
engines.
    (2) Lockheed L-188
    (3) Vickers Armstrong Viscount
    (4) Douglas DC-3, if modified to include turbine engines
    (5) Bombardier CL-44
    (6) Mitsubishi YS-11
    (7) British Aerospace BAC 1-11
    (8) Concorde
    (9) deHavilland D.H. 106 Comet 4C
    (10) VFW-Vereinigte Flugtechnische Werk VFW-614
    (11) Illyushin Aviation IL 96T
    (12) Bristol Aircraft Britannia 305
    (13) Handley Page Herald Type 300
    (14) Avions Marcel Dassault--Breguet Aviation Mercure 100C
    (15) Airbus Caravelle

    Issued in Washington, DC on September 22, 2005.
James J. Ballough,
Director, Flight Standards Service.
John J. Hickey,
Director, Aircraft Certification Service.
[FR Doc. 05-19419 Filed 10-5-05; 8:45 am]
BILLING CODE 4910-13-P