[Federal Register Volume 74, Number 157 (Monday, August 17, 2009)]
[Proposed Rules]
[Pages 41522-41556]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E9-19350]



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Part III





Department of Transportation





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Federal Aviation Administration



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14 CFR Parts 1 and 23



Certification of Turbojets; Proposed Rule

  Federal Register / Vol. 74, No. 157 / Monday, August 17, 2009 / 
Proposed Rules  

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Parts 1 and 23

[Docket No. FAA-2009-0738; Notice No. 09-09]
RIN 2120-AJ22


Certification of Turbojets

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This action proposes to enhance safety by amending the 
applicable standards for part 23 turbojet-powered airplanes--which are 
commonly referred to as ``turbojets''--to reflect the current needs of 
industry, accommodate future trends, address emerging technologies, and 
provide for future airplane operations. This action is necessary to 
eliminate the current workload of processing exemptions, special 
conditions, and equivalent levels of safety findings necessary to 
certificate light part 23 turbojets. The intended effect of the 
proposed changes would: Standardize and simplify the certification of 
part 23 turbojets; clarify areas of frequent non-standardization and 
misinterpretation, particularly for electronic equipment and system 
certification; and codify existing certification requirements in 
special conditions for new turbojets that incorporate new technologies.

DATES: Send your comments on or before November 16, 2009.

ADDRESSES: You may send comments identified by Docket Number FAA-2009-
0738 using any of the following methods:
     Federal eRulemaking Portal: Go to http://www.regulations.gov and follow the online instructions for sending your 
comments electronically.
     Mail: Send comments to Docket Operations, M-30, U.S. 
Department of Transportation, 1200 New Jersey Avenue, SE., Room W12-
140, West Building Ground Floor, Washington, DC 20590-0001.
     Hand Delivery or Courier: Bring comments to Docket 
Operations in Room W12-140 of the West Building Ground Floor at 1200 
New Jersey Avenue, SE., Washington, DC, between 9 a.m. and 5 p.m., 
Monday through Friday, except Federal holidays.
     Fax: Fax comments to Docket Operations at 202-493-2251.

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://www.regulations.gov, including any personal information you 
provide. Using the search function of our docket Web site, anyone can 
find and read the electronic form of all comments received into any of 
our dockets, including the name of the individual sending the comment 
(or signing the comment for 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://DocketsInfo.dot.gov.
    Docket: To read background documents or comments received, go to 
http://www.regulations.gov at any time and follow the online 
instructions for accessing the docket. Or, go to Docket Operations in 
Room W12-140 of the West Building Ground Floor at 1200 New Jersey 
Avenue, SE., Washington, DC, between 9 a.m. and 5 p.m., Monday through 
Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT: For technical questions concerning 
this proposed rule, contact Pat Mullen, Regulations and Policy, ACE-
111, Federal Aviation Administration, 901 Locust St., Kansas City, MO 
64106; telephone: (816) 329-4111; facsimile (816) 329-4090; e-mail: 
[email protected]. For legal questions concerning this proposed rule, 
contact Mary Ellen Loftus, ACE-7, Federal Aviation Administration, 901 
Locust St., Kansas City, MO 64106; telephone: (816) 329-3764; e-mail: 
[email protected].

SUPPLEMENTARY INFORMATION: Later in this preamble under the Additional 
Information section, we discuss how you can comment on this proposal 
and how we will handle your comments. Included in this discussion is 
related information about the docket, privacy, and the handling of 
proprietary or confidential business information. We also discuss how 
you can get a copy of this proposal and related rulemaking documents.

Authority for This Rulemaking

    The FAA's authority to issue rules on 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. Under that section, 
the FAA is charged with promoting safe flight of civil airplanes in air 
commerce by prescribing minimum standards required in the interest of 
safety for the design and performance of airplanes. This regulation is 
within the scope of that authority because it prescribes new safety 
standards for the design of normal, utility, acrobatic, and commuter 
category airplanes.

Table of Contents

I. Background
    A. Historical Certification Requirements Overview
    B. Aviation Rulemaking Committee (ARC) Recommendations
    C. Proposed Regulatory Requirements Overview
II. Discussion of the Proposed Regulatory Requirements
III. Regulatory Notices and Analyses
IV. The Proposed Amendments

I. Background

A. Historical Certification Requirements Overview

    Title 14 Code of Federal Regulations (14 CFR) part 23 provides the 
airworthiness standards for Normal, Utility, Acrobatic, and Commuter 
Category Airplanes. The first application for the certification of a 
turbojet airplane under part 23 occurred in the 1970s before many of 
the current turbine requirements were added to part 23. Prior to this, 
turbojet powered airplanes were certificated to the standards under 
part 25. Part 25 provides the airworthiness standards for Transport 
category airplanes. A turbojet is a jet engine that develops thrust 
using a turbine compressor which is propelled by high speed exhaust 
gases expelled as a jet. The FAA implemented many of the certification 
requirements for early part 23 turbojets through special conditions 
based on 14 CFR part 25 (pre-amendment 25-42, (43 FR 2320)) 
requirements. Almost all special conditions applied to turbojets were 
for part 23, subpart B, Flight, and subpart G, Operating Limitations 
and Information.
    Special conditions for part 23 certification increased performance 
requirements for emerging turbojets similar to those covered by early 
part 25 standards. The FAA established these special conditions to 
ensure a minimum one-engine inoperative (OEI) performance level that 
would be included in the airplane's limitations, thereby guaranteeing 
single-engine climb performance. The level of safety provided by the 
special conditions was purposely higher for the early turbojets than 
for propeller-driven airplanes in the same weight band because the 
manufacturers and the FAA wanted part 23 turbojets to be similar to 
part 25

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business jets. Special conditions also addressed the following safety 
concerns: (1) The lack of turbine requirements in part 23, (2) the 
sensitivity of turbine engines to altitude and temperature effects, and 
(3) the high takeoff and landing speeds associated with turbojets that 
typically required long takeoff and landing distances, as compared to 
the performance of reciprocating, multiengine airplanes of that era.
    In the mid-1990s, the FAA hosted a meeting for flight test pilot 
representatives from the Aircraft Certification Offices. The purpose of 
that meeting was to discuss how emerging 600 to 1,200 pound thrust 
engines were being developed and how the FAA would certificate future 
turbojet programs. The participants considered the prospect for small 
single- and multi-engine turbojets. At that time, the FAA assumed that 
any new part 23 turbojet would have similar characteristics to any 
existing small part 25 turbojet. However, using the preliminary design 
estimates from several new turbojets, FAA flight test personnel 
realized these assumptions were outdated. Therefore, the FAA needed to 
reevaluate its certification standards for turbojets against existing 
light-weight airplanes.
    The meeting participants did not want to discourage development of 
small part 23 turbojets by applying significantly higher standards than 
for an equivalent propeller airplane. Therefore, the participants 
decided the best approach for future turbojet certification programs 
was to apply the existing part 23 weight differentiator of 6,000 pounds 
in establishing requirements.

B. Aviation Rulemaking Committee (ARC) Recommendations

    On February 3, 2003, we published a notice announcing the creation 
of the part 125/135 Aviation Rulemaking Committee.\1\ Part 125 
addresses the certification and operations of airplanes having a 
seating capacity of 20 or more passengers or a maximum payload capacity 
of 6,000 pounds or more. Part 135 addresses the operating requirements 
for commuter and on-demand operations and rules governing persons on 
board such aircraft. Since some part 23 airplanes operate under parts 
125 or 135, the ARC provided recommendations to the FAA for safety 
standards applicable for part 23 turbojet airplanes to reflect the 
current industry, industry trends, emerging technologies and operations 
under parts 125 and 135, and associated regulations. The ARC also 
reviewed the existing part 23 certification requirements and the 
accident history of light piston-powered, multiengine airplanes up 
through small turbojets used privately and for business. In addition, 
the ARC reviewed the special conditions applied to part 23 turbojets. 
The ARC completed its work in 2005 and submitted its recommendations to 
the FAA. Those documents may be reviewed in the docket for this 
proposed rule. The ARC recommended modifying forty-one 14 CFR part 23 
sections as a result of its review of these areas.
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    \1\ 68 FR 5488
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    As stated earlier, the FAA's intent is to codify standards 
consistent with the level of safety currently required through special 
conditions. We compared the special conditions applied to part 23 
turbojets, as well as several additional proposed part 23 changes, with 
the ARC's recommendations. With few exceptions, the ARC recommendations 
validated the FAA's long-held approach to certification of part 23 
turbojets.
    The ARC did not want to impose commuter category takeoff speeds for 
turbojets above 6,000 pounds, nor did the ARC want to impose more 
stringent requirements for one-engine inoperative (OEI) climb 
performance than those established for similar-sized piston-powered and 
turboprop multiengine airplanes. The FAA ultimately accepted thirty-
nine of the forty-one ARC recommendations and developed this proposed 
rulemaking in accordance with them. The two recommendations we 
disagreed with would have lowered the standards previously applied 
through special conditions.

C. Proposed Regulatory Requirements Overview

    The FAA currently issues type certificates (TCs) to part 23 
turbojets using extensive special conditions, exemptions, and 
equivalent levels of safety (ELOS). Until recently, this practice of 
using special conditions, exemptions, and ELOS did not represent a 
significant workload because there were relatively few part 23 turbojet 
programs. However, in the past five years, the number of new part 23 
turbojet type certification programs has increased more than 100 
percent over the program numbers of the past three decades. The need to 
incorporate special conditions, exemptions, and ELOS into part 23 stems 
from this rise in the number of new turbojet programs and the expected 
growth in the number of future programs. Codifying special conditions 
would standardize and clarify the requirements for manufacturers during 
the design phase of turbojets. Doing so would prevent instances where 
manufacturers design turbojets and later have to demonstrate compliance 
with special conditions that may require redesign. Codifying special 
conditions, exemptions, and ELOS would also eliminate the 
manufacturers' and the FAA's workload associated with processing these 
documents and could reduce potential delays to project schedules. Many 
of the proposed changes in this notice would codify certification 
requirements and practices currently accomplished through use of 
special conditions, exemptions, and ELOS.
    We propose changes to part 1 definitions to clarify new 
requirements proposed for part 23. In addition, we propose changes to 
part 23 in the areas of:
     Airplane categories to allow commuter category 
certification of multiengine turbojets;
     Flight requirements, including standards for performance, 
stability, stalls, and other flight characteristics;
     Structure requirements, including standards for emergency 
landing conditions and fatigue evaluation;
     Design and construction requirements, including standards 
for flutter, takeoff warning system, brakes, personnel and cargo 
accommodations, pressurization, and fire protection;
     Powerplant requirements, including standards for engines, 
powerplant controls and accessories, and powerplant fire protection;
     Equipment requirements, including general equipment 
standards and standards for instruments installation, electrical 
systems and equipment, and oxygen systems; and
     Operating limitations and information, including standards 
for airspeed limitations, kinds of operation, markings and placards, 
and airplane flight manual and approved manual material.

II. Discussion of the Proposed Regulatory Amendments

1. Part 1: Definitions Clarifying Power and Engine Terms

    We propose to amend part 1 definitions for ``rated takeoff power,'' 
``rated takeoff thrust,'' ``turbine engine,'' ``turbojet engine,'' and 
``turboprop engine.'' Defining engine-specific terms would clarify the 
new requirements proposed for part 23. The need to define some of these 
terms was also shown by the following communications between the FAA 
and members of industry. These communications were based on the 
existing part 1 definitions for ``rated takeoff power'' and ``rated 
takeoff thrust'', which limit the use of these

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power and thrust ratings to no more than five minutes for takeoff 
operation.
    In 1990, the Airline Transport Association (ATA) sent a letter to 
the FAA asking the FAA to allow 10-minute OEI takeoff approval. At some 
airports (mostly foreign), the climb gradient capability needed to 
clear distant obstacles after takeoff requires more time at takeoff 
thrust than 5 minutes. Using only 5 minutes of takeoff thrust to clear 
distant obstacles limits the maximum allowable airplane takeoff weight. 
The availability of takeoff thrust or power for use up to 10 minutes, 
granted by some foreign authorities, enabled some foreign operators to 
dispatch at an increased gross weight over that allowed for U.S. 
operators. U.S. operators asked for equal treatment in similar 
circumstances. The FAA has approved these requests when they have been 
properly substantiated. This policy would also apply to operators of 
part 23 turbojet-powered airplanes in order to achieve a climb gradient 
necessary to clear obstacles.

2. Expanding Commuter Category to Include Turbojets

    Currently, we limit commuter category airplane requirements to 
propeller-driven, multiengine airplanes. The FAA has issued exemptions 
to allow turbojets weighing more than 12,500 pounds to be certificated 
under part 23. The proposal to change Sec.  23.3 would codify the 
current FAA practice of certificating multiengine turbojets weighing up 
to and including 19,000 pounds under part 23 in the commuter category.

3. Performance, Flight Characteristics, and Other Design Considerations

a. Performance
    We propose to extend the commuter category performance requirements 
to multiengine turbojets weighing more than 6,000 pounds. This proposal 
codifies requirements that we currently impose by special conditions 
for these airplanes. Amendment 23-45 (58 FR 42136) requires all 
turbine-powered airplanes weighing 6,000 pounds or less to meet many of 
the same performance standards for reciprocating-powered airplanes 
weighing more than 6,000 pounds. The FAA has determined that turbojets 
should meet a higher level of safety than reciprocating-powered 
airplanes in the same weight band. By requiring turbojets over 6,000 
pounds to meet the higher commuter category certification requirements, 
the FAA would remain consistent in establishing more stringent 
requirements for turbojet airplanes than for reciprocating airplanes.
    The ARC recommended no changes to performance requirements in 
Sec. Sec.  23.51, 23.53, 23.55, 23.57, 23.59 and 23.61. The ARC pointed 
out that applying the commuter category takeoff performance 
requirements to multiengine turbojets weighing more than 6,000 pounds 
would include restrictions that could become a takeoff weight 
limitation for operations. The ARC stated that these requirements are 
too restrictive for part 91 operations. However, existing multiengine 
turbojets weighing more than 6,000 pounds are required to meet these 
standards through special conditions, and we have seen negligible 
operational impact. We have no rationale or basis to support a reduced 
level of safety for part 23 turbojets.
    The ARC also reviewed FAA and Flight Safety Foundation accident 
studies for engine failure on takeoff. The ARC determined that existing 
normal category part 23 turboprops operated under part 135 have an 
acceptable safety record when compared to turbojets. Furthermore, 
turboprops in the accident studies were not certificated with any of 
the commuter category performance requirements for climb gradients.
    The ARC believed the safety record of the turboprops had more to do 
with the inherent reliability of turbine engines rather than the higher 
climb gradient. An ARC member suggested the higher OEI climb gradients 
originated in part 25 during the large piston transport airplane engine 
era. Back then, the large piston engines were prone to failure on 
takeoff or initial climb, and the requirements for OEI climb gradients 
were necessary for safety.
    The ARC further believed raising the OEI climb performance 
requirements for most multiengine airplanes was appropriate. However, 
the ARC debated the appropriate OEI climb gradients for turbine-powered 
airplanes over 6,000 pounds. Based on the reliability of turbine 
engines, the ARC only recommended raising the climb performance to 1 
percent. This matched the ARC's recommendation of 1 percent for 
turbojets under 6,000 pounds. The ARC's recommendation, however, would 
reduce the OEI climb performance that is currently required through 
special conditions from 2 to 1 percent for turbojet-powered airplanes 
over 6,000 pounds.
    Existing multiengine turbojets weighing more than 6,000 pounds are 
required through special conditions to meet the commuter category 
performance requirements (2 percent climb gradient) for OEI. We propose 
to maintain the 2 percent OEI climb gradient currently applied through 
special conditions for multiengine turbojets over 6,000 pounds. This 
climb gradient requirement is safe and prudent, and it is not 
reasonable to reduce the level of safety that already exists with part 
23 turbojets.
    Although special conditions have required 2 percent OEI climb 
gradient for multiengine turbojets over 6,000 pounds, there was no data 
to support whether small turbojets under 6,000 pounds could meet the 
higher 2 percent climb gradient while maintaining reasonable utility. 
If our rule changes to Sec. Sec.  23.63 and 23.67 negatively impacted 
their utility (i.e., weight-carrying ability), the rule might give the 
piston-powered, multiengine airplanes a distinct market advantage. 
Accident studies show that turbojets are generally safer than piston-
powered airplanes. Therefore, we wanted to compromise by proposing a 
requirement that would provide an adequate minimum safety standard and 
encourage production of more turbojets. One multiengine turbojet in 
this weight band has been operated as an air taxi, and the FAA expects 
this type of operation to grow. While this particular jet is capable of 
higher climb performance, we propose only to increase the OEI climb 
performance requirement to 1.2 percent because other jets in this 
weight band may not be capable of the higher 2 percent climb 
performance. Based on accident data, 1.2 percent provides an adequate 
minimum safety standard.
    Historically, piston-powered, multiengine airplanes were allowed a 
lower climb requirement because they would not have any weight-carrying 
utility if forced to meet the same requirements of the larger 
airplanes. We are continuing this philosophy in this proposal. (See 
summary in the table below.)

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             Table 1--One-Engine Inoperative Climb Requirements to 400 Feet Above Ground Level (AGL)
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                                                                                     ARC
  Multiengine type/airplane weight band               Current rule             recommendation     FAA proposal
                                                                                  (percent)         (percent)
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Pistons >6,000 lbs.......................  Measurably positive..............               1.0               1.0
Turboprops <=6,000 lbs...................  Measurably positive..............               1.0               1.0
Turboprops >6,000 lbs....................  Measurably positive..............               1.0               1.0
Turbojets <=6,000 lbs....................  Measurably positive..............               1.0               1.2
Turbojets >6,000 lbs.....................  2.0 percent imposed through                     1.0               2.0
                                            special conditions.
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    In addition to the proposed changes in takeoff and climb 
performance requirements described above, we also propose changes to 
other performance rules. Currently, part 23 reflects the traditional 
small airplane definition of landing configuration stall speed 
(VSO). However, certification personnel have interpreted 
VSO in part 23 as being the same as that in part 25. This 
interpretation has resulted in an unnecessary burden to the applicant. 
We are revising the part 23 requirement so that it is distinct from the 
part 25 requirement and to retain the original definition of the term. 
We are proposing to revise paragraphs (a) and (c) of Sec.  23.49 to 
clarify the section. We are also proposing to correct the title of this 
section in the CFR to ``Stalling speed'' instead of ``Stalling 
period.''
    VSO, by definition, is the stall speed in the maximum 
landing flap configuration and is not applicable to other flap 
configurations. (V speeds are defined in part 1. To simplify the 
understanding of the proposed rule, we are adding this information 
here.) Current Sec.  23.73 references VSO. The reference to 
VSO in this paragraph is an error and should be changed to 
reference the stall speed for a specified flap configuration 
(VS1). The reference landing approach speed 
(VREF) should be based on 1.3 times the VS1. We 
propose to amend the standards to address airplanes certificated under 
part 23 that may have more than one landing flap setting. We also 
propose to apply the commuter category requirements for VREF 
to multiengine turbojets over 6,000 pounds maximum weight. In addition, 
we propose to apply the commuter category requirements for balked 
landings in Sec.  23.77 to all multiengine turbine-powered airplanes 
over 6,000 pounds, consistent with current special conditions for 
multiengine turbojets and turbine-powered airplanes over 6,000 pounds.
b. Flight Characteristics
    The FAA proposes to define ``maximum allowable speed'' and to 
clarify the specific speed limitations, which include specific criteria 
for VFC, VLE, or VFC/MFC as 
appropriate. The proposal for Sec.  23.177 would codify special 
conditions that include specific speed limitations. Furthermore, we are 
adding a new paragraph to Sec.  23.175(b) to define the VFC/
MFC (maximum speed for stability characteristics) term in 
part 23. This definition was inadvertently omitted in the last revision 
to part 23.
    The FAA proposes to amend the combined lateral-directional dynamic 
stability damping requirements for airplanes that operate above 18,000 
feet. The existing stability damping requirements, which apply at all 
certificated altitudes, were developed when small airplanes typically 
operated under 18,000 feet and were not equipped with yaw dampers. The 
existing requirement remains appropriate for low altitude operations, 
such as for approaches, but it is not appropriate for larger airplanes 
that typically use yaw dampers and fly at altitudes well above 18,000 
feet. The FAA has issued exemptions for most turbojets certificated 
under part 23 because it is appropriate for high-altitude, high-speed 
operations. The proposed changes to Sec.  23.181 would reduce the 
stability damping requirement at 18,000 feet and above. If adopted, 
this amendment would reduce the number of exemptions processed by the 
FAA by codifying what is allowed as an acceptable means of compliance.
    The FAA proposes to amend the existing stall requirements in 
Sec. Sec.  23.201 and 23.203 to include language from the turbojet 
special conditions. We propose clarifying the requirements for wings-
level and accelerated turning stalls. We also propose changing the 
roll-off requirements for wings-level, high-altitude stalls.
    The FAA proposes additional high-speed and high-altitude 
requirements to Sec. Sec.  23.251 and 23.253 to address the new 
generation of high performance part 23 airplanes. The FAA also proposes 
to extend provisions from part 25, Sec. Sec.  25.251(d) and (e), to 
part 23. However, we would limit the requirements to airplanes that fly 
over 25,000 feet and have a Mach dive speed (MD) faster than 
Mach 0.6 (M 0.6) to be consistent with part 25 requirements. The FAA 
also proposes the use of VDF/MDF, which is 
demonstrated flight dive speed (VDF) or Mach 
(MDF) as referenced in the part 23 turbojet special 
conditions.
    Furthermore, we propose adding requirements in a new Sec.  23.255 
that would be based on Sec.  25.255 and would address potential high-
speed Mach effects for airplanes with MD greater than M 0.6. 
The FAA's approach would only apply the part 25-based requirements to 
airplanes that incorporate a trimmable horizontal stabilizer, which is 
consistent with the ARC's recommendation. The ARC's recommendation was 
based on the positive service history with the existing fleet of part 
23 and part 25 turbojets designed with conventional horizontal tails 
that use trimmable elevators. The industry manufacturers have designed 
airplanes that have experienced upset incidents involving out-of-trim 
conditions with a trimmable horizontal stabilizer. Service experience 
shows that out-of-trim conditions can occur in flight for various 
reasons, and the control and maneuvering characteristics of the 
airplane may be critical in recovering from upsets. The proposed 
language would require exploring the airplane's high-speed control and 
maneuvering characteristics.
c. Other Design Considerations
    We propose to revise language in Sec.  23.703 in the introductory 
text and paragraph (b) to add takeoff warning system requirements to 
all airplanes over 6,000 pounds and all turbojets. The definition of an 
unsafe condition, in this case, is the inability to rotate or prevent 
an immediate stall after rotation. High temporary control forces that 
can be quickly ``trimmed out'' would not necessarily be considered 
unsafe.
    We have proposed the commuter category, rejected takeoff 
requirements for all multiengine turbojets over 6,000 pounds. The 
higher takeoff speeds and distances for these airplanes make the 
ability to stop in a specified distance a safety issue. Additional 
braking considerations accompany the rejected

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takeoff requirements. Therefore, we propose to apply the requirements 
for brakes in Sec.  23.735 to all multiengine turbojets over 6,000 
pounds, as well as to all commuter category airplanes.

4. Structural Considerations for Crashworthiness and High-Altitude 
Operations

    The FAA proposes to codify into Sec.  23.561 the recent turbojet 
special conditions that were not available during the ARC's effort. 
This proposal applies to single-engine turbojets with centerline 
engines embedded in the fuselage. Part 23 did not encompass embedded 
centerline engine installations, except for in-line propeller-pusher 
types. In light of several new turbojet designs, it is prudent to 
require greater engine retention strength for engines mounted aft of 
the cabin. This is especially true for engines mounted inside the 
fuselage behind the passengers. The proposed requirement would reduce 
the potential for the engine to separate from its mounts under forward-
acting crash loads and subsequently intrude into the cabin. We recently 
applied this proposed requirement to a single-engine turbojet through 
special conditions.
    The ARC did not consider emergency landing dynamic conditions in 
Sec.  23.562. We recognize, however, that Sec.  23.562 should be 
applicable to all turbojets, including those operating in the commuter 
category. All manufacturers of recently certificated commuter category 
turbojets have agreed to comply with Sec.  23.562. The FAA proposes to 
amend Sec.  23.562 to include all commuter category turbojets. This 
proposal would adopt current industry practice and ensure a consistent 
level of safety for all turbojets.
    At one time, the FAA proposed to apply the requirements for 
emergency landing dynamic conditions to all commuter category 
airplanes.\2\ Subsequently, we published new certification and 
operations requirements for commuter operations.\3\ These actions 
required certain commuter operators that previously conducted 
operations under part 135 to conduct those operations under part 121. 
This rule, in effect, eliminated the use of new part 23 airplanes with 
10 seats or more in scheduled service. This action negated any 
projected benefits supporting the addition of emergency landing dynamic 
conditions to commuter category airplanes.
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    \2\ 58 FR 38028.
    \3\ 60 FR 65832 and 61 FR 2608.
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    The commuter operators affected were those conducting scheduled 
passenger-carrying operations in airplanes that have passenger-seating 
configurations of 10 to 30 seats (excluding any crewmember seat) and 
those conducting scheduled passenger-carrying operations in turbojet 
airplanes regardless of seating configuration. The action increased 
safety in scheduled passenger-carrying operations and clarified, 
updated, and consolidated the certification and operations requirements 
for persons who transport passengers or property by air for 
compensation or hire.
    In terms of overall configuration, commuter category turbojets have 
little resemblance to their propeller-driven counterparts. During an 
emergency landing, most commuter category turbojets will have more 
structure underneath the cabin floor available to absorb energy than 
traditional propeller-driven airplanes. This capability, along with the 
differences in the overall airplane configuration of turbojets, would 
suggest the test conditions specified in the current rule should be 
applicable to all turbojets. However, commuter category airplanes 
cannot exceed a maximum takeoff weight of 19,000 pounds. With this 
limitation, the amount of crushable, energy absorbing structure is 
small when compared to most part 25 airplanes. For this reason, we 
propose to require the dynamic test conditions specified in part 23 
rather than those in Sec.  25.562.
    We also propose to modify the seating head injury criteria (HIC) 
calculation in the proposed rule to be consistent with the HIC 
definition in part 25. This proposal addresses the concern that the HIC 
definition in part 23 would lead to a HIC calculation only for the 
total time of the head impact, which would not necessarily maximize 
HIC.
    In the event of a ditching, the proposed change in Sec.  23.807 
would provide an alternative to meeting the current requirement for an 
emergency exit, above the waterline, on both sides of the cabin for 
multiengine airplanes. Proposed section 23.807 would allow the 
placement of a water barrier in the doorway before the door would be 
opened as a means to comply with the above waterline exit requirement. 
This barrier would be used to slow the inflow of water. The FAA has 
approved the use of this barrier as an alternative to the above 
waterline exit for several airplanes by issuing an ELOS finding.
    Several new part 23 turbojet programs include approval for 
operations at altitudes above 40,000 feet. Additionally, the FAA has 
issued special conditions for operations up to 49,000 feet. We propose 
rule changes for structures and the cabin environment to ensure 
structural integrity of the airplane at higher altitudes. We also 
propose rule changes to prevent exposure of the occupants to cabin 
pressure altitudes that could cause them physiological injury or 
prevent the flight crew from safely flying and landing the airplane.
    We propose to amend Sec.  23.831 to add new paragraphs (c) and (d), 
which include standards appropriate for airplanes operating at high 
altitudes beyond those included in part 23. The proposed changes are 
intended to ensure flight deck and cabin environments do not result in 
the crew's mental errors or physical exhaustion that would prevent the 
crew from successfully completing assigned tasks for continued safe 
flight and landing. An applicant may demonstrate compliance with 
paragraph (d) of this requirement if the applicant can show that the 
flight deck crew's performance is not degraded.
    The cabin environment must be conservatively specified such that no 
occupant would incur any permanent physiological harm after 
depressurization. The environmental and physiological performance 
limits used for demonstrating compliance must originate from recognized 
and cognizant authorities as accepted by the regulatory authority 
reviewing the compliance finding.
    As part of the certification process, we would consider the entire 
flight profile of the airplane during the depressurization event. The 
profile would include cruise and transient conditions during descent, 
approach, landing, and rollout to a stop on the runway. We would not 
include taxiing as a compliance consideration because the airplane 
would be on the ground and could be evacuated, or flight deck windows 
and cabin doors could be opened for ventilation. The condition of the 
airplane from the beginning of the event to the end of the landing roll 
is accounted for when assessing the safe exit of an airplane.
    We chose the words ``* * * shall not adversely affect crew 
performance * * *'' to mean the crew can be expected to reliably 
perform either their published or trained duties, or both, to complete 
a safe flight and landing. We have measured this in the past by a 
person's ability to track and perform tasks. The event should not 
result in expecting the crew to perform tasks beyond the procedures 
defined by the manufacturer or required by existing regulations. We use 
the phrase ``No occupant shall sustain permanent physiological harm'' 
to mean the occupants who may have required some

[[Page 41527]]

form of assistance, once treated, must be expected to return to their 
normal activities.
    To show compliance to the proposed rule, the applicant should 
consider what would happen to the airplane and systems during 
depressurization. The applicant may also consider operational 
provisions, which provide for or mitigate the resulting environmental 
effects to airplane occupants. If the manufacturer provides an approved 
procedure(s) for depressurization, the flight deck and cabin crew may 
configure the airplane to moderate either temperature or humidity 
extremes, or both, on the flight deck and in the cabin. This 
configuration may include turning off non-critical electrical equipment 
and opening the flight deck door, or opening the flight deck window(s).
    As with Sec.  23.831, we find it necessary to amend the standards 
in Sec.  23.841 to prevent exposure of the occupants to cabin pressure 
altitudes that could keep the flight crew from safely flying and 
landing the airplane or cause permanent physiological injury to the 
occupants. The intent of the proposed changes to Sec.  23.841 is to 
provide airworthiness standards that allow subsonic, pressurized 
turbojets to operate at their maximum achievable altitudes--the highest 
altitude an applicant can choose to demonstrate the effects to several 
occupant related items after decompression. The applicant must show 
that: (1) The flight crew would remain alert and be able to fly the 
airplane, (2) the cabin occupants would be protected from the effects 
of hypoxia (i.e., deprivation of adequate oxygen supply), and (3) if 
some occupants do not receive supplemental oxygen, they would be 
protected against permanent physiological harm.
    Existing rules require the cabin pressure control system maintain 
the cabin at an altitude of not more than 15,000 feet if any probable 
failure or malfunction in the pressurization system occurs. Cabin 
pressure control systems on part 23 airplanes frequently exhibit a 
slight overshoot above 15,000 feet cabin altitude before stabilizing 
below 15,000 feet. Existing technology for cabin pressure control 
systems on part 23 airplanes cannot prevent this momentary overshoot, 
which prevents strict compliance with the rule. We have granted ELOS 
findings for this characteristic because physiological data shows the 
brief duration of the overshoot would have no significant effect on an 
airplane's occupants.
    Special conditions issued for part 23 turbojets are similar and, 
for operating altitudes above 41,000 feet, equivalent to the 
requirements in Sec.  25.841 adopted in Amendment 25-87 (61 FR 28684). 
That amendment revised Sec.  25.841(a) to include requirements for 
pressurized cabins that were previously covered only in special 
conditions. The special conditions required consideration of specific 
failures. The FAA incorporated reliability, probability, and damage 
tolerance concepts addressing other failures and methods of analysis 
into part 25 after the issuance of the special conditions. Sections 
23.571, 23.573, and 23.574 address damage tolerance requirements. We 
propose to require the use of these additional methods of analysis as 
part of this rulemaking.
    This proposal also specifies a more performance-based criterion, 
such that failures cannot adversely affect crew performance nor result 
in permanent physiological harm to passengers.

    (Note: There is a different standard for the crew than the 
passengers.)

    Part 23 requires a warning of an excessive cabin altitude at 10,000 
feet. Those regulations do not adequately address airfield operation 
above 10,000 feet. Rather than disable the cabin altitude warning to 
prevent nuisance warnings, we have issued ELOS findings that allow the 
warning altitude setting to be shifted above the maximum approved field 
elevation, not to exceed 15,000 feet. We propose to revise Sec.  23.841 
to incorporate language from existing ELOSs into the regulation.
    Currently, we address oxygen systems for airplanes operating above 
41,000 feet using special conditions derived from part 25. A large 
number of new turbojets and high-performance airplanes entering part 23 
certification will operate at higher altitudes than previously 
envisioned for part 23 airplanes. We are proposing revisions to 
Sec. Sec.  23.1443, 23.1445, and 23.1447 to establish requirements for 
oxygen systems. These new requirements would eliminate the need for 
special conditions for airplanes operating above 40,000 feet.

5. General Fire Protection and Flammability Standards for Insulation 
Materials

    When we initially introduced powerplant fire protection provisions 
in part 23, we did not foresee turbojet engines embedded in the 
fuselage, nor in pylons on the aft fuselage, for airplanes certificated 
to part 23 standards. We propose to add fire protection requirements 
for turbojets in Sec. Sec.  23.1193, 23.1195, 23.1197, 23.1199, and 
23.1201. Part 23 has historically addressed fire protection through 
prevention, identification, and containment. Manufacturers have 
provided prevention through minimizing the potential for ignition of 
flammable fluids and vapors. Also historically, pilots had been able to 
see the engines and identify the fire or use the incorporated fire 
detection systems, or both. The ability to see the engine provided for 
the rapid detection of a fire, which led to a fire being rapidly 
extinguished. However, engine(s) embedded in the fuselage or in pylons 
on the aft fuselage do not allow the pilot to see a fire.
    Isolating designated fire zones, through flammable fluid shutoff 
valves and firewalls, provides for containment of a fire. Containing 
fires ensures that components of the engine control system function 
effectively to permit a safe shutdown of the engine. We have only 
required a demonstration of containment for 15 minutes. If a fire 
occurs in a traditional part 23 airplane, the corrective action is to 
land as soon as possible. For a small, simple airplane originally 
envisioned by part 23, it is possible to descend the airplane to a 
suitable landing site within 15 minutes. If the isolation means do not 
extinguish the fire, the occupants can safely exit the airplane before 
the fire breaches the firewall.
    Simple and traditional airplanes normally have the engine located 
away from critical flight control systems and the primary structure. 
This location has ensured that throughout the fire event, the pilot can 
continue safe flight and control of the airplane and predict the 
effects of a fire. Other design features of simple and traditional 
airplanes (e.g., low stall speeds and short landing distances) ensure 
that even if an off-field landing occurs, the potential for a 
catastrophic outcome is minimized.
    Specifically for airplanes equipped with embedded engines, the 
consequences of a fire in an engine embedded in the fuselage are more 
varied, adverse, and difficult to predict than the engine fire for a 
typical part 23 airplane. Engine(s) embedded in the fuselage offer 
minimal opportunity to actually see a fire. The ability to extinguish 
an engine fire becomes extremely critical due to this location. With 
the engine(s) embedded in the fuselage, an engine fire could affect 
both the airplane's fuselage and the empennage structure, which 
includes the pitch and yaw controls. A sustained fire could result in 
damage to this primary structure and loss of airplane control before a 
pilot could make an emergency landing. For embedded engine 
installations, we also propose requiring a two-shot fire-extinguishing 
system because the metallic components

[[Page 41528]]

in the fire zone can become hot enough to reignite flammable fumes 
after someone extinguishes the first fire.
    We propose to upgrade flammability standards for thermal and 
acoustic insulation materials used in part 23 airplanes. The current 
standards do not realistically address situations where thermal or 
acoustic insulation materials may contribute to propagating a fire. The 
changes we propose are based on the requirements in Sec.  25.856(a), 
which were adopted following accidents involving part 25 airplanes, 
such as the Swissair MD-11. We believe the proposed standards would 
enhance safety by reducing the incidence and severity of cabin fires, 
particularly those in inaccessible areas where thermal and acoustic 
insulation materials are installed.
    The proposed standards include new flammability tests and criteria 
that address flame propagation, which would apply to thermal/acoustic 
insulation material installed in the fuselage of part 23 airplanes. 
Certification tests would consist of samples of thermal/acoustic 
insulation that would be exposed to a radiant heat source and a propane 
burner flame for 15 seconds. The insulation must not propagate flame 
more than 2 inches away from the burner. The flame time after removal 
of the burner must not exceed 3 seconds on any specimen. (See proposed 
Part II, Appendix F to part 23 for more details.)
    Current flammability requirements focus almost exclusively on 
materials located in occupied compartments (Sec.  23.853) and cargo 
compartments (Sec.  23.855). The potential for an in-flight fire is not 
limited to those specific compartments. Thermal/acoustic insulation can 
be installed throughout the fuselage in other areas, such as 
electrical/electronic compartments or surrounding air ducts, where the 
potential also exists for materials to spread fire. Proposed Sec.  
23.856 accounts for insulation installed within a specific compartment 
in areas the regulations might not otherwise cover. Proposed Sec.  
23.856 would be applicable to all part 23 airplanes, regardless of size 
or passenger capacity. Advisory material describing test sample 
configurations to address design details (e.g., tapes and hook-and-loop 
fasteners) is available in DOT/FAA/AR-00/12, Aircraft Materials Fire 
Test Handbook, dated April 2000. A copy of the handbook has been placed 
in the docket for this rulemaking.
    Insulation is usually constructed in what is commonly referred to 
as a ``blanket.'' Insulation blankets typically consist of two things: 
(1) A batting of a material generically referred to as fiberglass 
(i.e., glass fiber or glass wool), and (2) a film covering to contain 
the batting and to resist moisture penetration, usually metalized or 
non-metalized polyethylene terephthalate (PET), or metalized polyvinyl 
fluoride (PVF). Polyimide, a heat-resistant fiber used in insulation 
and adhesive, is another film used on certain airplanes. Regardless of 
the film type used, there are variations associated with its assembly 
for manufacture that result in performance differences from a fire 
safety standpoint. These variations include the density of the film, 
the type and fineness of the scrim bonded to the film, and the adhesive 
used to bond the scrim to the film. The scrim resembles a screen, and 
the mesh can vary in fineness. The scrim is usually constructed of 
either nylon or polyester and is bonded to the backside of the film to 
add shape and strength to the surface area. The adhesive used to bond 
the scrim to the film also varies. However, the type of adhesive used 
is important because fire retardant is frequently concentrated in the 
adhesive of the assembled sheet.

6. Powerplant and Operational Considerations

    Current Sec.  23.777 standardizes the height and location of 
powerplant controls because pilots may become confused and use the 
wrong controls on propeller-driven airplanes. This requirement, 
however, does not include single-power levers (which are typical for 
electronically-controlled engines). The FAA currently makes an ELOS 
finding for each airplane program that includes a single-power lever. 
We propose to revise paragraph (d) in Sec.  23.777 to incorporate the 
ELOS language.
    We propose to revise Sec.  23.903, paragraph (b)(2), to add 
requirements for fuselage-embedded, turbofan engine installations. 
These types of engine installations may have a negative impact on 
passenger safety because passengers occupy an area directly ahead of 
the turbojet engine fan disk. Certain turbofan engine designs have 
failure conditions that allow the fan disk to exit the front of the 
engine. This failure condition occurs if engines have bearing/shaft 
configurations that would allow the disk to separate from the engine 
and travel forward. If the engine has demonstrated this failure mode or 
if an analysis shows such a failure is conceivable, then the 
requirements of this section would apply. This requirement would be 
applicable to engines embedded in the airplane's fuselage where it 
could move forward into areas occupied by passengers or crew when a 
disk fails.
    In addition to the changes described above, we also propose 
requiring that electronic engine control systems meet the equipment, 
systems, and installation standards of Sec.  23.1309. We have applied 
this requirement to all digital engine controls in part 23 airplanes by 
special condition. The proposed rule change for Sec.  23.1141 would 
largely eliminate the need to issue special conditions on future 
certification programs.
    The ARC believed few single-engine airplane manufacturers have 
analyzed the criticality of their control system to meet the 
requirements of this proposed rule. The fundamental rule change 
recommended by the ARC for Sec.  23.1141 was not intended to invalidate 
or overrule the 14 CFR part 33 certification requirements. The proposed 
change for Sec.  23.1141 is intended for consideration of the airframe/
engine interface and how that interface protects against high intensity 
radiated fields (HIRF) and lightning.
    Over the years, airplane engines, including turbines, generated 
their own ignition system electrical power separate from the airplane's 
electrical generation system. Even with a complete electrical failure 
of the primary electrical systems, the engines would still run and be 
fully functional. However, all new engines are not designed with self-
electrical-generation capability. Some new engines rely on the 
airplane's electrical system to continue running and to be fully 
functional. Revising Sec.  23.1165(f) would ensure that when approved 
engines are installed on part 23 airframes, the engine ignition system 
is identified as an essential load. This would ensure that those 
engines have power during emergencies.\4\
---------------------------------------------------------------------------

    \4\ Under the proposed changes, we would certificate new 
engines, which include electronic ignition systems and engines with 
electronic controls necessary for the engine's operation, through 
the Engine and Propeller Directorate.
---------------------------------------------------------------------------

7. Avionics, Systems, and Equipment Changes

    Updated system requirements should reduce the regulatory burden on 
the applicant by clarifying and expanding the applicability of 
Sec. Sec.  23.1301 and 23.1309 to specific systems and functions. Most 
new part 23 airplane manufacturers are installing electronic primary 
flight displays (PFD) and multifunction displays (MFD) that replace 
conventional electromechanical and mechanical instruments. These new 
systems also offer more capability, reliability, and features that 
improve safety.

[[Page 41529]]

    We propose changes that would address displays, software, hardware, 
and power requirements. Besides advanced avionics and integrated 
systems, we propose to update the certification requirements to 
consider other advanced technologies (e.g., digital engine controls). 
We intend to apply lessons learned from recent small turbojet 
certification programs to update requirements for intended function and 
system safety.
    The ARC did not make a specific recommendation for Sec.  23.1301. 
However, the FAA seeks to clarify the intent of this section because it 
is frequently misinterpreted and misapplied. Clarifying the intent of 
Sec.  23.1301 would improve standardization for systems and equipment 
certification, particularly for non-required equipment and non-
essential functions embedded within complex avionic systems. Our intent 
is for the applicant to define proper functionality and to propose a 
means of compliance acceptable to the Administrator. We expect 
applicants to coordinate or negotiate deviations from established means 
of compliance with the Administrator as early as possible to minimize 
delay to project schedules.
    We propose to remove Sec.  23.1301(d), which currently states that 
equipment must ``function properly when installed.'' The proposed 
change would limit the scope of the rule since it would apply only to 
equipment required for type certification or operation. We propose a 
related change to clarify similar language in Sec.  23.1309 for proper 
functionality of installed equipment.
    The ARC did not make a specific recommendation for Sec.  23.1303. 
However, the FAA seeks to clarify the intent of this rule to 
accommodate new technology and eliminate the need to issue an ELOS for 
part 23 airplanes. We propose to amend Sec.  23.1303(c) by changing the 
current requirement from ``A direction indicator (non-stabilized 
magnetic compass)'' to ``A magnetic direction indicator.'' Section 
23.1303 does not include a direction indicator, other than the typical 
non-stabilized compass for part 23 airplanes. As new technology becomes 
more affordable for part 23 airplanes, many electronic flight 
instrument systems will use magnetically stabilized direction 
indicators (or electric compass systems) to measure and indicate the 
airplane heading to provide better performance.
    Current regulations require powerplant displays, referred to as 
``indicators'' in Sec.  23.1305, to provide trend or rate-of-change 
information. Advisory Circular (AC) 23.1311-1B, Installation of 
Electronic Displays in Part 23 Airplanes, dated June 14, 2005, 
currently provides a basis for an ELOS finding for digital engine 
display parameters.\5\ The proposed rule changes to Sec. Sec.  23.1303, 
23.1305, and 23.1311 would largely eliminate the need to issue ELOS 
findings for these systems and help standardize certification of new 
technology.
---------------------------------------------------------------------------

    \5\ A copy of the advisory circular is available on the Internet 
at http://www.faa.gov/regulations_policies/.
---------------------------------------------------------------------------

    The ARC also did not make a specific recommendation for Sec.  
23.1307. However, the FAA seeks to clarify language so applicants 
understand they may need additional equipment to operate their 
airplane. Part 23 is a minimum performance standard, and it may not 
include all the required equipment for commercial operations under 14 
CFR part 135. We propose to include parts 91 and 135 operations as 
examples to use when deciding which equipment is necessary for an 
airplane to operate at the maximum altitude.
a. System SafetyAssessment Requirements
    We originally designed the system safety assessment requirements of 
Sec.  23.1309 to address certification of electronic systems driven by 
microprocessors and other complex systems. However, the requirements of 
Sec.  23.1309 are being applied to conventional mechanical and 
electromechanical systems with well-established design and 
certification processes. This was not our intent, and we propose to 
revise Sec.  23.1309 to clarify the intended application of the rule.
    Proposed changes for Sec.  23.1309 also clarify the intent for 
certification of electronic engine controls. The current section 
excludes systems certificated with the engine. Therefore, we use 
special conditions for all electronic engine control installation 
approvals to capture the evaluation requirements of Sec.  23.1309. We 
applied special conditions to the interface of the electronic engine 
control system and the airplane. We also applied special conditions to 
verify that the installation does not invalidate the assumptions made 
during part 33 certification of the engine. This proposal would address 
electronic engine controls and eliminate the need for special 
conditions to apply Sec.  23.1309 to electronic engine control systems.
    Proposed Sec.  23.1309(a) would have requirements for two different 
types of equipment and systems installed in the airplane. Proposed 
Sec.  23.1309(a)(1) would cover the equipment and systems that have no 
negative safety effect and those installed to meet a regulatory 
requirement. Such systems and equipment are required to ``perform as 
intended under the airplane operating and environmental conditions.'' 
Proposed Sec.  23.1309(a)(2) would require the applicant to show that 
all equipment and systems (including approved ``amenities,'' such as a 
coffee pot and entertainment systems) have no safety effect on the 
operation of the airplane. The phrase ``improper functioning'' 
identifies equipment and system failures that have a potentially 
negative effect on airplane safety. Therefore, we must consider their 
potential failure condition(s). Using Sec.  23.1309, we must analyze 
any installed equipment or system that has potential failure 
condition(s) that are catastrophic, hazardous, major, or minor to 
determine their impact on the safe operation of the airplane.
    We propose to clarify the certification requirements, environmental 
qualification test requirements, and our intent for determining proper 
``intended function'' of non-required systems and equipment that do not 
have a safety effect on the airplane. A problem with the current 
requirements for airplane manufacturers arises when certification 
authorities question installation of non-required systems and equipment 
that do not perform following their specifications and, therefore, are 
``not functioning properly when installed.'' Usually, normal 
installation practices can be based on a relatively simple qualitative 
installation evaluation. If the possible safety impacts (including 
failure modes or effects) are questionable, or isolation between 
systems is provided by complex means, more formal structured evaluation 
methods or a design change may be necessary. We do not require these 
types of equipment and systems to function properly when installed. 
However, we would require them to function when they are tested to 
verify that they do not interfere with the operation of other airplane 
equipment and systems and do not pose a hazard in and of themselves.
    Also under proposed changes to Sec.  23.1309(a), we would replace 
the conditional qualifiers of ``under any foreseeable operating 
condition,'' contained in the current Sec.  23.1309(b)(1), with ``under 
the airplane operating and environmental conditions.'' Our intent with 
this proposal is for the applicant to take two actions. First, the 
applicant must consider the full normal operating envelope of the 
airplane, as defined by the airplane flight manual (AFM), with any 
modification to that envelope associated with abnormal or emergency 
procedures and any anticipated crew

[[Page 41530]]

action. Second, the applicant must consider the anticipated external 
and internal airplane environmental conditions, as well as any 
additional conditions where equipment and systems are assumed to 
``perform as intended.'' We propose to make this change in response to 
an observation that although certain operating conditions are 
foreseeable, achieving normal performance when they exist is not always 
possible (e.g., you may foresee ash clouds from volcanic eruptions, but 
airplanes with current technology cannot safely fly in such clouds).
    The FAA currently accepts equipment that is susceptible to failures 
if these failures do not contribute significantly to the existing risks 
(e.g., some degradation in functionality and capability is routinely 
allowed during some environmental qualifications, such as HIRF and 
lightning testing). System lightning protection specifically allows the 
loss of function and capability of some electrical/electronic systems 
when the airplane is exposed to lightning, if ``these functions can be 
recovered in a timely manner.''
    Proposed Sec.  23.1309(a)(3) is applicable for all functional 
reliability, flight testing, or flight evaluations. This proposed 
change clarifies the FAA's expectations for functional testing during 
certification of complex systems, but it is not meant to increase the 
testing burden on the applicant. The FAA's intent is to prohibit 
certification of systems with known defects in required functions that 
could impact safety. For example, it would not be acceptable for an 
integrated avionics system to be approved until known functional 
defects in required functions are corrected. The system would not be 
allowed to exhibit unintended or improper functionality for flight 
critical functions. The rate of occurrence of failures, malfunctions, 
and design errors must be appropriate for the failure condition(s) of 
the type of system and airplane.
    Proposed Sec.  23.1309(b) would codify a long-established means of 
compliance with current Sec.  23.1309(b) and update failure 
condition(s) terminology used in related system safety assessment 
documents developed by industry working groups (e.g., RTCA and the 
Society of Automotive Engineers (SAE)). This means of compliance 
identifies four classes of airplanes as defined in Appendix K of this 
proposal and applies appropriate probability values and development 
assurance levels for each class. The original text of Sec.  
23.1309(b)(4) has been retained and appears as Sec.  23.1309(b)(5) in 
this revision. The proposed changes to Sec.  23.1309(c) and (d) are 
meant to define the proper scope and intent for applying Sec.  23.1309 
depth of analysis for system safety assessments to all systems.
    With proposed Sec.  23.1309(f), we would make Sec.  23.1309 
compatible with the current Sec.  23.1322 (``Warning, caution, and 
advisory lights'') that distinguishes between caution, warning, and 
advisory lights installed on the flight deck. Rather than only 
providing a warning to the flight crew, which is required by the 
current rule, proposed Sec.  23.1309(f) would require that information 
concerning an unsafe system operating condition(s) be provided to the 
flight crew.
    A warning indication would still be required if immediate action by 
a flight crewmember were required. The particular method of indication 
would depend on the urgency and need for flight crew awareness or 
action that is necessary for the particular failure. Inherent airplane 
characteristics may be used in lieu of dedicated indications and 
annunciations that can be shown to be timely and effective. The use of 
periodic maintenance or flight crew checks to detect significant latent 
failures when they occur should not be used in lieu of practical and 
reliable failure monitoring and indications.
    Proposed Sec.  23.1309(f) would clarify the current rule by 
specifying that the design of systems and controls, including 
indications and annunciations, must reduce crew errors that could 
create more hazards. The additional hazards to be minimized would be 
those that are caused by inappropriate actions made by a crewmember in 
response to the failure, or those that could occur after a failure. Any 
procedures for the flight crew to follow after the occurrence of a 
failure indication or annunciation would be described in the approved 
Airplane Flight Manual (AFM), AFM revision, or AFM supplement, unless 
they are accepted as part of normal aviation abilities.
    Current Sec.  23.1309 (c) and (d) are not directly related to the 
other safety and analysis requirements of Sec.  23.1309. The ARC 
considered it appropriate to state the requirements separately for 
clarity. We agree with this suggested change and propose to add a new 
Sec.  23.1310 to accommodate the change. The requirements as originally 
stated in current Sec.  23.1309 would not change, except for a new 
section number.
    We propose several changes to Sec.  23.1311(a)(5) for plain 
language purposes. In proposed Sec.  23.1311(a)(5), we replace the 
phrase ``individual electronic display indicators'' with ``electronic 
display parameters.'' The term ``indicator'' has a long-standing 
definition based on conventional, mechanical indicators; therefore, the 
term has caused confusion. These electronic display parameters could be 
integrated on one electronic display that is independent of the primary 
flight display. In proposed Sec.  23.1311(a)(6), we add the phrase 
``that provide a quick-glance sense of rate and, when appropriate, 
trend information'' to clarify ``sensory cues.''
    We propose to add the term ``when appropriate'' to eliminate the 
requirement to display trend information when it would otherwise 
provide intuitive information to the pilot. For example, the trend for 
fuel burn is always negative. We propose to remove the remainder of 
section (a)(6), ``* * * that are equivalent to those in the instrument 
being replaced by the electronic display indicator'' to prevent 
confusion since most instruments will be electronic. In proposed Sec.  
23.1311(a)(7), we have added the word ``equivalent'' to make acceptable 
instrument markings on electronic displays that are equivalent to those 
instrument markings on conventional mechanical and electromechanical 
instruments.
    In proposed Sec.  23.1311(b), we replace the phrase ``remain 
available to the crew, without need for immediate action'' with ``be 
available within one second to the crew with a single pilot action or 
by automatic means.'' The proposed language allows an applicant to take 
credit for reversionary or secondary flight displays on a multi-
function flight display (MFD) that provides a secondary means of 
primary flight information (PFI). This is acceptable if the display can 
``be available within one second to the crew with a single pilot action 
or by automatic means.'' MFD's may also display PFI as needed to ensure 
continuity of operations. The display of PFI on reversionary 
(secondary) displays must be arranged in the basic T-configuration. 
Also, such displays must be legible and usable from the pilot's 
position with minimal head movement to meet the requirements of Sec.  
23.1321.
    There are three acceptable methods for meeting the requirements of 
Sec.  23.1311(b)--(1) Dedicated standby instruments, (2) dual primary 
flight displays (PFDs), or (3) reversionary displays that display 
independent attitude. The standby instruments, or another independent 
PFD, would ensure that primary flight information is available to the 
pilot during all phases of flight and system failures. The

[[Page 41531]]

electronic display systems with dual PFDs should incorporate dual, 
independently-powered sensors that would provide primary flight 
parameters (e.g., attitude heading reference system (AHRS) with 
comparators and dual air data computer (ADC)). A reversionary 
configuration would have a single pilot action that would force MFD 
displays into reversionary mode operation by a single pilot action 
within one second or less. However, the PFI must be displayed in 
substantially the same format and size in the reversionary mode as it 
is in normal mode. The single pilot action should be easily recognized, 
readily accessible, and have the control within the pilot's primary 
field of view.
    The reversionary method could include an automatic reversionary 
display with a single pilot action. If PFI on another display is not 
provided, we would require automatic switching to ensure PFI is 
available to the pilot. This automatic reversionary capability would 
cover most possible malfunctions. While a total loss of the display may 
not be reliably detected automatically, such a failure condition would 
be obvious to the pilot. Malfunctions that result in automatic 
switching would be extensive enough to ensure PFI is available at the 
reliability level required by Sec.  23.1309. If such a malfunction 
occurs, a single pilot action would provide a full display of the 
essential information on the remaining display within one second. All 
modes, sources, frequencies, and flight plan data would be exactly as 
they were on the PFD before the failure.
    Another reversionary method would include a means to access the 
reversionary mode manually through a single pilot action. Manual 
activation of the reversionary mode on the MFD through single action by 
the pilot would be acceptable when procedures to activate the PFI are 
accomplished before entering critical phases of flight. The PFI would 
display continuously on the reversionary display during critical phases 
of flight (e.g., takeoff, landing, and missed or final approach).
    To meet the proposed turbojet performance requirements in subpart 
B, the pilot would need accurate speed indicators while accelerating on 
the runway. We propose to revise Sec.  23.1323(e) to add the 
requirement to calibrate the airspeed system down to 0.8 of the minimum 
value of V1. Also, we propose to adopt the language used in 
part 25 for this same requirement because it is more in line with 
operating new part 23 turbojets.
    The proposed changes to Sec.  23.1331 would apply to instruments 
that rely on a power source to provide required flight information for 
instrument flight rules (IFR) operations. Consequently, this section 
would apply to all flight instruments, such as those required by parts 
23, 91, 121, and 135. Airplanes limited by type design to visual flight 
rules (VFR) operations would not have to comply with the requirements 
of proposed Sec.  23.1331(c).
    Each independent power source must provide sufficient power for 
normal operations throughout the approved flight envelope of the 
airplane and for any operations approved for the airplane. Section 
23.1331(c) would not require the installation of dual alternators or 
vacuum systems on single-engine airplanes. One option would include a 
dedicated battery that meets the requirements of Sec.  23.1353(h) for 
electrical instrument loads essential to continued safe flight and 
landing. Another option would include separately powered instruments 
for primary and standby use. The last option would include performing a 
system safety analysis, per Sec.  23.1309, to identify the procedures 
necessary to verify the charge state of any airplane starting battery 
that is used to power a stand-by system.
    The ARC did not make a specific recommendation for Sec.  23.1353. 
However, we propose to add additional battery endurance requirements 
depending on the airplane's altitude performance. Proposed Sec.  
23.1353 addresses the power needs of new all-electrical instruments, 
navigation and communications equipment, and engine controls.
    When Sec.  23.1353(h) was adopted, part 23 airplanes were mostly 
mechanical. We did not envision all-electric, or almost all-electric, 
airplanes. Current Sec.  23.1353(h) requires 30 minutes of sufficient 
electrical power for a reduced or emergency group of equipment and 
instrumentation. We considered 30 minutes adequate to reach VFR 
conditions to continue flying to an adequate airport and to accomplish 
a safe landing for traditional part 23 airplanes. We did not envision 
integrated electric cockpits when we developed Sec.  23.1353(h). New 
part 23 airplanes are being certificated with all-electrical 
instruments, including the standby instruments. This reliance on 
electric power increases the importance of ensuring adequate battery 
power until the pilot can descend and make a safe landing.
    Most new engines utilize electronic engine controls. These engine 
controls may rely on the airplane's electrical system for power and to 
control fuel and ignition. Large engines typically installed on part 25 
airplanes have a dedicated power source running off the engine; as long 
as the engine is running, the electronic engine control has power. Some 
of the smaller, simpler engines emerging in part 23 airplanes may not 
have these dedicated power sources and may rely on the airplane's 
electrical system to keep functioning.
    We believe that most new turbine-powered airplanes, and some 
turbocharged, piston-powered airplanes, will operate at high altitudes 
under IFR. Under these conditions, 30 minutes may not be adequate for 
battery power because of the time it would take to descend from maximum 
altitude to find visual meteorological conditions (VMC) and land, or to 
perform an instrument approach for a landing. For these reasons, 
proposed Sec.  23.1353(h) would extend the battery time requirement to 
60 minutes for airplanes approved with a maximum altitude above 25,000 
feet.
    Many new single-engine airplanes are intended for use in part 135 
passenger service. Proposed Sec.  23.1353(h) provides consistency with 
the operating requirements for single-engine IFR in Sec.  135.163(i). 
That section requires a 60-minute battery to power all emergency 
equipment, as specified by the manufacturer, to allow continued safe 
flight and landing.
b. Allowable Qualitative Failure Condition Probabilities
    We propose to add Appendix K to show the appropriate airplane 
systems probability standards, failure conditions, and related 
development assurance for four certification classes of airplanes 
designed to part 23 standards. Proposed Appendix K includes development 
assurance levels that correlate to the software levels in RTCA/DO-178B 
and the complex design assurance levels in RTCA/DO-254. We provided 
quantitative values in Appendix K to indicate the order of probability 
range for each certification class and failure condition.
    As used in Sec.  23.1309, the FAA proposes the following 
definitions for terms used in Appendix K:
    i. Extremely remote failure conditions: Those failure conditions 
not anticipated to occur to each airplane during its total life but 
which may occur a few times when considering the total operational life 
of all airplanes of this type. For quantitative assessments, refer to 
the probability values shown for hazardous failure conditions in 
Appendix K.
    ii. Extremely improbable failure conditions: For commuter category 
airplanes, those failure conditions so unlikely that they are not 
anticipated to occur during the entire operational life of all 
airplanes of one type. For other

[[Page 41532]]

classes of airplanes, the likelihood of occurrence may be greater. For 
quantitative assessments, refer to the probability values shown for 
catastrophic failure conditions in Appendix K.
    iii. Probable failure conditions: Those failure conditions 
anticipated to occur one or more times during the entire operational 
life of each airplane. These failure conditions may be determined on 
the basis of past service experience with similar components in 
comparable airplane applications. For quantitative assessments, refer 
to the probability values shown for minor failure conditions in 
Appendix K.
    iv. Remote failure conditions: Those failure conditions that are 
unlikely to occur to each airplane during its total life but that may 
occur several times when considering the total operational life of a 
number of airplanes of this type. For quantitative assessments, refer 
to the probability values shown for major failure conditions in 
Appendix K.
    v. Design appraisal: A qualitative appraisal of the integrity and 
safety of the system design. An effective appraisal requires 
experienced judgment.
    vi. Development assurance level: All planned and systematic actions 
used to substantiate, to an adequate level of confidence, that errors 
in requirements, design, and implementation have been identified and 
corrected such that the system satisfies the applicable certification 
basis. (The development assurance levels in Appendix K are intended to 
correlate to software levels in RTCA/DO-178B and complex hardware 
design assurance levels in RTCA/DO-254 for the system or item.)
    vii. Simple and conventional systems: A system is considered 
``simple'' or ``conventional'' if its function, the technological means 
to implement its function, and its intended usage are all the same as, 
or closely similar to, that of previously approved systems commonly 
used. The systems that have established an adequate service history and 
the means of compliance for approval are generally accepted as 
``simple'' or ``conventional.'' Simple systems do not contain software 
or complex hardware requiring compliance by documents. These documents 
are the developmental assurance levels assigned in RTCA/DO-178A/B, 
Software Considerations in Airborne Systems and Equipment 
Certification, or RTCA/DO-254, Design Assurance Guidance for Airborne 
Electronic Hardware documents or later versions.
    For simple and conventional installations, it may be possible to 
assess a hazardous or catastrophic failure condition(s) as being 
extremely remote or extremely improbable, respectively, based on an FAA 
approved qualitative analysis. The basis for the assessment would be 
the degree of redundancy, the established independence and isolation of 
the channels, and the reliability record of the technology involved. 
Satisfactory service experience on similar systems commonly used in 
many airplanes may be sufficient when a close similarity is established 
regarding both the system design and operating conditions.
    viii. Installation appraisal: A qualitative appraisal of the 
integrity and safety of the installation. Any deviations from normal 
industry-accepted installation practices should be evaluated.

8. Placards, Speeds, Operating Limitations, and Information

    Currently, Sec.  23.853(d)(2) requires placards for commuter 
category airplanes to have red letters at least \1/2\ inch high on a 
white background at least 1 inch high. The letter size is not a 
requirement for the part 23 normal category or for the part 25 
transport category airplanes. We propose removing the letter size 
requirement from this section. We also propose removing the ashtray 
requirement from this section since smoking is no longer allowed in 
parts 121 and 135 operations. We propose to amend paragraph (d)(2) of 
this section to read ``Lavatories must have `No Smoking' or `No Smoking 
in Lavatory' placards located conspicuously on each side of the entry 
door.''
    Proposed Sec.  23.629 would allow the use of VDF in 
place of VD for flight testing turbojets. In addition, the 
proposed amendment for Sec.  23.1505 would require airspeed limits 
based on a combination of analytical (VD/MD) and 
demonstrated (VDF/MDF) dive speeds for turbojets. 
Proposed Sec.  23.1505(c) would include specific turbojet speed 
designations.
    The ARC did not make a specific recommendation regarding Sec.  
23.1525. However, we propose to clarify language so applicants 
understand that additional equipment may be needed to operate their 
airplane. Part 23 is a minimum performance standard, and it may not 
include all the required equipment for operations under part 135. We 
propose to include parts 91 and 135 operations as examples of the kinds 
of operation authorized.
    Proposed Sec.  23.1545 limits the white flap arc to reciprocating 
engine airplanes. This change reflects standard practice for turbojets 
and is included in all part 23 turbojet special conditions.
    Proposed Sec.  23.1555(d)(3) would require fuel systems with a 
calibrated fuel quantity indication system to comply with Sec.  
23.1337(b)(1) while removing current placard requirements. Most modern 
turbine-powered airplanes have a calibrated fuel quantity indicating 
system that is density compensated and accurately indicates the actual 
usable fuel quantity in each tank. When using these types of fuel 
indicating systems, we consider the placards required by Sec. Sec.  
23.1555(d)(1) and (2) redundant. The placards or markings required by 
Sec. Sec.  23.1555(d)(1) and (2) indicate the maximum capacity of the 
tank. For these reasons, we propose to remove the placard requirement 
for these accurate fuel quantity indicating systems.
    The placard requirements of Sec. Sec.  23.1559, 23.1563 and 23.1567 
have been a source of confusion to both FAA and industry personnel 
relative to placard lighting. We are proposing changes to these three 
rules to clarify the intent of these requirements. The requirements 
specified on the placard in Sec.  23.1559 are relative to preflight 
planning, and this placard is not normally referenced in flight. As 
long as the placard is ``in clear view of the pilot'' and the pilot can 
view it at night using a flashlight or other means, the intent of the 
rule is met. The requirement has been confusing for certification 
offices and this proposal makes the placard lighting intent clear. We 
propose to add a new paragraph Sec.  23.1559(d), which states ``The 
placard required by this section need not be lighted.''
    With modern flight display equipment, the necessary information may 
now be available on that equipment and is automatically illuminated as 
part of the display. Therefore, we also propose to update Sec.  23.1563 
to clarify requirements for night lighting of the placard. Maneuvering 
speed is applicable to operations that may involve intentional large 
control input and is therefore not applicable to normal night 
operations. Most modern airplanes have means for the landing gear speed 
to be displayed in the airspeed indicator or on lighted portions of the 
landing gear control. They have the means for the airspeed indicator to 
display low speed awareness or other airspeed reference information to 
provide safety above VMC. Lighting this placard is 
unnecessary for safety and provides another source of unwanted lighting 
reflections in the cockpit.
    The requirements specified in Sec.  23.1567 for the limitation 
placard relate to acrobatic maneuvers and spin information related to 
preflight

[[Page 41533]]

planning. Since these maneuvers are not normally conducted during night 
operations, the placard information is not required for night flight. 
If the placard is ``in clear view of the pilot'' and the pilot can view 
the placard at night using a flashlight or other means, it meets the 
intent of the rule. The proposed change to Sec.  23.1567 clarifies our 
intent of this rule relative to lighting.
    We propose to incorporate the existing special conditions into the 
AFM requirements in Sec. Sec.  23.1583, 23.1585, and 23.1587. These are 
necessary to be consistent with the performance requirements proposed 
in subpart B. These requirements include the ARC recommended, single-
engine climb performance increase for turboprops.

III. Regulatory Notices and Analyses

Paperwork Reduction Act

    According to the 1995 amendments to the Paperwork Reduction Act (5 
CFR 1320.8(b)(2)(vi)), an agency may not collect or sponsor the 
collection of information, nor may it impose an information collection 
requirement 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 the Office of Management and 
Budget approval.

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 
reviewed the corresponding ICAO Standards and Recommended Practices and 
has identified no differences with these proposed regulations.

Regulatory Evaluation, Regulatory Flexibility Determination, 
International 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 
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 (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 requires agencies to consider international 
standards and, where appropriate, that they 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 with base year of 
1995). This portion of the preamble summarizes the FAA's analysis of 
the economic impacts of this proposed rule. We suggest readers seeking 
greater detail read the full regulatory evaluation, a copy of which we 
have placed in the docket for this rulemaking.
    In conducting these analyses, FAA has determined that this proposed 
rule: (1) Has benefits that justify its costs, (2) is not an 
economically ``significant regulatory action'' as defined in section 
3(f) of Executive Order 12866, (3) the Office of Management and Budget 
has determined this proposal is ``significant''; (4) would not have a 
significant economic impact on a substantial number of small entities; 
(5) would not create unnecessary obstacles to the foreign commerce of 
the United States; and (6) would not impose an unfunded mandate on 
state, local, or tribal governments, or on the private sector by 
exceeding the threshold identified above. These analyses are summarized 
below.
Total Benefits and Costs of This Rule
    The estimated base case cost of this proposed rule is about 
$472,000 ($443,000 in 7 percent present value terms). The estimated 
safety benefits would be to avoid 14 accidents and are valued at about 
$82.7 million. The estimated base case efficiency benefits to 
streamline the part 23 certification process are valued at about $1.6 
million. The total base case benefit is equal to the sum of the safety 
and efficiency benefits and is valued at about $84.2 million.
Who Is Potentially Affected by This Rule
    This proposed rulemaking will affect manufacturers and operators of 
part 23 reciprocal engine, turboprop and turbojet airplanes.

Assumptions

    The proposed rule makes the following assumptions:
    1. The base year is 2008.
    2. The average retirement age of a U.S. operated part 23 airplane 
is 32 years.
    3. The average part 23 airplane production life cycle is 24 years.
    4. The analysis period extends for 56 (32 + 24) years.
    5. U.S companies would manufacture 75 percent of the turbojets 
forecasted by the FAA.
    6. All business and commercial part 23 airplanes would operate in 
commuter service.
    7. The value of a fatality avoided is $5.8 million.

Benefits of This Rule

    For part 23 airplanes, we estimated that the proposed changes would 
avoid about 14 accidents over the 24-year operating lives of 37,657 
new-production airplanes. The resulting benefits include averted 
fatalities and injuries, loss of airplanes, investigation cost, and 
collateral damages for the accidents. The safety benefits for averting 
the 14 accidents are about $82.7 million ($17.8 million in 7 percent 
present value terms).
    Other benefits of this proposal include FAA and industry paperwork 
and certification time saved by standardizing and streamlining the 
certification of part 23 airplanes. The base case efficiency benefits 
for standardizing and streamlining the certification process is valued 
at $1.6 million.
    The total base case benefit is equal to the sum of the safety and 
efficiency benefits and is about $84.2 million ($19.3 million in 7 
percent present value terms).

Costs of This Rule

    Constant-dollar (2008$) unit costs per aircraft by 14 CFR Part 23 
could be as high as: $165 for turboprop airplanes and $6,550 for 
turbojet airplanes. Total incremental costs equal the constant-dollar 
unit costs multiplied by the number of aircraft produced over 10 years. 
The base case costs of this rule are about $472,000 ($443,000 in 7 
percent present value terms) and the high case costs of this rule are 
about $11.1 million ($5.0 million in 7 percent present value terms).

Alternatives Considered

    Alternative 1--The FAA would continue to issue special exemptions, 
exceptions and equivalent levels of safety to certificate part 23 
airplanes. As that would perpetuate ``rulemaking by exemption,'' we 
choose not to continue with the status quo.
    Alternative 2--The FAA continue to enforce the current regulations 
that affect single engine climb performance.

[[Page 41534]]

The FAA rejected this alternative because the accident rate on twin 
piston engine and turboprop airplanes identified a safety issue that 
had to be addressed.

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 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 impact on a substantial number of entities. The purpose of 
this analysis is to provide the reasoning underlying the FAA 
determination.
    First, we will discuss the reasons why the FAA is considering this 
action. We will follow with a discussion of the objective of, and legal 
basis for, the proposed rule. Next we explain there are no relevant 
federal rules which may overlap, duplicate, or conflict with the 
proposed rule. Lastly, we will describe and provide an estimate of the 
number of small entities affected by the proposed rule and why the FAA 
believes this proposed rule would not result in a significant economic 
impact on a substantial number of small entities.
    We now discuss the reasons why the FAA is considering this action.
    The FAA proposes this action to amend safety and applicability 
standards of the part 23 turbojet industry to reflect the current needs 
of the industry, accommodate future trends, address emerging 
technologies, and provide for future aircraft operations. This proposal 
primarily standardizes and streamlines the certification of part 23 
turbojet airplanes. The intent of the proposed changes to parts 1 and 
23 are necessary to eliminate the current workload of exemptions, 
special conditions, and equivalent levels of safety determinations 
necessary to certificate part 23 turbojets. These proposed part 23 
changes will also clarify areas of frequent non-standardization and 
misinterpretation and provide appropriate safety and applicability 
standards that reflect the current state of the industry, emerging 
technologies and new types of operations for all part 23 airplanes; 
including turbojet, turboprop and reciprocating engine airplanes.
    The FAA currently issues type certificates (TCs) for part 23 
turbojets using extensive special conditions. Issuance of TCs has not 
been significant until now because there were few part 23 turbojet 
programs. However, in the past five years, the number of new turbojet 
certification programs in part 23 has increased more than 100 percent 
over the past three decades.
    The need to incorporate these special conditions into part 23 stems 
from both the existing number of new jet programs and the expected 
future jet programs. Codifying these special conditions will allow 
manufacturers to know the requirements during their design phase 
instead of designing the turbojet and then having to apply for special 
conditions that may ultimately require a redesign. Codifying will also 
reduce the manufacturers and FAA's paper process required to TC an 
airplane and reduces the potential for program delays. These proposed 
changes would also clarify areas of frequent non-standardization and 
misinterpretation, particularly for electronic equipment and system 
certification.
    The revisions include general definitions, error correction, and 
specific requirements for performance and handling characteristics to 
ensure safe operation of part 23 transport category airplanes. The 
proposed revisions would apply to all future new part 23 turbojet, 
turboprop and reciprocating engine airplane certifications.
    We now discuss the legal basis for, and objective of, the proposed 
rule. Next, we discuss if there are relevant federal rules, which may 
overlap, duplicate, or conflict with the proposed rule.
    The FAA's authority to issue rules on 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. 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. This regulation is 
within the scope of that authority because it prescribes new safety 
standards for the design of part 23 normal, utility, acrobatic, and 
commuter category airplanes.
    Accordingly, this proposed rule will amend Title 14 of the Code of 
Federal Regulations to address deficiencies in current regulations 
regarding the certification of part 23 light jets, turboprops and 
reciprocating engine airplanes. The proposed rule would clarify areas 
of frequent non-standardization and misinterpretation and codify 
certification requirements that currently exist in special conditions.
    The FAA is unaware the proposed rule will overlap, duplicate, or 
conflict with existing Federal Rules.
    We now discuss our methodology to determine the number of small 
entities for which the proposed rule will apply.
    Under the RFA, the FAA must determine whether a proposed rule 
significantly affects a substantial number of small entities. This 
determination is typically based on small entity size and cost 
thresholds that vary depending on the affected industry.
    Using the size standards from the Small Business Administration for 
Air Transportation and Aircraft Manufacturing, we defined companies as 
small entities if they have fewer than 1,500 employees.\6\
---------------------------------------------------------------------------

    \6\ 13 CFR 121.201, Size Standards Used to Define Small Business 
Concerns, Sector 48-49 Transportation, Subsector 481 Air 
Transportation.
---------------------------------------------------------------------------

    There are 11 U.S. aircraft manufacturers currently producing part 
23 airplanes and could be affected by this proposal. These 
manufacturers are American Champion, Cessna, Cirrus, Eclipse, Hawker 
Beechcraft, Liberty, Maule, Mooney, Piper, Quest, and Sino Swearingen.
    Using information provided by the World Aviation Directory, 
Internet filings and industry contacts, manufacturers that are 
subsidiary

[[Page 41535]]

businesses of larger businesses, manufacturers that are foreign owned, 
and businesses with more than 1,500 employees were eliminated from the 
list of entities. Cessna and Hawker Beechcraft are businesses with more 
than 1,500 employees and Cirrus and Liberty are foreign owned. We found 
no source of employment or revenue data for American Champion. For the 
remaining businesses, we obtained company revenue and employment from 
the above sources.
    The base year for the proposed rule is 2008. Although the FAA 
forecasts traffic and air carrier fleets, we can not determine the 
number of new entrants nor who will be in business in the future. 
Therefore we use current U.S. manufacturer's revenue and employment in 
order to determine the number of operators this proposal would affect.
    The methodology discussed above resulted in the following six U.S. 
part 23 aircraft manufacturers, with less than 1,500 employees, shown 
in Table RF1.

                                Table RF1
------------------------------------------------------------------------
                Company                    Employees     Annual revenue
------------------------------------------------------------------------
Quest.................................              60        $4,600,000
Maule.................................              86         5,700,000
Piper.................................             100         7,600,000
Mooney................................             400        42,083,000
Sino Swearingen.......................             400        25,300,000
Eclipse...............................           1,000        36,700,000
------------------------------------------------------------------------

    The majority of this proposal affects the certification of 
turbojets and has a minor affect on the certification of turboprop and 
reciprocating engine airplanes by clarifying frequent non-
standardization and misinterpretations of the current part 23 rules.
    From the list of part 23 small entity U.S. airplane manufacturers 
above, only Eclipse and Sino Swearingen produce turbojet airplanes and 
Piper and Quest produce turboprop airplanes. The remaining part 23 
small entity U.S. airplane manufacturers produce reciprocating engine 
airplanes.
    In the regulatory evaluation, we estimated that operators of newly 
certificated part 23 airplanes would incur additional fuel costs. 
Additionally, operators could incur costs from added weight and a 
reduced payload capacity. The U.S. Census Bureau data on the Small 
Business Administration's Web site shows an estimate of the total 
number of small business entities who could be affected if they 
purchase newly certificated part 23 airplanes.\7\ The U.S. Census 
Bureau data lists 39,754 small entities in the Non-scheduled Air 
Transportation Industry that employ less than 500 employees. Many of 
these non-scheduled businesses are in part 25. Other small businesses 
may own aircraft and not be included in the U.S. Census Bureau Non-
scheduled Air Transportation Industry category. The estimate of the 
affect of this proposal on the total number of small entities that 
operate part 23 airplanes is developed below.
---------------------------------------------------------------------------

    \7\ http://www.sba.gov/advo/research/us05_n6.pdf.
---------------------------------------------------------------------------

    We now discuss our methodology to estimate the costs of this 
proposal to the small entities part 23 airplane manufacturers and 
operators. We will also discuss why the FAA believes this proposed rule 
would not result in a significant economic impact to part 23 airplane 
manufacturers and operators.
    In 2003, we published a notice (68 FR 5488) creating the part 125/
135 Aviation Rulemaking Committee (ARC). FAA and the part 23 industry 
have worked together to develop common certification part 23 airplane 
requirements proposed in this rulemaking. We contacted the part 23 
aircraft manufacturers, the ARC, and General Aviation Manufacturers 
Association (GAMA) (an industry association for part 23 aircraft 
manufacturers) for specific cost estimates for each proposed section 
change for this rule. Not every party we contacted responded to our 
request for costs. Many of the ARC members, from the domestic and 
international manufacturing community, collaborated and filed a joint 
cost estimate for this proposed rule. We are basing our cost estimates 
for this proposed rule from these part 23 U.S. aircraft manufacturers, 
ARC members and GAMA.
    The part 23 U.S. airplane manufacturers, ARC members, and industry 
association informed us that this proposed rulemaking would add 
manufacturer certification costs for fire extinguishing systems, climb, 
and take-off warning systems. Industry informed us that this proposal 
would save the manufacturers design time for the certification of 
cockpit controls. Industry has also informed us that every other 
proposed section of this rule is either clarifying, error correcting, 
or would only add minimal to no costs.
    The proposed rule adds certification requirements for the following 
part 23 airplane categories:
    1. All turbojet airplanes,
    2. All turbojet airplanes with a MTOW less than 6,000 pounds,
    3. All turboprop airplanes,
    4. All reciprocal engine airplanes, and
    5. All reciprocal twin engine airplanes with a MTOW greater than 
6,000 pounds.
    In some cases the proposed regulations only affect part 23 
airplanes operated in revenue service. Any part 23 airplane could be 
used as a business airplane to haul passengers and cargo in commercial 
service. We estimated the business versus personal use of a part 23 
airplane by analyzing the number of all US-operated airplanes from 
Table 3.1 of the 2006 General Aviation and Part 135 Activity Survey. 
Table 3.1 shows the breakout of the 2006 General Aviation fleet by 
business, corporate, instructional, aerial applications, aerial 
observations, aerial other, external load, other work, sight see, air 
medical, other, part 135 Air Taxi, Air Tours, and Air Medical airplane 
usage. For the purpose of estimating the cost of this proposal, we 
assume all business part 23 airplane operators from Table 3.1 of the 
2006 General Aviation and Part 135 Activity Survey would operate in 
Commuter service. Table RF2 shows these results.

[[Page 41536]]



                    Table RF2--2006 General Aviation and Part 135 Activity Survey--Table 3.1
----------------------------------------------------------------------------------------------------------------
                  Aircraft type                    Total active      Personal       % Personal      % Business
----------------------------------------------------------------------------------------------------------------
Piston..........................................         163,743         118,618           72.44           27.56
Turboprop.......................................           8,063           1,177           14.60           85.40
Turbojet........................................          10,379             750            7.23           92.77
----------------------------------------------------------------------------------------------------------------

    Table RF3 shows the results of the proposed sections that add (or 
subtract) incremental costs by increasing design or flight testing 
times, adds weight, or reducing payload.

                                                                                            Table RF3
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                     Certification        Flight Operation                            Part 23 Airplane Categories Affected
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                                                  Twin
                                                                                                                            Turbojet                           reciprocal
                                                                   Design     Flight   Additional    Payload                 <6,000                Reciprocal    engine
           Part 23 Section                   Section title         hours       test      weight     reduction   Turbojet       Turboprop    engine      >6,000           Category
                                                                              hours                                           MTOW                              
                                                                                                                                                                  MTOW
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
23.1193(g), 23.1195(a), 23.1197,       Cowling and Nacelle,      .........         50          25  ..........  ..........  ..........          X   ..........  ..........  Commuter.
 23.1199, 23.1201.                      Fire Extinguisher
                                        Systems, Fire
                                        Extinguishing Agents,
                                        Extinguishing Agent
                                        Containers, Fire
                                        Extinguishing System
                                        Materials.
23.63, 23.67, 23.77..................  Climb: General, Climb--   .........  .........  ..........        10%   ..........          X           X   ..........          X   All.
                                        One Engine, Balked
                                        Landing.
23.703...............................  Take-Off Warning System.      1,000         25  ..........  ..........  ..........          X           X   ..........          X   All.
23.777...............................  Cockpit Controls........        -25  .........  ..........  ..........          X   ..........          X           X   ..........  All.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

    We estimated part 23 airplane manufacturer fixed (added 
certification plus flight test hours) and operator variable (added fuel 
burn plus 10 percent reduction in payload) costs and applied our 
estimated costs to expected fleet delivered in compliance with this 
proposal. The total cost of this rule is the sum of the fixed 
certification cost plus the airplane fuel-burn variable cost multiplied 
by the expected fleet delivered over the analysis period.
    The total fixed certification compliance cost equals the average 
compliance cost multiplied by the expected number of certifications of 
newly delivered part 23 turbojet, turboprop and reciprocating engine 
airplane. In the regulatory evaluation we estimated a base case and 
high case range for the certification costs. This range was based on 
the estimated number of new turbojet certifications. In the base case, 
we estimated five new turbojet certifications in the analysis interval. 
In the high case, we estimated eight new turbojet certifications. We 
will use the high cost case scenario for this analysis.
    We estimated the certification costs for fire extinguishing 
systems, climb, and take-off warning systems. Based on the hours 
provided by the part 23 U.S. airplane manufacturers, ARC members and 
industry association and the Economic Values For FAA Investment and 
Regulatory Decisions, A Guide for the hourly rates.\8\ Table RF4 shows 
the incremental certification costs estimate we calculated.
---------------------------------------------------------------------------

    \8\ http://www.faa.gov/regulations_policies/policy_guidance/benefit_cost/media/050404%20Critical%20Values%20Dec%2031%20Report%2007Jan05.pdf.

                             Table RF4--High Cost Scenario for Part 23 Manufacturers
----------------------------------------------------------------------------------------------------------------
                              Costs                                    Recip        Commuter TP     TJ < 6,000
----------------------------------------------------------------------------------------------------------------
Design..........................................................              $0        $152,020         $94,496
Design..........................................................         (9,501)         (3,801)        (22,803)
Flight Test.....................................................               0         114,400          93,489
Total High Cost.................................................         (9,501)         262,620         165,181
 Certifications........................................               5               4              12
Cost per Cert...................................................         (1,900)          65,655          13,765
----------------------------------------------------------------------------------------------------------------

    We applied the estimated incremental certification costs to the 
each of the small part 23 airplane manufacturing average number of 
historical certifications over a ten-year period. We then divided the 
small part 23 airplane

[[Page 41537]]

manufacturer's annual revenue by the incremental costs. Table RF5 shows 
these results.

                                                                        Table RF5
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                    Annual       Average  certs 10                               Estimated cert
            Company                Employees        revenue                years                Airplane certificated          cost           Percent
--------------------------------------------------------------------------------------------------------------------------------------------------------
Quest.........................              60      $4,600,000  1.00.......................  Turboprop..................         $65,655            1.43
Maule.........................              86       5,700,000  0.20.......................  Recip......................            -380           -0.01
Piper.........................             100       7,600,000  1.00 (Recip) + 33 (TP).....  Recip + Turboprop..........          65,022            0.86
Mooney........................             400      42,083,000  0.17.......................  Recip......................            -317            0.00
Sino Swearingen...............             400      25,300,000  1.00.......................  Turbojet...................          13,765            0.05
Eclipse.......................           1,000       36,700,00  1.00.......................  Turbojet...................          13,765            0.04
--------------------------------------------------------------------------------------------------------------------------------------------------------

    We estimated that the incremental fixed certification cost this 
proposed rule would be less than one percent in five of the six small 
entity part 23 airplane manufacturers, and less than 1.5 percent in the 
remaining one. We do not believe these are significant economic costs. 
Further, we believe that the manufacturers of the part 23 airplanes 
would have additional costs savings associated with the proposal 
standardizes and streamlining the certification process. Additional 
costs savings of the proposed changes to parts 1 and 23 would be to 
eliminate the current workload of exemptions, special conditions, and 
equivalent levels of safety necessary to certificate part 23 turbojets 
and by clarifying frequent non-standardization and misinterpretations 
of current part 23 rules.
    To estimate the incremental variable costs to a part 23 operator, 
we multiplied the annual per-unit fuel burn cost by the expected fleet 
delivered over the analysis interval.
    In the regulatory evaluation, we estimated a minimal base and high 
case cost for the 10 percent loss in capacity occurs the operators may 
incur. The base case was a no cost scenario because the average GA 
airplane has about 3.7 seats and flies about half full.\9\ The cargo 
load factor for all cargo carriers is 60 percent.\10\ Therefore, we 
conclude that the 10 percent reduction in payload caused by the 
proposed sections on climb and balked landings could have a minimum 
cost impact on part 23 airplanes for the base case. For the high case 
we realize that a percentage of the part 23 airplanes, in commuter 
service, could have a load factor over 90 percent on some of their 
flights. Although we believe any capacity affected would be distributed 
over other flights in the operator's network, we estimate the cost of a 
10 percent payload capacity reduction. Table RF6 shows the results of 
our calculations.
---------------------------------------------------------------------------

    \9\ Table 3.15 of the Economic Values For FAA Investment and 
Regulatory Decisions, A Guide
    \10\ Ibid.

                                                    Table RF6
----------------------------------------------------------------------------------------------------------------
                                       Recip         TurboProp      Commuter TP      Total TJ        TJ<6,000
----------------------------------------------------------------------------------------------------------------
Base Case Cost..................              $0              $0          $8,430              $0              $0
High Case Cost..................              $0              $0      $1,413,692              $0      $3,086,919
Number of A/P...................          23,160           1,248           1,066          11,040           1,143
Base Case Cost / A/P............              $0              $0              $8              $0              $0
High Case Cost / A/P............              $0              $0          $1,326              $0          $2,700
A/P Value.......................        $431,681      $3,389,054      $3,389,054      $6,300,000      $6,300,000
% Base of Value.................           0.00%           0.00%           0.00%           0.00%           0.00%
% High of Value.................           0.00%           0.00%           0.04%           0.00%           0.04%
----------------------------------------------------------------------------------------------------------------

    For this proposal, our high case estimate for small business part 
23 operators of turboprop airplanes would pay an additional $1,326 to 
operate a newly certificated airplane. Operators of newly certificated 
and delivered part 23 turbojet airplanes with a maximum take off weight 
less than 6,000 pounds would pay an additional $2,700 to operate a 
newly certificated airplane. Operators would not incur these costs 
unless they purchase a newly certificated part 23 airplane.
    We do not believe that these proposals costs would be a significant 
impact to small entity operators because, even for the high-cost case, 
the compliance costs of this proposal to operators would only be 0.04 
percent for a turboprop and 0.04 percent for a turbojet with a maximum 
take-off weight less than 6,000 pounds, of the price of a newly 
certificated airplane.
    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.

International 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 final rule and has no basis for believing the 
rule will impose substantially different costs on domestic and 
international entities. Thus the FAA believes the rule has a neutral 
trade impact.

Unfunded Mandates Assessment

    Title II of the Unfunded Mandates Reform Act of 1995 (Pub. L. 104-
4) requires each Federal agency to prepare

[[Page 41538]]

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 (in 1995 dollars) 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 $136.1 million in lieu of 
$100 million. This proposed rule does not contain such a mandate; 
therefore, the requirements of Title II of the Act 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.

Regulations Affecting Intrastate Aviation in Alaska

    Section 1205 of the FAA Reauthorization Act of 1996 (110 Stat. 
3213) requires the Administrator, when modifying regulations in Title 
14, Code of Federal Regulations in a manner affecting intrastate 
aviation in Alaska, to consider the extent to which Alaska is not 
served by transportation modes other than aviation and to establish 
appropriate regulatory distinctions. Because this proposed rule would 
apply to the certification of future designs of transport category 
airplanes and their subsequent operation, it could, if adopted, affect 
intrastate aviation in Alaska. The FAA, therefore, specifically 
requests comments on whether there is justification for applying the 
proposed rule differently in intrastate operations in Alaska.

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 312(f) 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 while 
it is a ``significant regulatory action,'' it is not likely to have a 
significant adverse effect on the supply, distribution, or use of 
energy.

Additional 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. To ensure the docket does not contain 
duplicate comments, please send only one copy of written comments, or 
if you are filing comments electronically, please submit your comments 
only one time.
    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. 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 after the comment period has 
closed if it is possible to do so without incurring expense or delay. 
We may change this proposal in light of the comments we receive.
Proprietary or Confidential Business Information
    Do not file in the docket information that you consider to be 
proprietary or confidential business information. Send or deliver this 
information directly to the person identified in the FOR FURTHER 
INFORMATION CONTACT section of this document. You must mark the 
information that you consider proprietary or confidential. If you send 
the information on a disk or CD ROM, mark the outside of the disk or CD 
ROM, and also identify electronically within the disk or CD ROM the 
specific information that is proprietary or confidential.
    Under 14 CFR 11.35(b), when we are aware of proprietary information 
filed with a comment, we do not place it in the docket. We hold it in a 
separate file to which the public does not have access, and we place a 
note in the docket that we have received it. If we receive a request to 
examine or copy this information, we treat it as any other request 
under the Freedom of Information Act (5 U.S.C. 552). We process such a 
request under the DOT procedures found in 49 CFR part 7.
Availability of Rulemaking Documents
    You can get an electronic copy of rulemaking documents using the 
Internet by--
    1. Searching the Federal eRulemaking Portal (http://www.regulations.gov);
    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 or notice number of this rulemaking.
    You may access all documents the FAA considered in developing this 
proposed rule, including economic analyses and technical reports, from 
the Internet through the Federal eRulemaking Portal referenced in 
paragraph (1).

List of Subjects

14 CFR Part 1

    Air transportation.

14 CFR Part 23

    Aviation Safety, Signs, Symbols, Aircraft.

The Proposed Amendments

    In consideration of the foregoing, the Federal Aviation 
Administration proposes to amend Chapter I of Title 14, Code of Federal 
Regulations, 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. Revise the definitions of ``Rated takeoff power'' and ``Rated 
takeoff thrust'' and add the definitions of ``Turbine engine'', 
``Turbojet engine'', and ``Turboprop engine'' in alphabetical order in 
Sec.  1.1 to read as follows:


Sec.  1.1  General definitions.

* * * * *

[[Page 41539]]

    Rated takeoff power, with respect to reciprocating, turbopropeller, 
and turboshaft engine type certification, means the approved brake 
horsepower that is developed statically under standard sea level 
conditions, within the engine operating limitations established under 
part 33 of this chapter, and limited in use--
    (1) To periods of not more than 5 minutes for takeoff operations 
with reciprocating, turbopropeller, and turboshaft engines; and
    (2) When specifically requested by the engine manufacturer, to 
periods of not more than 10 minutes for one-engine-inoperative takeoff 
operations with turbopropeller engines.
    Rated takeoff thrust, with respect to turbojet engine type 
certification, means the approved turbojet thrust that is developed 
statically under standard sea level conditions, without fluid injection 
and without the burning of fuel in a separate combustion chamber, 
within the engine operating limitations established under part 33 of 
this chapter, and limited in use--
    (1) To periods of not more than 5 minutes for takeoff operations; 
and
    (2) When specifically requested by the engine manufacturer, to 
periods of not more than 10 minutes for one-engine-inoperative takeoff 
operations.
* * * * *
    Turbine engine, with respect to part 23 airplane type 
certification, consists of an air compressor, a combustion section, and 
a turbine. Thrust is produced by increasing the velocity of the air 
flowing through the engine.
    Turbojet engine, with respect to part 23 airplane type 
certification, is a turbine engine which produces its thrust entirely 
by accelerating the air through the engine.
    Turboprop engine, with respect to part 23 airplane type 
certification, is a turbine engine which drives a propeller through a 
reduction gearing arrangement. Most of the energy in the exhaust gases 
is converted into torque, rather than using its acceleration to drive 
the airplane.
* * * * *

PART 23--AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND 
COMMUTER CATEGORY AIRPLANES

    3. The authority citation for part 23 continues to read as follows:

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

    4. Amend Sec.  23.3 by revising the first sentence in paragraph (d) 
to read as follows:


Sec.  23.3  Airplane categories.

* * * * *
    (d) The commuter category is limited to multiengine airplanes that 
have a seating configuration, excluding pilot seats, of 19 or less, and 
a maximum certificated takeoff weight of 19,000 pounds or less. * * *
* * * * *
    5. Amend Sec.  23.45 by revising the introductory text of paragraph 
(h) to read as follows:


Sec.  23.45  General.

* * * * *
    (h) For multiengine turbojet powered airplanes over 6,000 pounds in 
the normal, utility, and acrobatic category and commuter category 
airplanes the following also apply:
* * * * *
    6. Amend Sec.  23.49 by revising the section heading and the 
introductory text of paragraphs (a) and (c) to read as follows:


Sec.  23.49  Stalling speed.

    (a) VSO (maximum landing flap configuration) and 
VS1 are the stalling speeds or the minimum steady flight 
speeds, in knots (CAS), at which the airplane is controllable with--
     * * *
    (c) Except as provided in paragraph (d) of this section, 
VSO at maximum weight may not exceed 61 knots for--
* * * * *
    7. Amend Sec.  23.51 by revising paragraph (b)(1) introductory text 
and paragraph (c) introductory text to read as follows:


Sec.  23.51  Takeoff speeds.

* * * * *
    (b) * * *
    (1) For multiengine airplanes, the highest of--
     * * *
    (c) For normal, utility, and acrobatic category multiengine 
turbojet airplanes of more than 6,000 pounds maximum weight and 
commuter category airplanes, the following apply:
* * * * *
    8. Amend Sec.  23.53 by revising paragraph (c) to read as follows:


Sec.  23.53  Takeoff performance.

* * * * *
    (c) For normal, utility, and acrobatic category multiengine 
turbojet airplanes of more than 6,000 pounds maximum weight and 
commuter category airplanes, takeoff performance, as required by 
Sec. Sec.  23.55 through 23.59, must be determined with the operating 
engine(s) within approved operating limitations.
    9. Amend Sec.  23.55 by revising the introductory text to read as 
follows:


Sec.  23.55  Accelerate-stop distance.

    For normal, utility, and acrobatic category multiengine turbojet 
airplanes of more than 6,000 pounds maximum weight and commuter 
category airplanes, the accelerate-stop distance must be determined as 
follows:
* * * * *
    10. Amend Sec.  23.57 by revising the introductory text to read as 
follows:


Sec.  23.57  Takeoff path.

    For normal, utility, and acrobatic category multiengine turbojet 
airplanes of more than 6,000 pounds maximum weight and commuter 
category airplanes, the takeoff path is as follows:
* * * * *
    11. Amend Sec.  23.59 by revising the introductory text to read as 
follows:


Sec.  23.59  Takeoff distance and takeoff run.

    For normal, utility, and acrobatic category multiengine turbojet 
airplanes of more than 6,000 pounds maximum weight and commuter 
category airplanes, the takeoff distance and, at the option of the 
applicant, the takeoff run, must be determined.
* * * * *
    12. Amend Sec.  23.61 by revising the introductory text to read as 
follows:


Sec.  23.61  Takeoff flight path.

    For normal, utility, and acrobatic category multiengine turbojet 
airplanes of more than 6,000 pounds maximum weight and commuter 
category airplanes, the takeoff flight path must be determined as 
follows:
* * * * *
    13. Amend Sec.  23.63 by revising the introductory text of 
paragraphs (c) and (d) to read as follows:


Sec.  23.63  Climb: General.

* * * * *
    (c) For reciprocating engine-powered airplanes of more than 6,000 
pounds maximum weight, single-engine turbines, and multiengine turbine 
airplanes of 6,000 pounds or less maximum weight in the normal, 
utility, and acrobatic category, compliance must be shown at weights as 
a function of airport altitude and ambient temperature, within the 
operational limits established for takeoff and landing, respectively, 
with--
* * * * *
    (d) For multiengine turbine airplanes over 6,000 pounds maximum 
weight in the normal, utility, and acrobatic category and commuter 
category airplanes, compliance must be shown at weights as a function 
of airport altitude

[[Page 41540]]

and ambient temperature within the operational limits established for 
takeoff and landing, respectively, with--
* * * * *
    14. Amend Sec.  23.67 by:
    a. Revising paragraph (b) introductory text and (b)(1) introductory 
text;
    b. Redesignating paragraph (c) as paragraph (d)
    c. Revising newly redesignated paragraph (d) introductory text, 
paragraph (d)(2) introductory text, paragraph (d)(3) introductory text, 
and paragraph (d)(4) introductory text; and
    d. Adding new paragraph (c).
    The revisions and addition read as follows:


Sec.  23.67  Climb: One-engine inoperative.

* * * * *
    (b) For normal, utility, and acrobatic category reciprocating 
engine-powered airplanes of more than 6,000 pounds maximum weight, and 
turbopropeller-powered airplanes in the normal, utility, and acrobatic 
category--
    (1) The steady gradient of climb at an altitude of 400 feet above 
the takeoff may be no less than 1 percent with the--
* * * * *
    (c) For normal, utility, and acrobatic category turbojet engine-
powered airplanes of 6,000 pounds or less maximum weight--
    (1) The steady gradient of climb at an altitude of 400 feet above 
the takeoff may be no less than 1.2 percent with the--
    (i) Critical engine inoperative;
    (ii) Remaining engine(s) at takeoff power;
    (iii) Landing gear retracted;
    (iv) Wing flaps in the takeoff position(s); and
    (v) Climb speed equal to that achieved at 50 feet in the 
demonstration of Sec.  23.53.
    (2) The steady gradient of climb may not be less than 0.75 percent 
at an altitude of 1,500 feet above the takeoff surface, or landing 
surface, as appropriate, with the--
    (i) Critical engine inoperative:
    (ii) Remaining engine(s) at not more than maximum continuous power;
    (iii) Landing gear retracted;
    (iv) Wing flaps retracted; and
    (v) Climb speed not less than 1.2 VS1.
    (d) For turbojet powered airplanes over 6,000 pounds maximum weight 
in the normal, utility and acrobatic category and commuter category 
airplanes, the following apply:
* * * * *
    (2) Takeoff; landing gear retracted. The steady gradient of climb 
at an altitude of 400 feet above the takeoff surface must be at least 
2.0 percent of two-engine airplanes, 2.3 percent for three-engine 
airplanes, and 2.6 percent for four-engine airplanes with--
* * * * *
    (3) Enroute. The steady gradient of climb at an altitude of 1,500 
feet above the takeoff or landing surface, as appropriate, must be at 
least 1.2 percent for two-engine airplanes, 1.5 percent for three-
engine airplanes, and 1.7 percent for four-engine airplanes with--
* * * * *
    (4) Discontinued approach. The steady gradient of climb at an 
altitude of 400 feet above the landing surface must be at least 2.1 
percent for two-engine airplanes, 2.4 percent for three-engine 
airplanes, and 2.7 percent for four-engine airplanes, with--
* * * * *
    15. Revise Sec.  23.73 to read as follows:


Sec.  23.73  Reference landing approach speed.

    (a) For normal, utility, and acrobatic category reciprocating 
engine-powered airplanes of 6,000 pounds or less maximum weight, the 
reference landing approach speed, VREF, may not be less than 
the greater of VMC, determined in Sec.  23.149(b) with the 
wing flaps in the most extended takeoff position, and 1.3 
VS1.
    (b) For normal, utility, and acrobatic category turbine powered 
airplanes of 6,000 pounds or less maximum weight, turboprops of more 
than 6,000 pounds maximum weight, and reciprocating engine-powered 
airplanes of more than 6,000 pounds maximum weight, the reference 
landing approach speed, VREF, may not be less than the 
greater of VMC, determined in Sec.  23.149(c), and 1.3 
VS1.
    (c) For normal, utility, and acrobatic category turbojet engine-
powered airplanes of more than 6,000 pounds maximum weight and commuter 
category airplanes, the reference landing approach speed, 
VREF, may not be less than the greater of 1.05 
VMC, determined in Sec.  23.149(c), and 1.3 VS1.
    16. Amend Sec.  23.77 by revising the introductory text of 
paragraphs (b) and (c) to read as follows:


Sec.  23.77  Balked landing.

* * * * *
    (b) Each normal, utility, and acrobatic category reciprocating 
engine-powered and single engine turbine powered airplane of more than 
6,000 pounds maximum weight, and multiengine turbine engine-powered 
airplane of 6,000 pounds or less maximum weight in the normal, utility, 
and acrobatic category must be able to maintain a steady gradient of 
climb of at least 2.5 percent with--
* * * * *
    (c) Each normal, utility, and acrobatic multiengine turbine powered 
airplane over 6,000 pounds maximum weight and each commuter category 
airplane must be able to maintain a steady gradient of climb of at 
least 3.2 percent with--
* * * * *
    17. Amend Sec.  23.175 by adding a new paragraph (b)(3) to read as 
follows:


Sec.  23.175  Demonstration of static longitudinal stability.

* * * * *
    (b) * * *
    (3) Maximum speed for stability characteristics, VFC/MFC. 
VFC/MFC may not be less than a speed midway 
between VMO/MMO and VDF/MDF 
except that, for altitudes where Mach number is the limiting factor, 
MFC need not exceed the Mach number at which effective speed 
warning occurs.
* * * * *
    18. Amend Sec.  23.177 by revising paragraphs (a), (b), and (d) to 
read as follows:


Sec.  23.177  Static directional and lateral stability.

    (a)(1) The static directional stability, as shown by the tendency 
to recover from a wings level sideslip with the rudder free, must be 
positive for any landing gear and flap position appropriate to the 
takeoff, climb, cruise, approach, and landing configurations. This must 
be shown with symmetrical power up to maximum continuous power, and at 
speeds from 1.2 VS1 up to the landing gear or wing flap 
operating limit speeds, or VNO or VFC/
MFC, whichever is appropriate.
    (2) The angle of sideslip for these tests must be appropriate to 
the type of airplane. The rudder pedal force may not reverse at larger 
angles of sideslip, up to that at which full rudder is used or a 
control force limit in Sec.  23.143 is reached, whichever occurs first, 
and at speeds from 1.2 VS1 to VO.
    (b)(1) The static lateral stability, as shown by the tendency to 
raise the low wing in a sideslip with the aileron controls free, may 
not be negative for any landing gear and flap position appropriate to 
the takeoff, climb, cruise, approach, and landing configurations. This 
must be shown with symmetrical power from idle up to 75 percent of 
maximum continuous power at speeds from 1.2 VS1 in the 
takeoff configuration(s) and at speeds from 1.3 VS1 in other 
configurations, up to the maximum allowable airspeed for the 
configuration being investigated, (VFE,

[[Page 41541]]

VLE, VNO, VFC/MFC, 
whichever is appropriate) in the takeoff, climb, cruise, descent, and 
approach configurations. For the landing configuration, the power must 
be that necessary to maintain a 3-degree angle of descent in 
coordinated flight.
    (2) The static lateral stability may not be negative at 1.2 
VS1 in the takeoff configuration, or at 1.3 VS1 
in other configurations.
    (3) The angle of sideslip for these tests must be appropriate to 
the type of airplane, but in no case may the constant heading sideslip 
angle be less than that obtainable with a 10 degree bank or, if less, 
the maximum bank angle obtainable with full rudder deflection or 150 
pound rudder force.
* * * * *
    (d)(1) In straight, steady slips at 1.2 VS1 for any 
landing gear and flap position appropriate to the takeoff, climb, 
cruise, approach, and landing configurations, and for any symmetrical 
power conditions up to 50 percent of maximum continuous power, the 
aileron and rudder control movements and forces must increase steadily, 
but not necessarily in constant proportion, as the angle of sideslip is 
increased up to the maximum appropriate to the type of airplane.
    (2) At larger slip angles, up to the angle at which the full rudder 
or aileron control is used or a control force limit contained in Sec.  
23.143 is reached, the aileron and rudder control movements and forces 
may not reverse as the angle of sideslip is increased.
    (3) Rapid entry into, and recovery from, a maximum sideslip 
considered appropriate for the airplane may not result in 
uncontrollable flight characteristics.
    19. Amend Sec.  23.181 by revising paragraph (b) to read as 
follows:


Sec.  23.181  Dynamic stability.

* * * * *
    (b) Any combined lateral-directional oscillations (``Dutch roll'') 
occurring between the stalling speed and the maximum allowable speed 
appropriate to the configuration of the airplane with the primary 
controls in both free and fixed position, must be damped to 1/10 
amplitude in:
    (1) Seven (7) cycles below 18,000 feet, and
    (2) Thirteen (13) cycles from 18,000 feet to the certified maximum 
altitude.
* * * * *
    20. Amend Sec.  23.201 by revising paragraphs (d) and (e) and by 
adding a new paragraph (f) to read as follows:


Sec.  23.201  Wings level stall.

* * * * *
    (d) During the entry into and the recovery from the maneuver, it 
must be possible to prevent more than 15 degrees of roll or yaw by the 
normal use of controls except as provided for in paragraph (e) of this 
section.
    (e) For airplanes approved with a maximum operating altitude above 
25,000 feet, during the entry into and the recovery from stalls 
performed above 25,000 feet, it must be possible to prevent more than 
25 degrees of roll or yaw by the normal use of controls.
    (f) Compliance with the requirements of this section must be shown 
under the following conditions:
    (1) Wing flaps: Retracted, fully extended, and each intermediate 
normal operating position, as appropriate for the phase of flight.
    (2) Landing gear: Retracted and extended as appropriate for the 
altitude.
    (3) Cowl flaps: Appropriate to configuration.
    (4) Spoilers/speedbrakes: Retracted and extended unless they have 
little to no effect at low speeds.
    (5) Power:
    (i) Power/Thrust off; and
    (ii) For reciprocating engine powered airplanes: 75 percent maximum 
continuous power. However, if the power-to-weight ratio at 75 percent 
of maximum continuous power results in nose-high attitudes exceeding 30 
degrees, the test must be carried out with the power required for level 
flight in the landing configuration at maximum landing weight and a 
speed of 1.4 VSO, except that the power may not be less than 
50 percent of maximum continuous power; or
    (iii) For turbine engine powered airplanes: The maximum engine 
thrust, except that it need not exceed the thrust necessary to maintain 
level flight at 1.6 VS1 (where VS1 corresponds to 
the stalling speed with flaps in the approach position, the landing 
gear retracted, and maximum landing weight).
    (6) Trim at 1.5 VS1 or the minimum trim speed, whichever 
is higher.
    (7) Propeller: Full increase r.p.m. position for the power off 
condition.
    21. Amend Sec.  23.203 by revising paragraph (c) to read as 
follows:


Sec.  23.203  Turning flight and accelerated turning stalls.

* * * * *
    (c) Compliance with the requirements of this section must be shown 
under the following conditions:
    (1) Wings flaps: Retracted, fully extended, and each intermediate 
normal operating position as appropriate for the phase of flight.
    (2) Landing gear: Retracted and extended as appropriate for the 
altitude.
    (3) Cowl flaps: Appropriate to configuration.
    (4) Spoilers/speedbrakes: Retracted and extended unless they have 
little to no effect at low speeds.
    (5) Power:
    (i) Power/Thrust off; and
    (ii) For reciprocating engine powered airplanes: 75 percent maximum 
continuous power. However, if the power-to-weight ratio at 75 percent 
of maximum continuous power results in nose-high attitudes exceeding 30 
degrees, the test may be carried out with the power required for level 
flight in the landing configuration at maximum landing weight and a 
speed of 1.4 VSO, except that the power may not be less than 
50 percent of maximum continuous power; or
    (iii) For turbine engine powered airplanes: The maximum engine 
thrust, except that it need not exceed the thrust necessary to maintain 
level flight at 1.6 VS1 (where VS1 corresponds to 
the stalling speed with flaps in the approach position, the landing 
gear retracted, and maximum landing weight).
    (6) Trim: The airplane trimmed at 1.5 VS1.
    (7) Propeller: Full increase rpm position for the power off 
condition.
    22. Revise Sec.  23.251 to read as follows:


Sec.  23.251  Vibration and buffeting.

    (a) There may be no vibration or buffeting severe enough to result 
in structural damage, and each part of the airplane must be free from 
excessive vibration, under any appropriate speed and power conditions 
up to VD/MD, or VDF/MDF for 
turbojets. In addition, there may be no buffeting in any normal flight 
condition, including configuration changes during cruise, severe enough 
to interfere with the satisfactory control of the airplane or cause 
excessive fatigue to the flight crew. Stall warning buffeting within 
these limits is allowable.
    (b) There may be no perceptible buffeting condition in the cruise 
configuration in straight flight at any speed up to VMO/
MMO, except stall buffeting, which is allowable.
    (c) For airplanes with MD greater than M 0.6 and a 
maximum operating altitude greater than 25,000 feet, the positive 
maneuvering load factors at which the onset of perceptible buffeting 
occurs must be determined with the airplane in the cruise configuration 
for the ranges of airspeed or Mach number, weight, and altitude for 
which the airplane is to be certificated. The envelopes of load factor, 
speed, altitude, and weight must provide a sufficient range of speeds 
and load factors for

[[Page 41542]]

normal operations. Probable inadvertent excursions beyond the 
boundaries of the buffet onset envelopes may not result in unsafe 
conditions.
    23. Amend Sec.  23.253 by revising paragraphs (b)(1) and (b)(2), 
and by adding a new paragraph (b)(3) to read as follows:


Sec.  23.253  High speed characteristics.

* * * * *
    (b) * * *
    (1) Exceptional piloting strength or skill;
    (2) Exceeding VD/MD, or VDF/
MDF for turbojet, the maximum speed shown under Sec.  
23.251, or the structural limitations; and
    (3) Buffeting that would impair the pilot's ability to read the 
instruments or to control the airplane for recovery.
* * * * *
    24. Section 23.255 is added to subpart B to read as follows:


Sec.  23.255  Out of trim characteristics.

    For airplanes with an MD greater than M 0.6 and that 
incorporate a trimmable horizontal stabilizer, the following 
requirements for out-of-trim characteristics apply:
    (a) From an initial condition with the airplane trimmed at cruise 
speeds up to VMO/MMO, the airplane must have 
satisfactory maneuvering stability and controllability with the degree 
of out-of-trim in both the airplane nose-up and nose-down directions, 
which results from the greater of the following:
    (1) A three-second movement of the longitudinal trim system at its 
normal rate for the particular flight condition with no aerodynamic 
load (or an equivalent degree of trim for airplanes that do not have a 
power-operated trim system), except as limited by stops in the trim 
system, including those required by Sec.  23.655(b) for adjustable 
stabilizers; or
    (2) The maximum mis-trim that can be sustained by the autopilot 
while maintaining level flight in the high speed cruising condition.
    (b) In the out-of-trim condition specified in paragraph (a) of this 
section, when the normal acceleration is varied from +l g to the 
positive and negative values specified in paragraph (c) of this 
section, the following apply:
    (1) The stick force versus g curve must have a positive slope at 
any speed up to and including VFC/MFC; and
    (2) At speeds between VFC/MFC and 
VDF/MDF, the direction of the primary 
longitudinal control force may not reverse.
    (c) Except as provided in paragraphs (d) and (e) of this section, 
compliance with the provisions of paragraph (a) of this section must be 
demonstrated in flight over the acceleration range as follows:
    (1) -1 g to +2.5g; or
    (2) 0 g to 2.0g, and extrapolating by an acceptable method to -1g 
and +2.5g.
    (d) If the procedure set forth in paragraph (c)(2) of this section 
is used to demonstrate compliance and marginal conditions exist during 
flight test with regard to reversal of primary longitudinal control 
force, flight tests must be accomplished from the normal acceleration 
at which a marginal condition is found to exist to the applicable limit 
specified in paragraph (b)(1) of this section.
    (e) During flight tests required by paragraph (a) of this section, 
the limit maneuvering load factors, prescribed in Sec. Sec.  23.333(b) 
and 23.337, need not be exceeded. In addition, the entry speeds for 
flight test demonstrations at normal acceleration values less than 1g 
must be limited to the extent necessary to accomplish a recovery 
without exceeding VDF/MDF.
    (f) In the out-of-trim condition specified in paragraph (a) of this 
section, it must be possible from an overspeed condition at 
VDF/MDF to produce at least 1.5g for recovery by 
applying not more than 125 pounds of longitudinal control force using 
either the primary longitudinal control alone or the primary 
longitudinal control and the longitudinal trim system. If the 
longitudinal trim is used to assist in producing the required load 
factor, it must be shown at VDF/MDF that the 
longitudinal trim can be actuated in the airplane nose-up direction 
with the primary surface loaded to correspond to the least of the 
following airplane nose-up control forces:
    (1) The maximum control forces expected in service, as specified in 
Sec. Sec.  23.301 and 23.397.
    (2) The control force required to produce 1.5g.
    (3) The control force corresponding to buffeting or other phenomena 
of such intensity that it is a strong deterrent to further application 
of primary longitudinal control force.
    25. Amend Sec.  23.561 by adding new paragraphs (e)(1) and (e)(2) 
to read as follows:


Sec.  23.561  General.

* * * * *
    (e) * * *
    (1) For turbojet engines mounted inside the fuselage, aft of the 
cabin, it must be shown by test or analysis that the engine and 
attached accessories, and the engine mounting structure--
    (i) Can withstand a forward acting static ultimate inertia load 
factor of 18.0g plus the maximum takeoff engine thrust; or
    (ii) The airplane structure is designed to deflect the engine and 
its attached accessories away from the cabin should the engine mounts 
fail.
    (2) [Reserved]
    26. Amend Sec.  23.562 by revising paragraphs (a) introductory 
text, (b) introductory text, and (c)(5)(ii) to read as follows:


Sec.  23.562  Emergency landing dynamic conditions.

    (a) Each seat/restraint system for use in a normal, utility, or 
acrobatic category airplane, or in a commuter category turbojet powered 
airplane, must be designed to protect each occupant during an emergency 
landing when--
* * * * *
    (b) Except for those seat/restraint systems that are required to 
meet paragraph (d) of this section, each seat/restraint system for crew 
or passenger occupancy in a normal, utility, or acrobatic category 
airplane, or in a commuter category turbojet powered airplane, must 
successfully complete dynamic tests or be demonstrated by rational 
analysis supported by dynamic tests, in accordance with each of the 
following conditions. These tests must be conducted with an occupant 
simulated by an anthropomorphic test dummy (ATD) defined by 49 CFR part 
572, subpart B, or an FAA-approved equivalent, with a nominal weight of 
170 pounds and seated in the normal upright position.
* * * * *
    (c) * * *
    (5) * * *
    (ii) The value of HIC is defined as--
    [GRAPHIC] [TIFF OMITTED] TP17AU09.000
    

[[Page 41543]]


Where:

t1 is the initial integration time, expressed in seconds, 
t2 is the final integration time, expressed in seconds, 
and a(t) is the total acceleration vs. time curve for the head 
expressed as a multiple of g (units of gravity).
* * * * *
    27. Amend Sec.  23.571 by adding a new paragraph (d) to read as 
follows:


Sec.  23.571  Metallic pressurized cabin structures.

* * * * *
    (d) If certification for operation above 41,000 feet is requested, 
a damage tolerance evaluation of the fuselage pressure boundary per 
Sec.  23.573(b) must be conducted and the evaluation must factor in the 
environmental requirements of Sec.  23.841.
    28. Amend Sec.  23.573 by adding a new paragraph (c) to read as 
follows:


Sec.  23.573  Damage tolerance and fatigue evaluation of structure.

* * * * *
    (c) If certification for operation above 41,000 feet is requested, 
the damage tolerance evaluation of this paragraph for the fuselage 
pressure boundary must factor in the requirements of Sec.  23.841.
    29. Amend Sec.  23.574 by adding a new paragraph (c) to read as 
follows:


Sec.  23.574  Metallic damage tolerance and fatigue evaluation of 
commuter category airplanes.

* * * * *
    (c) If certification for operation above 41,000 feet is requested, 
the damage tolerance evaluation of this paragraph for the fuselage 
pressure boundary must factor in the requirements of Sec.  23.841.
    30. Amend Sec.  23.629 by revising paragraphs (b)(1), (b)(3), 
(b)(4), and (c) to read as follows:


Sec.  23.629  Flutter.

* * * * *
    (b) * * *
    (1) Proper and adequate attempts to induce flutter have been made 
within the speed range up to VD/MD;
* * * * *
    (3) A proper margin of damping exists at VD/
MD, or VDF/MDF for turbojet airplanes; 
and
    (4) As VD/MD (or VDF/
MDF for turbojet airplanes) is approached, there may not be 
a large or rapid reduction in damping.
    (c) Any rational analysis used to predict freedom from flutter, 
control reversal and divergence must cover all speeds up to 1.2 
VD/MD, or 1.2 VDF/MDF for 
turbojet airplanes.
* * * * *
    31. Amend Sec.  23.703 by revising the introductory text and 
paragraph (b) to read as follows:


Sec.  23.703  Takeoff warning system.

    For all airplanes with a maximum weight more than 6,000 pounds and 
all turbojet airplanes, unless it can be shown that a lift or 
longitudinal trim device that affects the takeoff performance of the 
airplane would not give an unsafe takeoff configuration when selected 
out of an approved takeoff position, a takeoff warning system must be 
installed and meet the following requirements:
* * * * *
    (b) For the purpose of this section, an unsafe takeoff 
configuration is the inability to rotate or the inability to prevent an 
immediate stall after rotation.
    32. Amend Sec.  23.735 by revising paragraph (e) to read as 
follows:


Sec.  23.735  Brakes.

* * * * *
    (e) For airplanes required to meet Sec.  23.55, the rejected 
takeoff brake kinetic energy capacity rating of each main wheel brake 
assembly may not be less than the kinetic energy absorption 
requirements determined under either of the following methods--
    (1) The brake kinetic energy absorption requirements must be based 
on a conservative rational analysis of the sequence of events expected 
during a rejected takeoff at the design takeoff weight.
    (2) Instead of a rational analysis, the kinetic energy absorption 
requirements for each main wheel brake assembly may be derived from the 
following formula--

KE = 0.0443 WV\2\/N

Where:

KE = Kinetic energy per wheel (ft.-lbs.);
W = Design takeoff weight (lbs.);
V = Ground speed, in knots, associated with the maximum value of 
V1 selected in accordance with Sec.  23.51(c)(1);
N = Number of main wheels with brakes.

    33. Amend Sec.  23.777 by revising paragraph (d) to read as 
follows:


Sec.  23.777  Cockpit controls.

* * * * *
    (d) When separate and distinct control levers are co-located (such 
as located together on the pedestal), the control location order from 
left to right must be power (thrust) lever, propeller (rpm control), 
and mixture control (condition lever and fuel cut-off for turbine-
powered airplanes). Power (thrust) levers must be at least one inch 
higher or longer than propeller (rpm control) or mixture controls to 
make them more prominent. Carburetor heat or alternate air control must 
be to the left of the throttle or at least eight inches from the 
mixture control when located other than on a pedestal. Carburetor heat 
or alternate air control, when located on a pedestal, must be aft or 
below the power (thrust) lever. Supercharger controls must be located 
below or aft of the propeller controls. Airplanes with tandem seating 
or single-place airplanes may utilize control locations on the left 
side of the cabin compartment; however, location order from left to 
right must be power (thrust) lever, propeller (rpm control), and 
mixture control.
* * * * *
    34. Amend Sec.  23.807 by adding a new paragraph (e)(3) to read as 
follows:


Sec.  23.807  Emergency exits.

* * * * *
    (e) * * *
    (3) In lieu of paragraph (e)(2) of this section, if any side exit 
or exits cannot be above the waterline, a device may be placed at each 
of such exit(s) prior to ditching. This device must slow the inflow of 
water when such exit(s) is opened with the airplane in a ditching 
emergency. For commuter category airplanes, the clear opening of such 
exit or exits must meet the requirements defined in paragraph (d) of 
this section.
    35. Amend Sec.  23.831 by adding paragraphs (c) and (d) to read as 
follows:


Sec.  23.831  Ventilation.

* * * * *
    (c) For turbojet powered pressurized airplanes, under normal 
operating conditions and in the event of any probable failure 
conditions of any system which would adversely affect the ventilating 
air, the ventilation system must provide reasonable passenger comfort. 
The ventilation system must also provide a sufficient amount of 
uncontaminated air to enable the crew members to perform their duties 
without undue discomfort or fatigue and to provide reasonable passenger 
comfort. For normal operating conditions, the ventilation system must 
be designed to provide each occupant with at least 0.55 pounds of fresh 
air per minute. In the event of the loss of one source of fresh air, 
the supply of fresh airflow must not be less than 0.4 pounds per minute 
for any period exceeding five minutes.
    (d) Other probable and improbable Environmental Control System 
failure conditions that adversely affect the passenger and crew 
compartment environmental conditions may not affect crew performance so 
as to result in a hazardous condition, and no occupant shall sustain 
permanent physiological harm.

[[Page 41544]]

    36. Amend Sec.  23.841 by revising paragraphs (a) and (b)(6), and 
by adding paragraphs (c), (d), and (e) to read as follows:


Sec.  23.841  Pressurized cabins.

    (a) If certification for operation above 25,000 feet is requested, 
the airplane must be able to maintain a cabin pressure altitude of not 
more than 15,000 feet, in the event of any probable failure condition 
in the pressurization system. During the decompression, the cabin 
altitude shall not exceed 15,000 feet for more than 10 seconds and 
25,000 feet for any duration.
    (b) * * *
    (6) Warning indication at the pilot station to indicate when the 
safe or preset pressure differential is exceeded and when a cabin 
pressure altitude of 10,000 feet is exceeded. The 10,000 foot cabin 
altitude warning may be increased up to 15,000 feet for operations from 
high altitude airfields (10,000 to 15,000 feet) provided:
    (i) The landing or the take off modes (normal or high altitude) are 
clearly indicated to the flight crew.
    (ii) Selection of normal or high altitude airfield mode requires no 
crew action beyond normal pressurization system operation.
    (iii) The pressurization system is designed to ensure cabin 
altitude does not exceed 10,000 feet when in flight above flight level 
(FL) 250.
    (iv) The pressurization system and cabin altitude warning system is 
designed to ensure cabin altitude warning at 10,000 feet when in flight 
above FL250.
* * * * *
    (c) If certification for operation above 41,000 feet and not more 
than 45,000 feet is requested,
    (1) The airplane must prevent cabin pressure altitude from 
exceeding the following after decompression from any probable 
pressurization system failure in conjunction with any undetected, 
latent pressurization system failure condition:
    (i) If depressurization analysis shows that the cabin altitude does 
not exceed 25,000 feet, the pressurization system must prevent the 
cabin altitude from exceeding the cabin altitude-time history shown in 
Figure 1 of this section.
    (ii) Maximum cabin altitude is limited to 30,000 feet. If cabin 
altitude exceeds 25,000 feet, the maximum time the cabin altitude may 
exceed 25,000 feet is 2 minutes; time starting when the cabin altitude 
exceeds 25,000 feet and ending when it returns to 25,000 feet.
    (2) The airplane must prevent cabin pressure altitude from 
exceeding the following after decompression from any single 
pressurization system failure in conjunction with any probable fuselage 
damage:
    (i) If depressurization analysis shows that the cabin altitude does 
not exceed 37,000 feet, the pressurization system must prevent the 
cabin altitude from exceeding the cabin altitude-time history shown in 
Figure 2 of this section.
    (ii) Maximum cabin altitude is limited to 40,000 feet. If cabin 
altitude exceeds 37,000 feet, the maximum time the cabin altitude may 
exceed 25,000 feet is 2 minutes; time starting when the cabin altitude 
exceeds 25,000 feet and ending when it returns to 25,000 feet.
    (3) In showing compliance with paragraphs (c)(1) and (c)(2) of this 
section, it may be assumed that an emergency descent is made by an 
approved emergency procedure. A 17-second crew recognition and reaction 
time must be applied between cabin altitude warning and the initiation 
of an emergency descent. Fuselage structure, engine and system failures 
are to be considered in evaluating the cabin decompression.
[GRAPHIC] [TIFF OMITTED] TP17AU09.001


    Note: For Figure 1, time starts at the moment cabin altitude 
exceeds 10,000 feet during decompression.


[[Page 41545]]


[GRAPHIC] [TIFF OMITTED] TP17AU09.002


    Note: For Figure 2, time starts at the moment cabin altitude 
exceeds 10,000 feet during decompression.

    (d) If certification for operation above 45,000 feet and not more 
than 51,000 feet is requested--
    (1) Pressurized cabins must be equipped to provide a cabin pressure 
altitude of not more than 8,000 feet at the maximum operating altitude 
of the airplane under normal operating conditions.
    (2) The airplane must prevent cabin pressure altitude from 
exceeding the following after decompression from any failure condition 
not shown to be extremely improbable:
    (i) Twenty-five thousand (25,000) feet for more than 2 minutes, or
    (ii) Forty thousand (40,000) feet for any duration.
    (3) Fuselage structure, engine and system failures are to be 
considered in evaluating the cabin decompression.
    (4) In addition to the cabin altitude indicating means in (b)(6) of 
this section, an aural or visual signal must be provided to warn the 
flight crew when the cabin pressure altitude exceeds 10,000 feet.
    (5) The sensing system and pressure sensors necessary to meet the 
requirements of (b)(5), (b)(6), and (d)(4) of this section and Sec.  
23.1447(e), must, in the event of low cabin pressure, actuate the 
required warning and automatic presentation devices without any delay 
that would significantly increase the hazards resulting from 
decompression.
    (e) If certification for operation above 41,000 feet is requested, 
additional damage-tolerance requirements are necessary to prevent 
fatigue damage that could result in a loss of pressure that exceeds the 
requirements of paragraphs (c) and (d) of this section. Sufficient full 
scale fatigue test evidence must be provided to demonstrate that this 
type of pressure loss due to fatigue cracking will not occur within the 
Limit of Validity of the Maintenance program for the airplane. In 
addition, a damage tolerance evaluation of the fuselage pressure 
boundary must be performed assuming visually detectable cracks and the 
maximum damage size for which the requirements of paragraphs (c) and 
(d) of this section can be met. Based on this evaluation, inspections 
or other procedures must be established and included in the Limitations 
Section of the Instructions for Continued Airworthiness required by 
Sec.  23.1529.
    37. Amend Sec.  23.853 by revising paragraph (d)(2) to read as 
follows:


Sec.  23.853  Passenger and crew compartment interiors.

* * * * *
    (d) * * *
    (2) Lavatories must have ``No Smoking'' or ``No Smoking in 
Lavatory'' placards located conspicuously on each side of the entry 
door.
* * * * *
    38. Add a new Sec.  23.856 to read as follows:


Sec.  23.856  Thermal/Acoustic insulation materials.

    Thermal/acoustic insulation material installed in the fuselage must 
meet the flame propagation test requirements of part II of Appendix F 
to this part, or other approved equivalent test requirements. This 
requirement does not apply to ``small parts,'' as defined in part I of 
Appendix F of this part.
    39. Amend Sec.  23.903 by revising paragraph (b)(2) to read as 
follows:


Sec.  23.903  Engines.

* * * * *
    (b) * * *
    (2) For engines embedded in the fuselage behind the cabin, the 
effects of a fan exiting forward of the inlet case (fan disconnect) 
must be addressed, the passengers must be protected, and the airplane 
must have the ability to maintain controlled flight and landing.
* * * * *
    40. Amend Sec.  23.1141 by adding a new paragraph (h) to read as 
follows:


Sec.  23.1141  Powerplant controls: General.

* * * * *
    (h) Electronic engine control system installations must meet the 
requirements of Sec.  23.1309.
    41. Amend Sec.  23.1165 by revising paragraph (f) to read as 
follows:


Sec.  23.1165  Engine ignition systems.

* * * * *
    (f) In addition, for commuter category airplanes, each turbine 
engine ignition system must be an essential electrical load.
    42. Amend Sec.  23.1193 by revising paragraph (g) to read as 
follows:


Sec.  23.1193  Cowling and nacelle.

* * * * *
    (g) In addition, for all turbojet airplanes and commuter category 
airplanes, the airplane must be designed so that no fire originating in 
any engine compartment can enter, either through openings or by burn 
through, any other region where it would create additional hazards.
    43. Amend Sec.  23.1195 by revising the introductory text of 
paragraph (a) and by revising paragraph (a)(2) to read as follows:

[[Page 41546]]

Sec.  23.1195  Fire extinguishing systems.

    (a) For all turbojet airplanes and commuter category airplanes, 
fire extinguishing systems must be installed and compliance shown with 
the following:
* * * * *
    (2) The fire extinguishing system, the quantity of the 
extinguishing agent, the rate of discharge, and the discharge 
distribution must be adequate to extinguish fires. An individual ``one 
shot'' system may be used, except for engine(s) embedded in the 
fuselage, where a ``two-shot'' system is required.
* * * * *
    44. Amend Sec.  23.1197 by revising the introductory text to read 
as follows:


Sec.  23.1197  Fire extinguishing agents.

    For all turbojet airplanes and commuter category airplanes, the 
following applies:
* * * * *
    45. Amend Sec.  23.1199 by revising the introductory text to read 
as follows:


Sec.  23.1199  Extinguishing agent containers.

    For all turbojet airplanes and commuter category airplanes, the 
following applies:
* * * * *
    46. Amend Sec.  23.1201 by revising the introductory text to read 
as follows:


Sec.  23.1201  Fire extinguishing systems materials.

    For all turbojet airplanes and commuter category airplanes, the 
following apply:
* * * * *
    47. Revise Sec.  23.1301 by revising paragraphs (b) and (c) and by 
removing paragraph (d) to read as follows:


Sec.  23.1301  Function and installation.

* * * * *
    (b) Be labeled as to its identification, function, or operating 
limitations, or any applicable combination of these factors; and
    (c) Be installed according to limitations specified for that 
equipment.
    48. Amend Sec.  23.1303 by revising paragraph (c) to read as 
follows:


Sec.  23.1303  Flight and navigation instruments.

* * * * *
    (c) A magnetic direction indicator.
* * * * *
    49. Amend Sec.  23.1305 by adding a new paragraph (f) to read as 
follows:


Sec.  23.1305  Powerplant instruments.

* * * * *
    (f) Powerplant indicators must either provide trend or rate-of-
change information, or have the ability to:
    (1) Allow the pilot to assess necessary trend information quickly, 
including if and when this information is needed during engine restart;
    (2) Allow the pilot to assess how close the indicated parameter is 
relative to a limit;
    (3) Forewarn the pilot before the parameter reaches an operating 
limit; and
    (4) For multiengine airplanes, allow the pilot to quickly and 
accurately compare engine-to-engine data.
    50. Revise Sec.  23.1307 to read as follows:


Sec.  23.1307  Miscellaneous equipment.

    The equipment necessary for an airplane to operate at the maximum 
operating altitude and in the kinds of operations (e.g., part 91, part 
135) and meteorological conditions for which certification is requested 
and is approved in accordance with Sec.  23.1559 must be included in 
the type design.
    51. Revise Sec.  23.1309 to read as follows:


Sec.  23.1309  Equipment, systems, and installations.

    The requirements of this section, except as identified below, are 
applicable, in addition to specific design requirements of part 23, to 
any equipment or system as installed in the airplane. This section is a 
regulation of general requirements. It does not supersede any specific 
requirements contained in another section of part 23. This section 
should be used to determine software and hardware development assurance 
levels. This section does not apply to the performance, flight 
characteristics requirements of subpart B of this part, and structural 
loads and strength requirements of subparts C and D of this part, but 
it does apply to any system on which compliance with the requirements 
of subparts B, C, D, and E of this part are based. The flight structure 
such as wing, empennage, control surfaces and their simple, or simple 
and conventional systems, the fuselage, engine mounting, and landing 
gear and their related primary attachments are excluded. For example, 
it does not apply to an airplane's inherent stall characteristics or 
their evaluation of Sec.  23.201, but it does apply to a stick pusher 
(stall barrier) system installed to attain compliance with Sec.  
23.201.
    (a) The airplane equipment and systems must be designed and 
installed so that:
    (1) Those required for type certification or by operating rules, or 
whose improper functioning would reduce safety, perform as intended 
under the airplane operating and environmental conditions, including 
radio frequency energy and the effects (both direct and indirect) of 
lightning strikes.
    (2) Those required for type certification or by operating rules and 
other equipment and systems do not adversely affect the safety of the 
airplane or its occupants, or the proper functioning of those covered 
by paragraph (a)(1) of this section.
    (3) For minor, major, hazardous, or catastrophic failure 
condition(s), the results of certification testing must not be 
inconsistent with the results of the safety analysis process.
    (b) The airplane systems and associated components for the 
appropriate classes of airplane, considered separately and in relation 
to other systems, must be designed and installed so that:
    (1) Each catastrophic failure condition is extremely improbable and 
does not result from a single failure;
    (2) Each hazardous failure condition is extremely remote;
    (3) Each major failure condition is remote; and
    (4) Each failure condition meets the relationship among airplane 
classes, probabilities, severity of failure condition(s), and software 
and complex hardware development assurance levels shown in Appendix K 
of this part.
    (5) Compliance with the requirements of paragraph (b)(2) of this 
section may be shown by analysis and, where necessary, by appropriate 
ground, flight, or simulator tests. The analysis must consider--
    (i) Possible modes of failure, including malfunctions and damage 
from external sources;
    (ii) The probability of multiple failures and the probability of 
undetected faults;
    (iii) The resulting effects of the airplane and occupants, 
considering the stage of flight and operating conditions; and
    (iv) The crew warning cues, corrective action required, and the 
crew's capability of determining faults.
    (c) Functional failure condition(s) that are classified as minor do 
not require a quantitative analysis, but verification by a design and 
installation appraisal is required.
    (d) Systems with major failure condition(s)--
    (1) May be verified by a qualitative analysis, if the systems are 
simple, simple and conventional, or conventional and redundant.
    (2) Must be verified by a qualitative and quantitative analysis, if 
the systems

[[Page 41547]]

do not meet the condition(s) prescribed in paragraph (d)(1) of this 
section.
    (e) Systems with hazardous or catastrophic failure condition(s)--
    (1) May be verified by a qualitative and quantitative analysis, if 
the systems are simple and conventional.
    (2) Must be verified by a qualitative and quantitative analysis if 
the systems are not simple and conventional.
    (f) Information concerning an unsafe system operating condition(s) 
must be provided to the crew to enable them to take appropriate 
corrective action. A warning indication must be provided if immediate 
corrective action is required. Systems and controls, including 
indications and annunciations must be designed to minimize crew errors, 
which could create additional hazards.
    52. Add a new Sec.  23.1310 to read as follows:


Sec.  23.1310  Power source capacity and distribution.

    (a) Each item of equipment, each system, and each installation 
whose functioning is required by this chapter 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 power distribution system with the 
system functioning normally.
    (2) Essential loads after failure of--
    (i) Any one engine on two-engine airplanes, or
    (ii) Any two engines on an airplane with three or more engines, or
    (iii) Any power converter or energy storage device.
    (3) Essential loads for which an alternate source of power is 
required, as applicable, by the operating rules of this chapter, after 
any failure or malfunction in any one power supply system, distribution 
system, or other utilization system.
    (b) In determining compliance with paragraph (a)(2) of this 
section, the power loads may be assumed to be reduced under a 
monitoring procedure consistent with safety in the kinds of operations 
authorized. Loads not required in controlled flight need not be 
considered for the two-engine-inoperative condition on airplanes with 
three or more engines.
    53. Amend Sec.  23.1311 by revising paragraphs (a)(5), (a)(6), 
(a)(7), and paragraph (b) to read as follows:


Sec.  23.1311  Electronic display instrument systems.

    (a) * * *
    (5) Have an independent magnetic direction indicator and an 
independent secondary mechanical altimeter, airspeed indicator, and 
attitude instrument or electronic display parameters for the altitude, 
airspeed, and attitude that are independent from the airplane's primary 
electrical power system. These secondary instruments may be installed 
in panel positions that are displaced from the primary positions 
specified by Sec.  23.1321(d), but must be located where they meet the 
pilot's visibility requirements of Sec.  23.1321(a).
    (6) Incorporate sensory cues that provide a quick glance sense of 
rate and, when appropriate, trend information to the pilot.
    (7) Incorporate equivalent visual displays of the instrument 
markings required by Sec. Sec.  23.1541 through 23.1553, or visual 
displays that alert the pilot to abnormal operational values or 
approaches to established limitation values, for each parameter 
required to be displayed by this part.
    (b) The electronic display indicators, including their systems and 
installations, and considering other airplane systems, must be designed 
so that one display of information essential for continued safe flight 
and landing will be available within one second to the crew with a 
single pilot action or by automatic means for continued safe operation, 
after any single failure or probable combination of failures.
* * * * *
    54. Amend Sec.  23.1323 by revising paragraph (e) to read as 
follows:


Sec.  23.1323  Airspeed indicating system.

* * * * *
    (e) In addition, for normal, utility, and acrobatic category 
multiengine turbojet airplanes of more than 6,000 pounds maximum weight 
and commuter category airplanes, each system must be calibrated to 
determine the system error during the accelerate-takeoff ground run. 
The ground run calibration must be determined--
    (1) From 0.8 of the minimum value of V1 to the maximum 
value of V2, considering the approved ranges of altitude and 
weight, and
    (2) The ground run calibration must be determined assuming an 
engine failure at the minimum value of V1.
* * * * *
    55. Amend Sec.  23.1331 by revising paragraph (c) to read as 
follows:


Sec.  23.1331  Instruments using a power source.

* * * * *
    (c) For certification for Instrument Flight Rules (IFR) operations 
and for the heading, altitude, airspeed, and attitude, there must be at 
least:
    (1) Two independent sources of power (not driven by the same engine 
on multiengine airplanes), and a manual or an automatic means to select 
each power source; or
    (2) An additional display of parameters for heading, altitude, 
airspeed, and attitude that is independent from the airplane's primary 
electrical power system.
    56. Amend Sec.  23.1353 by revising paragraph (h) to read as 
follows:


Sec.  23.1353  Storage battery design and installation.

* * * * *
    (h) In the event of a complete loss of the primary electrical power 
generating system, the battery must be capable of providing electrical 
power to those loads that are essential to continued safe flight and 
landing for:
    (1) At least 30 minutes for airplanes that are certificated with a 
maximum altitude of 25,000 feet or less, and
    (2) At least 60 minutes for airplanes that are certificated with a 
maximum altitude over 25,000 feet.
    57. Revise Sec.  23.1443 to read as follows:


Sec.  23.1443  Minimum mass flow of supplemental oxygen.

    (a) If the airplane is to be certified above 40,000 feet, a 
continuous flow oxygen system must be provided for each passenger and 
crewmember.
    (b) If continuous flow oxygen equipment is installed, an applicant 
must show compliance with the requirements of either paragraphs (b)(1) 
and (b)(2) or paragraph (b)(3) of this section:
    (1) For each passenger, the minimum mass flow of supplemental 
oxygen required at various cabin pressure altitudes may not be less 
than the flow required to maintain, during inspiration and while using 
the oxygen equipment (including masks) provided, the following mean 
tracheal oxygen partial pressures:
    (i) At cabin pressure altitudes above 10,000 feet up to and 
including 18,500 feet, a mean tracheal oxygen partial pressure of 100mm 
Hg when breathing 15 liters per minute, Body Temperature, Pressure, 
Saturated (BTPS) and with a tidal volume of 700cc with a constant time 
interval between respirations.
    (ii) At cabin pressure altitudes above 18,500 feet up to and 
including 40,000 feet, a mean tracheal oxygen partial pressure of 
83.8mm Hg when breathing 30 liters per minute, BTPS, and with a tidal 
volume of 1,100cc with a constant time interval between respirations.

[[Page 41548]]

[GRAPHIC] [TIFF OMITTED] TP17AU09.003

    (2) For each flight crewmember, the minimum mass flow may not be 
less than the flow required to maintain, during inspiration, a mean 
tracheal oxygen partial pressure of 149mm Hg when breathing 15 liters 
per minute, BTPS, and with a maximum tidal volume of 700cc with a 
constant time interval between respirations.
    (3) The minimum mass flow of supplemental oxygen supplied for each 
user must be at a rate not less than that shown in the following figure 
for each altitude up to and including the maximum operating altitude of 
the airplane.
    (c) If demand equipment is installed for use by flight crewmembers, 
the minimum mass flow of supplemental oxygen required for each flight 
crewmember may not be less than the flow required to maintain, during 
inspiration, a mean tracheal oxygen partial pressure of 122mm Hg up to 
and including a cabin pressure altitude of 35,000 feet, and 95 percent 
oxygen between cabin pressure altitudes of 35,000 and 40,000 feet, when 
breathing 20 liters per minutes BTPS. In addition, there must be means 
to allow the crew to use undiluted oxygen at their discretion.
    (d) If first-aid oxygen equipment is installed, the minimum mass 
flow of oxygen to each user may not be less than 4 liters per minute, 
STPD. However, there may be a means to decrease this flow to not less 
than 2 liters per minute, STPD, at any cabin altitude. The quantity of 
oxygen required is based upon an average flow rate of 3 liters per 
minute per person for whom first-aid oxygen is required.
    (e) As used in this section:
    (1) BTPS means Body Temperature, and Pressure, Saturated (which is 
37 [deg]C, and the ambient pressure to which the body is exposed, minus 
47mm Hg, which is the tracheal pressure displaced by water vapor 
pressure when the breathed air becomes saturated with water vapor at 37 
[deg]C).
    (2) STPD means Standard Temperature and Pressure, Dry (which is 0 
[deg]C at 760mm Hg with no water vapor).
    58. Amend Sec.  23.1445 by adding a new paragraph (c) to read as 
follows:


Sec.  23.1445  Oxygen distribution system.

* * * * *
    (c) If the flight crew and passengers share a common source of 
oxygen, a means to separately reserve the minimum supply required by 
the flight crew must be provided.
    59. Amend Sec.  23.1447 by adding a new paragraph (g) to read as 
follows:


Sec.  23.1447  Equipment standards for oxygen dispensing units.

* * * * *
    (g) If the airplane is to be certified for operation above 40,000 
feet, a quick-donning oxygen mask system, with a pressure demand, mask 
mounted regulator must be provided for the flight crew. This dispensing 
unit must be immediately available to the flight crew when seated at 
their station and installed so that it:
    (1) Can be placed on the face from its ready position, properly 
secured, sealed, and supplying oxygen upon demand, with one hand, 
within five seconds and without disturbing eyeglasses or causing delay 
in proceeding with emergency duties, and
    (2) Allows, while in place, the performance of normal communication 
functions.
    60. Amend Sec.  23.1505 by revising paragraph (c) to read as 
follows:


Sec.  23.1505  Airspeed limitations.

* * * * *
    (c) Paragraphs (a) and (b) of this section do not apply to turbine 
airplanes or the airplanes for which a design diving speed 
VD/MD is established under Sec.  23.335(b)(4). 
For those airplanes, a maximum operating limit speed (VMO/
MMO airspeed or Mach number, whichever is critical at a 
particular altitude) must be established as a speed that may not be 
deliberately exceeded in any regime of flight (climb, cruise, or 
descent) unless a higher speed is authorized for flight test or pilot 
training operations. VMO/MMO must be established 
so that it is not greater than the design cruising speed VC/
MC and so that it is sufficiently below VD/
MD, or VDF/MDF for turbojets, and the 
maximum speed shown under Sec.  23.251 to make it highly improbable 
that the latter speeds will be inadvertently exceeded in operations. 
The speed margin between VMO/MMO and 
VD/MD,

[[Page 41549]]

or VDF/MDF for turbojets, may not be less than 
that determined under Sec.  23.335(b), or the speed margin found 
necessary in the flight tests conducted under Sec.  23.253.
    61. Revise Sec.  23.1525 to read as follows:


Sec.  23.1525  Kinds of operation.

    The kinds of operation authorized (e.g., VFR, IFR, day, night, part 
91, part 135) and the meteorological conditions (e.g., icing) to which 
the operation of the airplane is limited or from which it is 
prohibited, must be established appropriate to the installed equipment.
    62. Amend Sec.  23.1545 by revising paragraph (d) to read as 
follows:


Sec.  23.1545  Airspeed indicator.

* * * * *
    (d) Paragraphs (b)(1) through (b)(4) and paragraph (c) of this 
section do not apply to airplanes for which a maximum operating speed 
VMO/MMO is established under Sec.  23.1505(c). 
For those airplanes, there must either be a maximum allowable airspeed 
indication showing the variation of VMO/MMO with 
altitude or compressibility limitations (as appropriate), or a radial 
red line marking for VMO/MMO must be made at the 
lowest value of VMO/MMO established for any 
altitude up to the maximum operating altitude for the airplane.
    63. Amend Sec.  23.1555 by adding a new paragraph (d)(3) to read as 
follows:


Sec.  23.1555  Control markings.

* * * * *
    (d) * * *
    (3) For fuel systems having a calibrated fuel quantity indication 
system complying with Sec.  23.1337(b)(1) and accurately displaying the 
actual quantity of usable fuel in each selectable tank, no fuel 
capacity placards outside of the fuel quantity indicator are required.
* * * * *
    64. Amend Sec.  23.1559 by adding a new paragraph (d) to read as 
follows:


Sec.  23.1559  Operating limitations placard.

* * * * *
    (d) The placard(s) required by this section need not be lighted.
    65. Amend Sec.  23.1563 by adding a new paragraph (d) to read as 
follows:


Sec.  23.1563  Airspeed placards.

* * * * *
    (d) The airspeed placard required by this section need not be 
lighted if the landing gear operating speed is indicated on the 
airspeed indicator or other lighted area such as the landing gear 
control and the airspeed indicator has features such as low speed 
awareness that provide ample warning prior to VMC.
    66. Amend Sec.  23.1567 by adding a new paragraph (e) to read as 
follows:


Sec.  23.1567  Flight maneuver placard.

* * * * *
    (e) The placards required by this section need not be lighted.
    67. Amend Sec.  23.1583 as follows:
    a. Revise the introductory text of paragraphs (c)(3) and (c)(4);
    b. Redesignate paragraphs (c)(4)(iii) and (c)(4)(iv) as paragraphs 
(c)(4)(ii)(A) and (c)(4)(ii)(B); and
    c. Revise paragraph (c)(5) introductory text to read as follows:


Sec.  23.1583  Operating limitations.

* * * * *
    (c) * * *
    (3) For reciprocating engine-powered airplanes of more than 6,000 
pounds maximum weight, single-engine turbines, and multiengine turbine 
airplanes 6,000 pounds or less maximum weight in the normal, utility, 
and acrobatic category, performance operating limitations as follows--
* * * * *
    (4) For normal, utility, and acrobatic category multiengine 
turbojet powered airplanes over 6,000 pounds and commuter category 
airplanes, the maximum takeoff weight for each airport altitude and 
ambient temperature within the range selected by the applicant at 
which--
* * * * *
    (5) For normal, utility, and acrobatic category multiengine 
turbojet powered airplanes over 6,000 pounds and commuter category 
airplanes, the maximum landing weight for each airport altitude within 
the range selected by the applicant at which--
* * * * *
    68. Amend Sec.  23.1585 by revising paragraph (f) introductory text 
to read as follows:


Sec.  23.1585  Operating procedures.

* * * * *
    (f) In addition to paragraphs (a) and (c) of this section, for 
normal, utility, and acrobatic category multiengine turbojet powered 
airplanes over 6,000 pounds, and commuter category airplanes, the 
information must include the following:
* * * * *
    69. Amend Sec.  23.1587 by revising paragraph (d) introductory text 
to read as follows:


Sec.  23.1587  Performance information.

* * * * *
    (d) In addition to paragraph (a) of this section, for normal, 
utility, and acrobatic category multiengine turbojet powered airplanes 
over 6,000 pounds, and commuter category airplanes, the following 
information must be furnished--
* * * * *
    70. Amend Appendix F to Part 23 by:
    a. Redesignating the existing text as Part I and adding a new Part 
I heading;
    b. Removing the introductory paragraph; and
    c. Adding a new Part II.
    The additions read as follows:

APPENDIX F TO PART 23--TEST PROCEDURE

Part I--Acceptable Test Procedure for Self-Extinguishing Materials for 
Showing Compliance With Sec. Sec.  23.853, 23.855 and 23.1359

* * * * *

Part II--Test Method To Determine the Flammability and Flame 
Propagation Characteristics of Thermal/Acoustic Insulation Materials

    Use this test method to evaluate the flammability and flame 
propagation characteristics of thermal/acoustic insulation when 
exposed to both a radiant heat source and a flame.
    (a) Definitions.
    ``Flame propagation'' means the furthest distance of the 
propagation of visible flame towards the far end of the test 
specimen, measured from the midpoint of the ignition source flame. 
Measure this distance after initially applying the ignition source 
and before all flame on the test specimen is extinguished. The 
measurement is not a determination of burn length made after the 
test.
    ``Radiant heat source'' means an electric or air propane panel.
    ``Thermal/acoustic insulation'' means a material or system of 
materials used to provide thermal and/or acoustic protection. 
Examples include fiberglass or other batting material encapsulated 
by a film covering and foams.
    ``Zero point'' means the point of application of the pilot 
burner to the test specimen.
    (b) Test apparatus.

[[Page 41550]]

[GRAPHIC] [TIFF OMITTED] TP17AU09.004

    (1) Radiant panel test chamber. Conduct tests in a radiant panel 
test chamber (see figure F1 above). Place the test chamber under an 
exhaust hood to facilitate clearing the chamber of smoke after each 
test. The radiant panel test chamber must be an enclosure 55 inches 
(1397 mm) long by 19.5 (495 mm) deep by 28 (710 mm) to 30 inches 
(maximum) (762 mm) above the test specimen. Insulate the sides, 
ends, and top with a fibrous ceramic insulation, such as Kaowool MTM 
board. On the front side, provide a 52 by 12-inch (1321 by 305 mm) 
draft-free, high-temperature, glass window for viewing the sample 
during testing. Place a door below the window to provide access to 
the movable specimen platform holder. The bottom of the test chamber 
must be a sliding steel platform that has provision for securing the 
test specimen holder in a fixed and level position. The chamber must 
have an internal chimney with exterior dimensions of 5.1 inches (129 
mm) wide, by 16.2 inches (411 mm) deep by 13 inches (330 mm) high at 
the opposite end of the chamber from the radiant energy source. The 
interior dimensions must be 4.5 inches (114 mm) wide by 15.6 inches 
(395 mm) deep. The chimney must extend to the top of the chamber 
(see figure F2).
[GRAPHIC] [TIFF OMITTED] TP17AU09.005

    (2) Radiant heat source. Mount the radiant heat energy source in 
a cast iron frame or equivalent. An electric panel must have six, 3-
inch wide emitter strips. The emitter strips must be perpendicular 
to the length of the panel. The panel must have a radiation surface 
of 12 \7/8\ by 18 \1/2\ inches (327 by 470 mm). The panel must be 
capable of operating at temperatures up to 1300 [deg]F (704 [deg]C). 
An air propane panel must be made of a porous refractory material 
and have a radiation surface of 12 by 18 inches (305 by 457 mm). The 
panel must be capable of operating at temperatures up to 1,500 
[deg]F (816 [deg]C). See figures 3a and 3b.

[[Page 41551]]

[GRAPHIC] [TIFF OMITTED] TP17AU09.006

    (i) Electric radiant panel. The radiant panel must be 3-phase 
and operate at 208 volts. A single-phase, 240 volt panel is also 
acceptable. Use a solid-state power controller and microprocessor-
based controller to set the electric panel operating parameters.
    (ii) Gas radiant panel. Use propane (liquid petroleum gas--2.1 
UN 1075) for the radiant panel fuel. The panel fuel system must 
consist of a venturi-type aspirator for mixing gas and air at 
approximately atmospheric pressure. Provide suitable instrumentation 
for monitoring and controlling the flow of fuel and air to the 
panel. Include an air flow gauge, an air flow regulator, and a gas 
pressure gauge.
    (iii) Radiant panel placement. Mount the panel in the chamber at 
30 degrees to the horizontal specimen plane, and 7\1/2\ inches above 
the zero point of the specimen.
    (3) Specimen holding system.
    (i) The sliding platform serves as the housing for test specimen 
placement. Brackets may be attached (via wing nuts) to the top lip 
of the platform in order to accommodate various thicknesses of test 
specimens. Place the test specimens on a sheet of Kaowool MTM board 
or 1260 Standard Board (manufactured by Thermal Ceramics and 
available in Europe), or equivalent, either resting on the bottom 
lip of the sliding platform or on the base of the brackets. It may 
be necessary to use multiple sheets of material based on the 
thickness of the test specimen (to meet the sample height 
requirement). Typically, these non-combustible sheets of material 
are available in \1/4\ inch (6 mm) thicknesses. See figure F4. A 
sliding platform that is deeper than the 2-

[[Page 41552]]

inch (50.8 mm) platform shown in figure F4 is also acceptable as 
long as the sample height requirement is met.
[GRAPHIC] [TIFF OMITTED] TP17AU09.007

    (ii) Attach a \1/2\ inch (13 mm) piece of Kaowool MTM board or 
other high temperature material measuring 41\1/2\ by 8\1/4\ inches 
(1054 by 210 mm) to the back of the platform. This board serves as a 
heat retainer and protects the test specimen from excessive 
preheating. The height of this board must not impede the sliding 
platform movement (in and out of the test chamber). If the platform 
has been fabricated such that the back side of the platform is high 
enough to prevent excess preheating of the specimen when the sliding 
platform is out, a retainer board is not necessary.
    (iii) Place the test specimen horizontally on the non-
combustible board(s). Place a steel retaining/securing frame 
fabricated of mild steel, having a thickness of \1/8\ inch (3.2 mm) 
and overall dimensions of 23 by 13\1/8\ inches (584 by 333 mm) with 
a specimen opening of 19 by 10\3/4\ inches (483 by 273 mm) over the 
test specimen. The front, back, and right portions of the top flange 
of the frame must rest on the top of the sliding platform, and the 
bottom flanges must pinch all 4 sides of the test specimen. The 
right bottom flange must be flush with the sliding platform. See 
figure F5.
[GRAPHIC] [TIFF OMITTED] TP17AU09.008


[[Page 41553]]


    (4) Pilot Burner. The pilot burner used to ignite the specimen 
must be a BernzomaticTM commercial propane venturi torch with an 
axially symmetric burner tip and a propane supply tube with an 
orifice diameter of 0.006 inches (0.15 mm). The length of the burner 
tube must be 2\7/8\ inches (71 mm). The propane flow must be 
adjusted via gas pressure through an in-line regulator to produce a 
blue inner cone length of \3/4\ inch (19 mm). A \3/4\ inch (19 mm) 
guide (such as a thin strip of metal) may be soldered to the top of 
the burner to aid in setting the flame height. The overall flame 
length must be approximately 5 inches long (127 mm). Provide a way 
to move the burner out of the ignition position so that the flame is 
horizontal and at least 2 inches (50 mm) above the specimen plane. 
See figure F6.
[GRAPHIC] [TIFF OMITTED] TP17AU09.009

    (5) Thermocouples. Install a 24 American Wire Gauge (AWG) Type K 
(Chromel- Alumel) thermocouple in the test chamber for temperature 
monitoring. Insert it into the chamber through a small hole drilled 
through the back of the chamber. Place the thermocouple so that it 
extends 11 inches (279 mm) out from the back of the chamber wall, 
11\1/2\ inches (292 mm) from the right side of the chamber wall, and 
is 2 inches (51 mm) below the radiant panel. The use of other 
thermocouples is optional.
    (6) Calorimeter. The calorimeter must be a one-inch cylindrical 
water-cooled, total heat flux density, foil type Gardon Gage that 
has a range of 0 to 5 BTU/ft\2\ -second (0 to 5.7 Watts/cm\2\).
    (7) Calorimeter calibration specification and procedure.
    (i) Calorimeter specification.
    (A) Foil diameter must be 0.25  0.005 inches (6.35 
 0.13 mm).
    (B) Foil thickness must be 0.0005  0.0001 inches 
(0.013  0.0025 mm).
    (C) Foil material must be thermocouple grade Constantan.
    (D) Temperature measurement must be a Copper Constantan 
thermocouple.
    (E) The copper center wire diameter must be 0.0005 inches (0.013 
mm).
    (F) The entire face of the calorimeter must be lightly coated 
with ``Black Velvet'' paint having an emissivity of 96 or greater.
    (ii) Calorimeter calibration.
    (A) The calibration method must be by comparison to a like 
standardized transducer.
    (B) The standardized transducer must meet the specifications 
given in paragraph VI(b)(6) of this appendix.
    (C) Calibrate the standard transducer against a primary standard 
traceable to the National Institute of Standards and Technology 
(NIST).
    (D) The method of transfer must be a heated graphite plate.
    (E) The graphite plate must be electrically heated, have a clear 
surface area on each side of the plate of at least 2 by 2 inches (51 
by 51 mm), and be \1/8\ inch  \1/16\ inch thick (3.2 
 1.6 mm).
    (F) Center the 2 transducers on opposite sides of the plates at 
equal distances from the plate.
    (G) The distance of the calorimeter to the plate must be no less 
than 0.0625 inches (1.6 mm), nor greater than 0.375 inches (9.5 mm).
    (H) The range used in calibration must be at least 0-3.5 BTUs/
ft\2\ second (0-3.9 Watts/cm\2\) and no greater than 0-5.7 BTUs/
ft\2\ second (0-6.4 Watts/cm\2\).
    (I) The recording device used must record the 2 transducers 
simultaneously or at least within \1/10\ of each other.
    (8) Calorimeter fixture. With the sliding platform pulled out of 
the chamber, install the calorimeter holding frame and place a sheet 
of non-combustible material in the bottom of the sliding platform 
adjacent to the holding frame. This will prevent heat losses during 
calibration. The frame must be 13\1/8\ inches (333 mm) deep (front 
to back) by 8 inches (203 mm) wide and must rest on the top of the 
sliding platform. It must be fabricated of \1/8\ inch (3.2 mm) flat 
stock steel and have an opening that accommodates a \1/2\ inch (12.7 
mm) thick piece of refractory board, which is level with the top of 
the sliding platform. The board must have three 1-inch (25.4 mm) 
diameter holes drilled through the board for calorimeter insertion. 
The distance to the radiant panel surface from the centerline of the 
first hole (``zero'' position) must be 7\1/2\  \1/8\ 
inches (191  3 mm). The distance between the centerline 
of the first hole to the centerline of the second hole must be 2 
inches (51 mm). It must also be the same distance from the 
centerline of the second hole to the centerline of the third hole. 
See figure F7. A calorimeter holding frame that differs in 
construction is acceptable as long as the height from the centerline 
of the first hole to the radiant panel and the distance between 
holes is the same as described in this paragraph.

[[Page 41554]]

[GRAPHIC] [TIFF OMITTED] TP17AU09.010

    (9) Instrumentation. Provide a calibrated recording device with 
an appropriate range or a computerized data acquisition system to 
measure and record the outputs of the calorimeter and the 
thermocouple. The data acquisition system must be capable of 
recording the calorimeter output every second during calibration.
    (10) Timing device. Provide a stopwatch or other device, 
accurate to  1 second/hour, to measure the time of 
application of the pilot burner flame.
    (c) Test specimens.
    (1) Specimen preparation. Prepare and test a minimum of three 
test specimens. If an oriented film cover material is used, prepare 
and test both the warp and fill directions.
    (2) Construction. Test specimens must include all materials used 
in construction of the insulation (including batting, film, scrim, 
tape, etc.). Cut a piece of core material such as foam or 
fiberglass, and cut a piece of film cover material (if used) large 
enough to cover the core material. Heat sealing is the preferred 
method of preparing fiberglass samples, since they can be made 
without compressing the fiberglass (``box sample''). Cover materials 
that are not heat sealable may be stapled, sewn, or taped as long as 
the cover material is over-cut enough to be drawn down the sides 
without compressing the core material. The fastening means should be 
as continuous as possible along the length of the seams. The 
specimen thickness must be of the same thickness as installed in the 
airplane.
    (3) Specimen Dimensions. To facilitate proper placement of 
specimens in the sliding platform housing, cut non-rigid core 
materials, such as fiberglass, 12\1/2\ inches (318 mm) wide by 23 
inches (584 mm) long. Cut rigid materials, such as foam, 11\1/2\ 
 \1/4\ inches (292 mm  6 mm) wide by 23 
inches (584 mm) long in order to fit properly in the sliding 
platform housing and provide a flat, exposed surface equal to the 
opening in the housing.
    (d) Specimen conditioning. Condition the test specimens at 70 
 5 [deg]F (21  2 [deg]C) and 55 percent 
 10 percent relative humidity, for a minimum of 24 hours 
prior to testing.
    (e) Apparatus Calibration.
    (1) With the sliding platform out of the chamber, install the 
calorimeter holding frame. Push the platform back into the chamber 
and insert the calorimeter into the first hole (``zero'' position). 
See figure F7. Close the bottom door located below the sliding 
platform. The distance from the centerline of the calorimeter to the 
radiant panel surface at this point must be 7\1/2\ inches  \1/8\ (191 mm  3). Before igniting the radiant 
panel, ensure that the calorimeter face is clean and that there is 
water running through the calorimeter.
    (2) Ignite the panel. Adjust the fuel/air mixture to achieve 1.5 
BTUs/feet\2\ -second  5 percent (1.7 Watts/cm\2\  5 percent) at the ``zero'' position. If using an electric 
panel, set the power controller to achieve the proper heat flux. 
Allow the unit to reach steady state (this may take up to 1 hour). 
The pilot burner must be off and in the down position during this 
time.
    (3) After steady-state conditions have been reached, move the 
calorimeter 2 inches (51 mm) from the ``zero'' position (first hole) 
to position 1 and record the heat flux. Move the calorimeter to 
position 2 and record the heat flux. Allow enough time at each 
position for the calorimeter to stabilize. Table 1 depicts typical 
calibration values at the three positions.

                       Table 1--Calibration Table
------------------------------------------------------------------------
            Position               BTU's/feet\2\ sec      Watts/cm\2\
------------------------------------------------------------------------
``Zero'' Position...............                 1.5                 1.7
Position 1......................      1.51-1.50-1.49      1.71-1.70-1.69
Position 2......................           1.43-1.44           1.62-1.63
------------------------------------------------------------------------

     (4) Open the bottom door, remove the calorimeter and holder 
fixture. Use caution as the fixture is very hot.
    (f) Test Procedure.
    (1) Ignite the pilot burner. Ensure that it is at least 2 inches 
(51 mm) above the top of the platform. The burner must not contact 
the specimen until the test begins.
    (2) Place the test specimen in the sliding platform holder. 
Ensure that the test sample surface is level with the top of the 
platform. At ``zero'' point, the specimen surface must be 7\1/2\ 
inches  \1/8\ inch (191 mm  3) below the 
radiant panel.
    (3) Place the retaining/securing frame over the test specimen. 
It may be necessary (due to compression) to adjust the sample (up or 
down) in order to maintain the distance from the sample to the 
radiant panel (7\1/2\ inches  \1/8\ inch (191 mm  3) at ``zero'' position). With film/fiberglass assemblies, it 
is critical to make a slit in the film cover to purge any air 
inside. This allows the operator to maintain the proper test 
specimen position (level with the top of the platform) and to allow 
ventilation of gases during testing. A longitudinal slit, 
approximately 2 inches (51 mm) in length, must be centered 3 inches 
 \1/2\ inch (76 mm  13 mm) from the left 
flange of the securing frame. A utility knife is acceptable for 
slitting the film cover.
    (4) Immediately push the sliding platform into the chamber and 
close the bottom door.

[[Page 41555]]

    (5) Bring the pilot burner flame into contact with the center of 
the specimen at the ``zero'' point and simultaneously start the 
timer. The pilot burner must be at a 27 degree angle with the sample 
and be approximately \1/2\ inch (12 mm) above the sample. See figure 
F7. A stop, as shown in figure F8, allows the operator to position 
the burner correctly each time.
[GRAPHIC] [TIFF OMITTED] TP17AU09.011

    (6) Leave the burner in position for 15 seconds and then remove 
to a position at least 2 inches (51 mm) above the specimen.
    (g) Report.
    (1) Identify and describe the test specimen.
    (2) Report any shrinkage or melting of the test specimen.
    (3) Report the flame propagation distance. If this distance is 
less than 2 inches, report this as a pass (no measurement required).
    (4) Report the after-flame time.
    (h) Requirements.
    (1) There must be no flame propagation beyond 2 inches (51 mm) 
to the left of the centerline of the pilot flame application.
    (2) The flame time after removal of the pilot burner may not 
exceed 3 seconds on any specimen.
    71. Add a new Appendix K to part 23 to read as follows:

Appendix K to Part 23--Relationship Among Airplane Classes, 
Probabilities, Severity of Failure Conditions, and Software and Complex 
Hardware Development Assurance Levels

--------------------------------------------------------------------------------------------------------------------------------------------------------
 
--------------------------------------------------------------------------------------------------------------------------------------------------------
     Classification of failure          No safety effect              Minor                  Major                Hazardous             Catastrophic
             conditions
--------------------------------------------------------------------------------------------------------------------------------------------------------
 Allowable qualitative probability       No probability             Probable                 Remote            Extremely remote     Extremely improbable
                                           requirement
--------------------------------------------------------------------------------------------------------------------------------------------------------
Effect on Airplane.................  No effect on            Slight reduction in     Significant reduction  Large reduction in     Normally with hull
                                      operational             functional              in functional          functional             loss.
                                      capabilities or         capabilities or         capabilities or        capabilities or
                                      safety.                 safety margins.         safety margins.        safety margins.
Effect on Occupants................  Inconvenience for       Physical discomfort     Physical distress to   Serious or fatal       Multiple fatalities
                                      passengers.             for passengers.         passengers, possibly   injury to an
                                                                                      including injuries.    occupant.
Effect on Flight Crew..............  No effect on flight     Slight increase in      Physical discomfort    Physical distress or   Fatal Injury or
                                      crew.                   workload or use of      or a significant       excessive workload     incapacitation.
                                                              emergency procedures.   increase in workload.  impairs ability to
                                                                                                             perform tasks.
--------------------------------------------------------------------------------------------------------------------------------------------------------
        Classes of Airplanes         Allowable Quantitative Probabilities and Software (SW) and Complex Hardware (HW) Development Assurance Levels (Note
                                                                                              2)
--------------------------------------------------------------------------------------------------------------------------------------------------------
              Class I
(Typically SRE under 6,000).                                 HW Development                                  P=C, S=D.              S=D.                   S=C.
                                      Assurance Levels
                                      Requirement.
              Class II
(Typically MRE, STE, or MTE under    No Probability or SW &  <10-3, Note 1, P=D....  <10-5, Notes 1 & 4,    <10-6, Notes 4, P=C,   <10-7, Note 3, P=C,
 6,000).                     HW Development                                  P=C, S=D.              S=C.                   S=C.
                                      Assurance Levels
                                      Requirement.

[[Page 41556]]

 
             Class III
(Typically SRE, STE, MRE, & MTE      No Probability or SW &  <10-3, Note 1, P=D....  <10-5, Notes 1 & 4,    <10-7, Notes 4, P=C,   <10-8, Note 3, P=B,
 equal or over 6,000).       HW Development                                  P=C, S=D.              S=C.                   S=C.
                                      Assurance Levels
                                      Requirement.
              Class IV
(Typically Commuter Category)......  No Probability or SW &  <10-3, Note 1, P=D....  <10-5, Notes 1 & 4,    <10-7, Notes 4, P=B,   <10-9, Note 3, P=A,
                                      HW Development                                  P=C, S=D.              S=C.                   S=B.
                                      Assurance Levels
                                      Requirement.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note 1: Numerical values indicate an order of probability range and are provided here as a reference.
Note 2: The alphabets denote the typical SW and HW Development Assurance Levels for Primary System (P) and Secondary System (S). For example, HW or SW
  Development Assurance Level A on Primary System is noted by P=A.
Note 3: At airplane function level, no single failure will result in a Catastrophic Failure Condition.
Note 4: Secondary System (S) may not be required to meet probability goals. If installed, S must meet stated criteria.
Acronyms: SRE--single, reciprocating engine, MRE--multiple, reciprocating engines, STE--single, turbine engine, MTE--multiple, turbine engines, SW--
  software, HW--hardware.


    Issued in Washington, DC, on August 6, 2009.
Dorenda D. Baker,
Director, Aircraft Certification Service, Office of Aviation Safety.
[FR Doc. E9-19350 Filed 8-14-09; 8:45 am]
BILLING CODE 4910-13-P