[Federal Register Volume 72, Number 69 (Wednesday, April 11, 2007)]
[Proposed Rules]
[Pages 18148-18155]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-6535]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 33

[Docket No. FAA-2007-27311; Notice No. 07-03]
RIN 2120-AI94


Airworthiness Standards; Engine Control System Requirements

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The Federal Aviation Administration (FAA) is proposing to 
revise type certification standards for aircraft engine control 
systems. These proposed changes reflect current practices and harmonize 
FAA standards with those recently adopted by the European Aviation 
Safety Agency (EASA). These proposed changes would establish uniform 
standards for all engine control systems for aircraft engines 
certificated by both U.S. and European countries and would simplify 
airworthiness approvals for import and export.

DATES: Send your comments on or before July 10, 2007.

ADDRESSES: You may send comments identified by Docket Number [FAA-2007-
27311] 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.

[[Page 18149]]

     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 20590-0001.
     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: Gary Horan, Engine and Propeller 
Directorate Standards Staff, ANE-111, Federal Aviation Administration, 
12 New England Executive Park, Burlington, Massachusetts 01803-5299; 
telephone (781) 238-7164, fax (781) 238-7199, e-mail 
[email protected].

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 
concerning 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 sending 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.

Background

    U.S. and European aircraft engine regulations differ in several 
areas including engine controls. Harmonization of these differences 
benefits industry and regulators because of the lower costs associated 
with one set of engine control regulations.
    The FAA, in cooperation with the Joint Aviation Authorities (JAA), 
the European rulemaking authority before EASA, established an 
international engine certification study group to compare part 33 with 
the Joint Aviation Requirements--Engines (JAR-E), the European 
requirements for engines. As a follow-on, the Aviation Rulemaking 
Advisory Committee, through its Engine Harmonization Working Group 
(EHWG), looked at harmonizing the engine control requirements of part 
33 and the JAR-E.
    In response to EHWG recommendations, the JAA published a Notice of 
Proposed Amendment (NPA), NPA-E-33 Rev 0, on April 20, 2001. JAA's 
proposed amendment contained rules and advisory material almost 
identical to FAA's proposed part 33 changes. Some commenters to this 
NPA objected that the reliability of aircraft-supplied electrical power 
should be considered when determining the required degree of protection 
against failure. Because of these comments, the JAA updated its 
rulemaking in NPA-E-33 Rev 1. The FAA and the JAA subsequently agreed 
that the reliability and quality of aircraft-supplied power should be a 
factor in considering the approval of the engine design. This NPRM 
reflects this agreement between FAA and the JAA. EASA has adopted this 
agreement as CS-E (Certification Specifications for Engines) 50(h).

Section-by-Section Discussion of the Proposals

Section 33.5

    We propose adding new paragraphs (a)(4), (a)(5), (a)(6) and (b)(4) 
to Sec.  33.5 to require applicants to include additional installation 
information in their instructions for installation. The requirements in 
proposed paragraphs (a)(4), (a)(5) and (b)(4) are currently prescribed 
under Sec.  33.28(a) as part of the control system description. This 
proposal places these requirements in sections consistent with their 
intended purpose.
    Our proposed Sec.  33.5(a)(6) would require that installation 
instructions list the instruments necessary for satisfactory control of 
the engine. It would also require that the limits of accuracy and 
transient response required for satisfactory engine operation be 
identified so that the suitability of the instruments as installed can 
be assessed. Part 33 does not require similar installation information. 
We would harmonize Sec. Sec.  33.5(a)(4), (a)(5) and (b)(4) with CS-E 
20(d), CS-E 30(b), and CS-E 20(d), respectively. Adding Sec.  
33.5(a)(6) would harmonize with CS-E 60(b).

Section 33.7

    We propose adding a new paragraph (d) to this section. This 
paragraph

[[Page 18150]]

would require that the overall limits of accuracy of the engine control 
system and the necessary instruments, as defined in Sec.  33.5(a)(6), 
be considered when determining engine performance and operating 
limitations. Paragraph (d) would harmonize with CS-E 40(g).

Section 33.27

    We propose a new Sec.  33.27(b) that prescribes requirements for 
methods, other than engine control methods, for protecting rotor 
structural integrity during overspeed conditions. These methods would 
include protection methods, such as blade shedding, currently regulated 
under the CS-E but not identified under part 33.

Section 33.28

    We propose changing the title of Sec.  33.28 and the content of its 
paragraphs. The title would be changed from ``Electrical and electronic 
engine control systems'' to ``Engine control systems.'' Currently, 
Sec.  33.28 applies only to electrical and electronic engine control 
systems, while CS-E 50 and associated requirements apply to all types 
of engine control systems, including hydromechanical and reciprocating 
engine controls. The new title reflects the proposed revisions to the 
section which, to harmonize with EASA specifications, would change the 
scope of the proposed rule to include all types of engine control 
systems and devices under Sec.  33.28.

Section 33.28(a)

    Our proposed Sec.  33.28(a) would be titled ``Applicability'' and 
would clarify the systems or devices that are subject to Sec.  33.28 
requirements.

Section 33.28(b)

    We propose replacing existing Sec.  33.28(b) with new Sec.  
33.28(b), ``Validation,'' which prescribes requirements for engine 
control system validation. The new Sec.  33.28(b) consists of new 
paragraphs (b)(1) and (b)(2).
    Our proposed Sec.  33.28(b)(1) requires that applicants demonstrate 
that their engine control system performs its intended function in the 
declared operating conditions, including environmental conditions and 
flight envelope. Part 33 generally requires this showing, but does so 
nonspecifically. This new specific requirement will clarify the 
regulation.
    The proposed Sec.  33.28(b)(1) requires that the engine control 
system comply with Sec. Sec.  33.51, 33.65, and 33.73, as appropriate, 
under all likely system inputs and allowable engine power or thrust 
demands. It also requires that the engine control system allow engine 
power and thrust modulation with adequate sensitivity over the declared 
range of engine operating conditions. The engine control system also 
must not create unacceptable power or thrust oscillations.
    Proposed Sec.  33.28(b)(1) would harmonize the sections in part 33 
that address engine performance and operability requirements with 
similar requirements in CS-E 50.
    Our proposed Sec.  33.28(b)(2) revises requirements located in the 
existing Sec.  33.28(d). Proposed Sec.  33.28(b)(2) would clarify 
environmental testing requirements, including those for High Intensity 
Radiated Fields (HIRF), lightning, and electromagnetic interference 
(EMI) for the engine control system.
    The environmental testing requirements that are part of the 
proposed Sec.  33.28(b) set the installation limitations. Those 
limitations are incorporated into the instructions in accordance with 
Sec.  33.5(b)(4).

Section 33.28(c)

    We propose to revise Sec.  33.28(c) to clarify the requirements for 
control transitions when fault accommodation is implemented through 
alternate modes, channel changes, or changes from primary to back-up 
systems. Proposed Sec.  33.28(c), titled ``Control transitions,'' will 
clarify the need for crew notification if crew action is required as 
part of fault accommodation.

Section 33.28(d)

    Our proposed Sec.  33.28(d) would consist of revised control system 
failure requirements formerly located in Sec.  33.28(c). Proposed Sec.  
33.28(d), titled ``Engine control system failures,'' would consist of 
four paragraphs: Sec.  33.28(d)(1) would address integrity 
requirements, such as Loss of Thrust Control (LOTC) requirements 
consistent with the intended application; Sec.  33.28(d)(2) would 
require accommodation of single failures with respect to LOTC/LOPC 
(Loss of Power Control) events; Sec.  33.28(d)(3) would clarify 
requirements for single failures of electrical or electronic 
components; and Sec.  33.28(d)(4) would add requirements for 
foreseeable failures or malfunctions in the intended aircraft 
installation such as fire and overheat (i.e., local events).
    We considered using the phrase ``essentially single fault 
tolerant'' in proposed paragraph (d)(2) as the standard for measuring 
the compliance of an applicant's engine control system. We have had 
extensive discussions with industry about the meaning of ``essentially 
single fault tolerant.'' However, in reviewing the meaning of 
``essentially,'' we decided that this term introduces sufficient 
ambiguity so that the phrase could not serve as the basis for an 
enforceable standard. We chose, therefore, to remove ``essentially'' 
and to reserve to the Administrator the right to define what is meant 
by ``single fault tolerant.'' We are preparing an advisory circular to 
offer guidance regarding what we mean by ``single fault tolerant'' as 
used in the regulation.

Section 33.28(e)

    Our proposed Sec.  33.28(e), titled ``System safety assessment,'' 
would require a System Safety Assessment (SSA) for the engine control 
system. The SSA would identify faults or failures that would have 
harmful effects on the engine. Proposed Sec.  33.28(e) harmonizes with 
CS-E 50(d).

Section 33.28(f)

    Our proposed Sec.  33.28(f), titled ``Protection systems,'' 
requires protective functions that preserve rotor integrity. Proposed 
Sec.  33.28(f)(1) would include the protection requirements of the 
existing Sec.  33.27(b). Proposed Sec.  33.28(f)(2) adds requirements 
for testing the protection function for availability. Proposed Sec.  
33.28(f)(3) establishes requirements for overspeed protection systems 
implemented through hydromechanical or mechanical means. Proposed Sec.  
33.28(f) harmonizes with CS-E 50(e).

Section 33.28(g)

    Our proposed Sec.  32.28(g), titled ``Software,'' would consist of 
the software requirements for the engine control system currently 
prescribed under Sec.  33.28(e). We are proposing to revise Sec.  
33.28(g) to require that software be consistent with the criticality of 
performed functions. Proposed Sec.  33.28(g) harmonizes with CS-E 
50(f).

Section 33.28(h)

    Our proposed Sec.  33.28(h), titled ``Aircraft-supplied data,'' 
clarifies requirements related to failure of aircraft-supplied data. 
The revision consists of two new paragraphs that prescribe requirements 
for single failures leading to loss, interruption, or corruption of 
aircraft-supplied data or data shared between engines. We propose to 
modify the current FAA requirement for fault accommodation for loss of 
all aircraft-supplied data to require detection and accommodation for 
single failures leading to loss, interruption, or corruption of 
aircraft-supplied data. This accommodation must not result in an 
unacceptable change in thrust or power or an unacceptable change in 
engine

[[Page 18151]]

operating and starting characteristics. Proposed Sec.  33.28(h) 
harmonizes with CS-E 50(g).

Section 33.28(i)

    Our proposed Sec.  33.28(i), titled ``Aircraft-supplied electrical 
power,'' clarifies requirements for the response of the engine control 
system to loss or interruption of electrical power supplied from the 
aircraft. Proposed Sec.  33.28(i) would apply to all electrical power 
supplied to the engine control system, including that supplied from the 
aircraft power system and from the dedicated power source, if required.
    We propose to add requirements to Sec.  33.28(i) that represent 
current industry standard practices but are not in part 33. These 
include a requirement that the applicant define in the instructions for 
installation:
    1. The power characteristics of any power supplied from the 
aircraft to the engine control system; and
    2. The engine control and engine responses to low voltage 
transients outside the declared power supply voltage limitations.
    This action proposes an additional requirement for a dedicated 
power source for the control system to provide sufficient capacity to 
power the functions provided by the control system below idle, such as 
for the auto-relight function.
    With the change in scope of this proposal from electronic engine 
controls to engine controls, it is not our intent that all electrically 
powered engine functions be under the Sec.  33.28(i) requirement for a 
dedicated power source. The loss of some control functions 
traditionally dependent on aircraft-supplied power continues to be 
acceptable. The use of conventional aircraft-supplied power for these 
traditional functions has been acceptable as they, in general, do not 
affect the safe operation of the engine. Examples include:
     Functions without safety significance that are primarily 
performance enhancement functions
     Engine start and ignition
     Thrust reverser deployment
     Anti-icing (engine probe heat)
     Fuel shut-off
    Our proposed Sec.  33.28(i) harmonizes with CS-E 50(h).

Section 33.28(j)

    We propose adding a new Sec.  33.28(j), titled ``Air pressure 
signal,'' that would add safety requirements for air pressure signals 
in the engine control system. It will require that applicants take 
design precautions to minimize system malfunction from ingress of 
foreign matter or blockage of the signal lines by foreign matter or 
ice. Our proposed Sec.  33.28(j) harmonizes with CS-E 50(i).

Section 33.28(k)

    Our proposed Sec.  33.28(k), ``Automatic availability and control 
of engine power for 30-second OEI rating,'' prescribes requirements for 
engines with One-Engine-Inoperative (OEI) capability. This proposal, 
formerly located in Sec.  33.67(d), prescribes a control function that 
more properly is located in the ``Engine control systems'' section. We 
propose moving the contents of Sec.  33.67(d) to 33.28(k). Our proposed 
Sec.  33.28(k) harmonizes with CS-E 50(j).

Section 33.28(l)

    Our proposed Sec.  33.28(l), titled ``Engine shutdown means,'' 
requires that the engine control system provide a rapid means of 
shutting down the engine. Proposed Sec.  33.28(l) harmonizes with CS-E 
50(k).

Section 33.28(m)

    Our proposed Sec.  33.28(m), titled ``Programmable logic devices,'' 
adds safety requirements for programmable logic devices (PLD) that 
include Application-Specific Integrated Circuits and programmable gate 
arrays. We decided to propose new PLD requirements separate from 
software requirements, although the requirements are similar, because 
PLD's combine software and complex hardware. The proposed rule would 
require that development of the devices and associated encoded logic 
used in their design and implementation be at a level equal to the 
hazard level of the functions performed via the devices. Proposed Sec.  
33.28(m) harmonizes with CS-E 50(f).

Section 33.29

    We propose revising Sec.  33.29 by adding new paragraphs (e) 
through (h) to harmonize with CS-E 60, Provision for Instruments.
    The new Sec.  33.29(e) would require that applicants provide 
instrumentation necessary to ensure engine operation in compliance with 
the engine operating limitations. When instrumentation is necessary for 
compliance with the engine requirements, applicants must specify the 
instrumentation in the instructions for installation and include the 
instrumentation as part of the engine type design. The proposed Sec.  
33.29(e) harmonizes with CS-E 60(a).
    The existing Sec.  33.29(a) requirement addresses the prevention of 
incorrect connections of instruments only. Proposed Sec.  33.29(f) 
would require that applicants provide a means to minimize the 
possibility of incorrect fitting of instruments, sensors and 
connectors. Proposed Sec.  33.29(f) harmonizes with CS-E 110(e).
    Currently, part 33 does not address requirements for sensors and 
associated wiring and signal conditioning segregation. Proposed Sec.  
33.29(g) would reduce the probability of faults propagating from the 
instrumentation and monitoring functions to the control functions, or 
vice versa, by prescribing that the probability of propagation of 
faults be consistent with the criticality of the function performed. 
Proposed Sec.  33.29(g) harmonizes with CS-E 60(c).
    Our proposed Sec.  33.29(h) would add new requirements for 
instrumentation that enables the flight crew to monitor the functioning 
of the turbine case cooling system. Proposed Sec.  33.29(h) harmonizes 
with CS-E 60(e).

Section 33.53

    We propose revising the title of Sec.  33.53 from ``Engine 
component tests,'' to ``Engine system and component tests.'' The 
revised title would better identify reciprocating engine control system 
tests that may be conducted under this paragraph. Proposed Sec.  
33.53(a) provides for systems tests if required.

Section 33.91

    We propose changing the title of Sec.  33.91 from ``Engine 
component tests'' to ``Engine system and component tests.'' The revised 
title would better identify engine control system tests, for example, 
system validation testing, that may be required under this paragraph. 
Our proposed Sec.  33.91(a) would provide for systems tests if 
required.

Rulemaking Analyses and Notices

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. 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.
    We are issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701, ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce, including minimum safety 
standards for aircraft engines. This proposed rule is within the scope 
of that authority because it

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updates existing regulations for aircraft engine control systems.

Paperwork Reduction Act

    The Paperwork Reduction Act of 1995 (44 U.S.C. 3507(d)) requires 
that the FAA consider the impact of paperwork and other information 
collection burdens imposed on the public. We determined that this 
proposed rule does not impose any new information collection 
requirements.

International Compatibility

    In keeping with U.S. obligations under the Convention on 
International Civil Aviation, we comply with International Civil 
Aviation Organization (ICAO) Standards and Recommended Practices to the 
maximum extent practicable. We determined that ICAO has no Standards or 
Recommended Practices that correspond to these proposed regulations.

Economic Assessment, Regulatory Flexibility Determination, Trade Impact 
Assessment, and Unfunded Mandates Assessment

    Changes to Federal regulations must undergo several economic 
analyses. First, Executive Order 12866 directs that each Federal agency 
propose or adopt a regulation only upon a determination that the 
benefits of the intended regulation justify its costs. Second, the 
Regulatory Flexibility Act of 1980 (Pub. L. 96-354) requires agencies 
to analyze the economic impact of regulatory changes on small entities. 
Third, the Trade Agreements Act (Pub. L. 96-39) 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 also requires agencies to consider international standards and, 
where appropriate, use them as 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 private sector, of $100 million or 
more annually (adjusted for inflation with base year of 1995). This 
portion of the preamble summarizes the FAA's analysis of the economic 
impacts of this proposed rule.
    Department of Transportation Order DOT 2100.5 prescribes policies 
and procedures for simplification, analysis, and review of regulations. 
If the expected cost impact is so minimal that a proposed or final rule 
does not warrant a full evaluation, this order permits that a statement 
to that effect, and the basis for it, be included in the preamble if a 
full regulatory evaluation of the cost and benefits is not prepared. 
Such a determination has been made for this proposed rule. The 
reasoning for this determination follows.
    The proposed rule reflects current practices and harmonizes FAA 
airworthiness standards for aircraft engine control systems with 
similar requirements recently adopted by EASA. These proposed changes 
to engine control system requirements would establish uniform standards 
for all engine control systems for aircraft engines certificated by 
both U.S. and European countries and would simplify airworthiness 
approvals for import and export. Similar international requirements 
would reduce duplicative testing which would reduce certification 
costs.
    An engine control system is any system or device that controls, 
limits, or monitors engine operation and is necessary for the continued 
airworthiness of the engine. This implies consideration of all control 
system components including the electronic control unit(s), fuel 
metering unit(s), variable-geometry actuators, cables, wires, and 
sensors.
    An engine control system may be composed of several subsystems 
which can include: (1) Fuel control, (2) spark control, (3) 
turbocharger wastegate control, (4) throttle control, and (5) propeller 
governor. A turbine FADEC (Full Authority Digital Engine Control) 
system typically controls the fuel, the variable pitch vanes, the 
engine operability bleeds, the temperature management system and, most 
recently, the ignition and other starting elements. A reciprocating 
engine could be considered to have a FADEC system if any of the 
subsystems are controlled electronically over their full range of 
operation.
    The proposed regulation covers the main engine control system as 
well as the protection systems, for example, overspeed, over-torque, or 
over-temperature. Engine monitoring systems are covered by this 
proposed regulation when they are physically or functionally integrated 
with the control system and they perform functions that affect engine 
safety or are used to effect continued-operation or return-to-service 
decisions.
    The purpose of Sec.  33.28 is to set objectives for the general 
design and functioning of the engine control system. These requirements 
are not intended to replace or supersede other requirements, such as 
Sec.  33.67 for the fuel system. Therefore, individual components of 
the control system, such as alternators, sensors, actuators, should be 
covered, in addition, under other part 33 paragraphs such as Sec.  
33.53 and Sec.  33.91 as appropriate.
    Although the proposed rule would cover all types of engine control 
systems (including hydromechanical and reciprocating engine controls), 
it would not cover one particular simple electro-mechanical device--the 
conventional magneto--because that device is not a true control 
component. On the other hand, the proposed rule would cover subsystems 
controlled by a FADEC because this is considered part of the engine 
control system. FADECs are standard on virtually all new turbine 
engines, and are now being put on some new reciprocating engines also.
    This proposal would lower costs by establishing uniform 
certification standards for all engine control systems certified in the 
United States under part 33 and in European countries under EASA 
regulations, simplifying airworthiness approvals for import and export. 
In addition, a potential for increased safety lies in having more clear 
and explicit regulations, but the FAA was unable to quantify this 
benefit. The FAA concludes that the benefits of this rule justify the 
costs. The FAA requests comments with supporting justification about 
the FAA determination of minimal impact.
    The FAA has, therefore, determined that this proposed rule is not a 
``significant regulatory action'' as defined in section 3(f) of 
Executive Order 12866, and is not ``significant'' as defined in DOT's 
Regulatory Policies and Procedures.

Regulatory Flexibility Determination

    The Regulatory Flexibility Act of 1980 (Pub. L. 96-354) (RFA) 
establishes ``as a principle of regulatory issuance that agencies shall 
endeavor, consistent with the objectives of the rule and of applicable 
statutes, to fit regulatory and informational requirements to the scale 
of the businesses, organizations, and governmental jurisdictions 
subject to regulation. To achieve this principle, agencies are required 
to solicit and consider flexible regulatory proposals and to explain 
the rationale for their actions to assure that such proposals are given 
serious consideration.'' 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 rule will 
have a significant economic impact on a

[[Page 18153]]

substantial number of small entities. If the agency determines that it 
will, the agency must prepare a regulatory flexibility analysis as 
described in the RFA.
    However, if an agency determines that a rule is not expected to 
have a significant economic impact on a substantial number of small 
entities, section 605(b) of the 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.
    The FAA believes that this proposed rule would not have a 
significant economic impact on a substantial number of small entities 
because only one U.S. engine manufacturer meets the definition of small 
business contained in the Small Business Administration's small 
business size standard regulations. Therefore, the FAA certifies that 
this proposed rule would not have a significant economic impact on a 
substantial number of small entities. The FAA solicits comments 
regarding this determination.

Trade Impact Assessment

    The Trade Agreements Act of 1979 (Pub. L. 96-39) 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 rulemaking and determined that it uses 
European standards as the basis for U.S. regulations.

Unfunded Mandates Assessment

    Title II of the Unfunded Mandates Reform Act of 1995 (Pub. L. 104-
4) 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 $128.1 million in lieu of 
$100 million.
    This proposed rule does not contain such a mandate. The 
requirements of Title II 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.

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. We determined that 
this proposed rulemaking action qualifies for the categorical exclusion 
identified in Chapter 3, paragraph 312d 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 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.

List of Subjects in 14 CFR Part 33

    Aircraft, Air transportation, Aviation safety, Safety.

The Proposed Amendment

    In consideration of the foregoing, the Federal Aviation 
Administration proposes to amend chapter I of Title 14, Code of Federal 
Regulations, as follows:

PART 33--AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES

    1. The authority citation for part 33 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701-44702, 44704.
    2. Amend Sec.  33.5 by adding new paragraphs (a)(4), (a)(5), 
(a)(6), and (b)(4), to read as follows:


Sec.  33.5  Instruction manual for installing and operating the engine.

* * * * *
    (a) * * *
    (4) A definition of the physical and functional interfaces with the 
aircraft and aircraft equipment, including the propeller when 
applicable.
    (5) Where an engine system relies on components that are not part 
of the engine type design, the interface conditions and reliability 
requirements for those components upon which engine type certification 
is based must be specified in the engine installation instructions 
directly or by reference to appropriate documentation.
    (6) A list of the instruments necessary for control of the engine, 
including the overall limits of accuracy and transient response 
required of such instruments for control of the operation of the 
engine, must also be stated so that the suitability of the instruments 
as installed may be assessed.
    (b) * * *
    (4) A description of the primary and all alternate modes, and any 
back-up system, together with any associated limitations, of the engine 
control system and its interface with the aircraft systems, including 
the propeller when applicable.
    3. Amend Sec.  33.7 by adding new paragraph (d) to read as follows:


Sec.  33.7  Engine ratings and operating limitations.

* * * * *
    (d) In determining the engine performance and operating 
limitations, the overall limits of accuracy of the engine control 
system and of the necessary instrumentation as defined in Sec.  
33.5(a)(6) must be taken into account.
    4. Amend Sec.  33.27 by revising paragraph (b) to read as follows:


Sec.  33.27  Turbine, compressor, fan, and turbosupercharger rotors.

* * * * *
    (b) The design and functioning of engine systems, instruments, and 
other methods, not covered under Sec.  33.28 of this part must give 
reasonable assurance that those engine operating limitations that 
affect turbine, compressor, fan, and turbosupercharger rotor structural 
integrity will not be exceeded in service.
* * * * *
    5. Revise Sec.  33.28 to read as follows:


Sec.  33.28  Engine control systems.

    (a) Applicability. These requirements are applicable to any system 
or device that is part of engine type design, that controls, limits, or 
monitors engine operation, and is necessary for the continued 
airworthiness of the engine.
    (b) Validation. (1) Functional aspects. The applicant must 
substantiate by tests, analysis, or a combination thereof, that the 
engine control system performs the intended functions in a manner 
which:

[[Page 18154]]

    (i) Enables selected values of relevant control parameters to be 
maintained and the engine kept within the approved operating limits 
over changing atmospheric conditions in the declared flight envelope;
    (ii) Complies with the operability requirements of Sec. Sec.  
33.51, 33.65 and 33.73, as appropriate, under all likely system inputs 
and allowable engine power or thrust demands, unless it can be 
demonstrated that this is not required for non-dispatchable specific 
control modes in the intended application, in which case the engine 
would be approved;
    (iii) Allows modulation of engine power or thrust with adequate 
sensitivity over the declared range of engine operating conditions; and
    (iv) Does not create unacceptable power or thrust oscillations.
    (2) Environmental limits. The applicant must demonstrate, when 
complying with Sec. Sec.  33.53 or 33.91, that the engine control 
system functionality will not be adversely affected by declared 
environmental conditions, including electromagnetic interference (EMI), 
High Intensity Radiated Fields (HIRF), and lightning. The limits to 
which the system has been qualified must be documented in the engine 
installation instructions.
    (c) Control transitions. (1) The applicant must demonstrate that, 
when fault or failure results in a change from one control mode to 
another, from one channel to another, or from the primary system to the 
back-up system, the change occurs so that:
    (i) The engine does not exceed any of its operating limitations;
    (ii) The engine does not surge, stall, or experience unacceptable 
thrust or power changes or oscillations or other unacceptable 
characteristics; and
    (iii) There is a means to alert the flight crew if the crew is 
required to initiate, respond to, or be aware of the control mode 
change. The means to alert the crew must be described in the engine 
installation instructions, and the crew action must be described in the 
engine operating instructions;
    (2) The magnitude of any change in thrust or power and the 
associated transition time must be identified and described in the 
engine installation instructions and the engine operating instructions.
    (d) Engine control system failures. The applicant must design and 
construct the engine control system so that:
    (1) The rate for Loss of Thrust (or Power) Control (LOTC/LOPC) 
events, consistent with the safety objective associated with the 
intended application can be achieved;
    (2) In the full-up configuration, the system is single fault 
tolerant, as determined by the Administrator, for electrical or 
electronic failures with respect to LOTC/LOPC events,
    (3) Single failures of engine control system components do not 
result in a hazardous engine effect, and
    (4) Foreseeable failures or malfunctions leading to local events in 
the intended aircraft installation, such as fire, overheat, or failures 
leading to damage to engine control system components, do not result in 
a hazardous engine effect due to engine control system failures or 
malfunctions.
    (e) System safety assessment. When complying with Sec. Sec.  33.28 
and 33.75, the applicant must complete a System Safety Assessment for 
the engine control system. This assessment must identify faults or 
failures that result in a change in thrust or power, transmission of 
erroneous data, or an effect on engine operability together with the 
predicted frequency of occurrence of these faults or failures.
    (f) Protection systems. (1) The design and functioning of engine 
control devices and systems, together with engine instruments and 
operating and maintenance instructions, must provide reasonable 
assurance that those engine operating limitations that affect turbine, 
compressor, fan, and turbosupercharger rotor structural integrity will 
not be exceeded in service.
    (2) When electronic overspeed protection systems are provided, the 
design must include a means for testing, at least once per engine 
start/stop cycle, to establish the availability of the protection 
function. The means must be such that a complete test of the system can 
be achieved in the minimum number of cycles. If the test is not fully 
automatic, the requirement for a manual test must be contained in the 
engine instructions for operation.
    (3) When overspeed protection is provided through hydromechanical 
or mechanical means, the applicant must demonstrate by test or other 
acceptable means that the overspeed function remains available between 
inspection and maintenance periods.
    (g) Software. The applicant must design, implement, and verify all 
associated software to minimize the existence of errors by using a 
method, approved by the FAA, consistent with the criticality of the 
performed functions.
    (h) Aircraft-supplied data. Single failures leading to loss, 
interruption or corruption of aircraft-supplied data (other than thrust 
or power command signals from the aircraft), or data shared between 
engines must:
    (1) Not result in a hazardous engine effect for any engine; and
    (2) Be detected and accommodated. The accommodation strategy must 
not result in an unacceptable change in thrust or power or an 
unacceptable change in engine operating and starting characteristics. 
The applicant must evaluate and document the effects of these failures 
on engine power or thrust, engine operability, and starting 
characteristics throughout the flight envelope.
    (i) Aircraft-supplied electrical power. (1) The applicant must 
design the engine control system so that the loss, malfunction, or 
interruption of electrical power supplied from the aircraft to the 
engine control system will not result in any of the following:
    (i) A hazardous engine effect, or
    (ii) The unacceptable transmission of erroneous data.
    (2) When an engine dedicated power source is required for 
compliance with Sec.  33.28(i)(1), its capacity should provide 
sufficient margin to account for engine operation below idle where the 
engine control system is designed and expected to recover engine 
operation automatically.
    (3) The applicant must identify and declare the need for, and the 
characteristics of, any electrical power supplied from the aircraft to 
the engine control system for starting and operating the engine, 
including transient and steady state voltage limits, in the engine 
instructions for installation.
    (4) Low voltage transients outside the power supply voltage 
limitations declared in Sec.  33.28(i)(3) must meet the requirements of 
Sec.  33.28(i)(1). The engine control system must be capable of 
resuming normal operation when aircraft-supplied power returns to 
within the declared limits.
    (j) Air pressure signal. The applicant must consider the effects of 
blockage or leakage of the signal lines on the engine control system as 
part of the system safety assessment of Sec.  33.28(e) and must adopt 
the appropriate design precautions.
    (k) Automatic availability and control of engine power for 30-
second OEI rating. Rotorcraft engines having a 30-second OEI rating 
must incorporate a means, or a provision for a means, for automatic 
availability and automatic control of the 30-second OEI power within 
its operating limitations.
    (l) Engine shut down means. Means must be provided for shutting 
down the engine rapidly.
    (m) Programmable logic devices. The development of programmable 
logic

[[Page 18155]]

devices using digital logic or other complex design technologies must 
provide a level of assurance for the encoded logic commensurate with 
the hazard associated with the failure or malfunction of the systems in 
which the devices are located. The applicant must design, implement, 
and verify all associated logic to minimize the existence of errors by 
using a method, approved by the FAA, that is consistent with the 
criticality of the performed function.
    6. Amend Sec.  33.29 by adding new paragraphs (e) through (h) to 
read as follows:


Sec.  33.29  Instrument connection.

* * * * *
    (e) The applicant must make provision for the installation of 
instrumentation necessary to ensure operation in compliance with engine 
operating limitations. Where, in presenting the safety analysis, or 
complying with any other requirement, dependence is placed on 
instrumentation that is not otherwise mandatory in the assumed aircraft 
installation, then the applicant must specify this instrumentation in 
the engine installation instructions and declare it mandatory in the 
engine approval documentation.
    (f) As part of the System Safety Assessment of Sec.  33.28(e), the 
applicant must assess the possibility and subsequent effect of 
incorrect fit of instruments, sensors, or connectors. Where necessary, 
the applicant must take design precautions to prevent incorrect 
configuration of the system.
    (g) The sensors, together with associated wiring and signal 
conditioning, must be segregated, electrically and physically, to the 
extent necessary to ensure that the probability of a fault propagating 
from instrumentation and monitoring functions to control functions, or 
vice versa, is consistent with the failure effect of the fault.
    (h) The applicant must provide instrumentation enabling the flight 
crew to monitor the functioning of the turbine cooling system unless 
appropriate inspections are published in the relevant manuals and 
evidence shows that:
    (1) Other existing instrumentation provides adequate warning of 
failure or impending failure;
    (2) Failure of the cooling system would not lead to hazardous 
engine effects before detection; or
    (3) The probability of failure of the cooling system is extremely 
remote.
    7. Amend Sec.  33.53 by revising the section heading and paragraph 
(a) to read as follows:


Sec.  33.53  Engine system and component tests.

    (a) For those systems and components that cannot be adequately 
substantiated in accordance with endurance testing of Sec.  33.49, the 
applicant must conduct additional tests to demonstrate that systems or 
components are able to perform the intended functions in all declared 
environmental and operating conditions.
* * * * *


Sec.  33.67  [Amended]

    8. Remove paragraph (d) from Sec.  33.67.
    9. Amend Sec.  33.91 by revising the section heading and paragraph 
(a) to read as follows:


Sec.  33.91  Engine system and component tests.

    (a) For those systems or components that cannot be adequately 
substantiated in accordance with endurance testing of Sec.  33.87, the 
applicant must conduct additional tests to demonstrate that the systems 
or components are able to perform the intended functions in all 
declared environmental and operating conditions.
* * * * *

    Issued in Washington, DC, on March 26, 2007.
John J. Hickey,
Director, Aircraft Certification Service.
[FR Doc. E7-6535 Filed 4-10-07; 8:45 am]
BILLING CODE 4910-13-P