[Federal Register Volume 76, Number 232 (Friday, December 2, 2011)]
[Rules and Regulations]
[Pages 75736-75769]
[FR Doc No: 2011-30412]

Vol. 76

Friday,

No. 232

December 2, 2011

Part IV

Department of Transportation

-----------------------------------------------------------------------

Federal Aviation Administration

-----------------------------------------------------------------------

14 CFR Part 23

Certification of Part 23 Turbofan- and Turbojet-Powered Airplanes and
Miscellaneous Amendments; Final Rule

Federal Register / Vol. 76 , No. 232 / Friday, December 2, 2011 /
Rules and Regulations

-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 23

[Docket No. FAA-2009-0738; Amendment No. 23-62]
RIN 2120-AJ22

Certification of Part 23 Turbofan- and Turbojet-Powered Airplanes
and Miscellaneous Amendments

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: This action enhances safety by amending the applicable
standards for part 23 turbofan- and turbojet-powered airplanes--which
are commonly referred to as ``part 23 jets,'' or ``jets''--as well as
turbopropeller-driven and reciprocating-engine airplanes, 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 level of safety findings
necessary to certificate jets. The effect of the changes will: Enhance
safety by requiring additional battery endurance requirements; increase
the climb gradient performance for certain part 23 airplanes;
standardize and simplify the certification of jets; clarify areas of
frequent non-standardization and misinterpretation, particularly for
electronic equipment and system certification; and codify existing
certification requirements in special conditions for jets that
incorporate new technologies.

DATES: These amendments become effective January 31, 2012.

FOR FURTHER INFORMATION CONTACT: For technical questions concerning
this final rule, contact Pat Mullen, Regulations and Policy, ACE-111,
Federal Aviation Administration, 901 Locust Street, Kansas City, MO
64106; telephone:<PHONE_NUMBER>; facsimile:<PHONE_NUMBER>; email:
<EMAIL_ADDRESS>For legal questions concerning this final rule,
contact Mary Ellen Loftus, ACE-7, Federal Aviation Administration, 901
Locust Street, Kansas City, MO 64106; telephone:<PHONE_NUMBER>; email:
<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION:

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. Aviation Rulemaking Committee (ARC) Recommendations
    B. Summary of the Notice of Proposed Rulemaking
    C. Summary of the Final Rule
    D. Summary of the Comments
II. Discussion of the Final Rule
    A. 14 CFR Part 1: Clarifying Power and Engine Definitions
    B. Expanding Commuter Category To Include Turbojets
    C. Performance, Flight Characteristics, and Other Design
Considerations
    D. Structural Considerations for Crashworthiness and High-
Altitude Operations
    E. Powerplant and Operational Considerations
    F. General Fire Protection and Flammability Standards for
Insulation Materials
    G. Additional Powerplant and Operational Considerations
    H. Additional Powerplant Fire Protection and Flammability
Standards
    I. Avionics, Systems, and Equipment Changes
    J. Placards, Operating Limitations, and Information
    K. Test Procedures and Appendices
III. Regulatory Analyses

I. Background

A. Aviation Rulemaking Committee (ARC) Recommendations

    On February 3, 2003, we published a notice announcing the creation
of the part 125/135 Aviation Rulemaking Committee (68 FR 5488). The ARC
completed its work in 2005 and submitted its recommendations to the FAA
for safety standards applicable to part 23 turbojets. The ARC
recommended modifying forty-one 14 CFR part 23 sections as a result of
its review of these areas. Those documents may be reviewed in the
docket for this final rule.
    The safety standards are to reflect the current 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 purposes. In addition, the ARC reviewed the
special conditions applied to part 23 turbojets.
    Based on those ARC recommendations, the FAA's intent is to enhance
safety and 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 weighing more than 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
the proposed rulemaking in accordance with them. The two
recommendations we disagreed with would have lowered the standards
previously applied through special conditions.

B. Summary of the Notice of Proposed Rulemaking

    The FAA issued the notice of proposed rulemaking (NPRM),
``Certification of Turbojets,'' on August 6, 2009 and published it for
public comment on August 17, 2009 (74 FR 41556). The comment period for
the NPRM closed on December 16, 2009 after a one-month extension.
    The FAA proposed the adoption of 67 new or revised amendments in
the NPRM. The amendments were proposed to codify previous certification
activity.

C. Summary of the Final Rule

    This final rule adopts 59 of the 67 proposed amendments. We have
also amended Sec. Sec.  23.65 and 23.1431 in this final rule based on
comments received. Changes to Sec.  23.65 make it consistent with the
changes made to Sec.  23.63. Editorial changes to Sec.  23.1431 are
based on paragraph designation changes to Sec.  23.1309.
    This final rule mainly levies new regulations for part 23 jets.
These new

regulations generally fall into the following categories:

 Airplane flight performance and stability
 Airplane structural and cabin environment
 Airplane avionics systems and electrical equipment
 Powerplant considerations
 Flammability standards

    The majority of this final rule allows manufacturers of jets to
achieve product certification without the numerous special conditions,
equivalent level of safety (ELOS) findings, and exemptions previously
required to certificate these products. Therefore, this final rule
reduces the certification burden on the applicant and allows the FAA to
focus resources on other safety-critical items. In addition, this final
rule enhances safety by requiring additional battery endurance
requirements and increasing the climb gradient performance for certain
part 23 airplanes.

D. Summary of the Comments

    The FAA received 244 substantive comments from 14 commenters. All
of the commenters generally supported the proposed changes. The
comments included suggested changes, which are discussed more fully
below in Section II, Discussion of the Final Rule.
    The FAA received no comments on the following sections, and they
are adopted as proposed or with minor editorial changes:

 23.77, Balked landing
 23.853(d)(2), Passenger and crew compartment interiors
 23.1303(c), Flight and navigation instruments
 23.1445, Oxygen distribution system
 23.1447, Equipment standards for oxygen dispensing units
 23.1545, Airspeed indicator
 23.1555, Control markings
 23.1559, Operating limitations placard
 23.1563, Airspeed placards
 23.1567, Flight maneuver placard

    The FAA received comments from manufacturers, foreign aviation
authorities, and industry associations. No commenters recommended
withdrawing the NPRM. Most of the commenters provided suggestions for
improvement or requested clarification of specific proposed amendments.
Some commenters recommended that several proposed amendments (or
portions of them) not be adopted. However, objection to one proposed
amendment did not equate to overall objection to the NPRM.
    The following areas are the key concerns expressed by industry:

 Mandating software and complex hardware development assurance
levels
 Requirement for electronic engine controls to meet the
requirements of Sec.  23.1309 ``Equipment, systems and installations''
 Subpart B, Flight, and Subpart G, Operating Limitations and
Information
 Requirement for ``two shot'' fire extinguishing systems for
engines embedded within the fuselage
 Codifying high-altitude operations
 Requirements for electronic displays in part 23 airplanes
 Part 1 definitions (Sec.  1.1)

    The FAA also received comments regarding FAA policy, means of
compliance, and suggested changes to advisory circulars and regulations
not included in the NPRM. These comments are considered to be beyond
the scope of this rulemaking effort. No further discussion of them
occurs in this final rule.

II. Discussion of the Final Rule

A. 14 CFR Part 1: Clarifying Power and Engine Definitions

    The FAA proposed to amend Sec.  1.1 definitions for ``rated takeoff
power,'' ``rated takeoff thrust,'' ``turbine engine,'' ``turbojet
engine,'' and ``turboprop engine.'' Defining engine-specific terms was
proposed to clarify the new requirements in part 23. Communications
between the FAA and members of industry indicated a need to define
those terms. These communications were mainly based on current part 1
definitions for ``rated takeoff power'' and ``rated takeoff thrust,''
which currently limit the use of power and thrust ratings to no more
than five minutes for takeoff operation.
    The FAA received comments from Rolls Royce, Transport Canada,
General Electric (GE), and the European Aviation Safety Agency (EASA)
objecting to the proposed definitions. The FAA agrees with the
commenters that ``rated takeoff power,'' ``rated takeoff thrust,''
``turbine engine,'' ``turbojet engine,'' and ``turboprop engine'' are
not used consistently in Title 14, Code of Federal Regulations (14
CFR).
    Defining engine types--whether turbine-powered (turbine), turbojet-
powered (turbojet), or turbopropeller-driven (turboprop)--is
unnecessary because they are commonly understood by those within
industry. However, the commenters make a valid point regarding changes
to the definitions for ``rated takeoff power'' and ``rated takeoff
thrust.'' These terms may not necessarily be accepted for use in part
25, and as such, should not be defined under Sec.  1.1.
    The Engine and Propeller Directorate is currently working to
establish common definitions for ``rated takeoff power'' and ``rated
takeoff thrust'' that would apply to both part 23 and part 25
airplanes. The proposals to add these definitions are withdrawn to
allow the Engine and Propeller Directorate time to complete its work on
this effort.

B. Expanding Commuter Category to Include Jets

    The FAA proposed to revise Sec.  23.3 to codify the current FAA
practice of certificating multiengine jets weighing up to and including
19,000 pounds under part 23 in the commuter category. Prior amendments
to part 23 limited Sec.  23.3 commuter category to propeller-driven,
multiengine airplanes weighing no more than 19,000 pounds. However, the
FAA issued exemptions to allow jets weighing more than 12,500 pounds to
be certificated under part 23, commuter category.
    The FAA received comments from Transport Canada and EASA. Transport
Canada proposed that jets with seating capacity of 10 or more
(excluding pilot seats), or maximum certificated take-off weight of
more than 12,500 pounds, continue to be certificated using part 25
transport category requirements in Subpart B: Performance. EASA
suggested the rule pertain to ``high performance'' rather than
``multiengine'' airplanes.
    The FAA did not adopt either comment. Transport Canada's comment
was not adopted because part 23, Subpart B has been shown to be an
acceptable means of compliance for airplanes weighing up to 19,000
pounds. This final rule retains that weight limit. EASA's comment was
not adopted because ``high performance'' is an undefined, subjective
term relative to airplane certification. Therefore, Sec.  23.3 is
adopted as proposed.

C. Performance, Flight Characteristics, and Other Design Considerations

1. Performance
    The FAA proposed to incorporate in part 23 the current special
conditions approach for jets weighing more than 6,000 pounds by
applying most commuter category performance requirements. The proposed
revisions to Sec.  23.45 would apply the commuter category performance
requirements for the normal, utility, and acrobatic categories to
multiengine jets weighing more than 6,000 pounds.
    As a general matter, several commenters recommended replacing

the proposed propulsion-based criteria with performance-based criteria.
The FAA agrees, as indicated in the Small Airplane Directorate's
Certification Process Study from 2009 which recommends revising part 23
based on airplane performance and complexity versus propulsion and
weight. However, amending part 23 to a performance-based standard is a
substantially larger initiative than this rulemaking effort.
    During rulemaking discussions, the ARC decided that applying the
commuter category takeoff performance requirements in proposed
revisions to Sec. Sec.  23.51 through 23.61 would include restrictions
that could become a takeoff weight limitation for operations. The
concern was that these requirements would be too restrictive for part
91 operations.
    The FAA disagreed with the ARC concerning multiengine jets weighing
more than 6,000 pounds. The FAA has several decades of experience
applying existing special conditions to part 23 jets. The performance
requirements for these jets have proven successful for part 91
operations and are necessary to maintain the existing level of safety.
    We received three comments regarding this proposal. EASA supported
the changes and suggested requirements be extended to all jets, not
just to those weighing more than 6,000 pounds. Diamond Aircraft
(Diamond) asked why this rule did not apply to turboprops and piston-
powered airplanes. Transport Canada proposed that the all-engines-
operating accelerate-stop distance be determined in addition to the
one-engine inoperative (OEI) distance, and the greater of the two be
used as the accelerate-stop distance.
    Again, the Small Airplane Directorate's Certification Process Study
from 2009 recommends revising part 23 based on performance and
complexity versus propulsion and weight. We have not yet proposed to
completely rewrite part 23, and doing so would be beyond the scope of
this rulemaking. Accordingly, no change was made to the proposal in
this final rule, except to change the word ``turbojet'' to ``jet''
wherever appropriate in this final rule.
    The FAA proposed revisions to Sec. Sec.  23.63 and 23.67 to enhance
safety by increasing the OEI climb gradient performance for multiengine
piston-powered airplanes weighing more than 6,000 pounds and for all
multiengine turbines. We proposed no change to the current 2 percent
OEI climb gradient that has been consistently applied via special
condition for multiengine jets weighing more than 6,000 pounds.
    We proposed to revise the OEI climb gradient requirements to
require a 1 percent OEI climb gradient for all multiengine turboprops
and multiengine piston-powered airplanes weighing more than 6,000
pounds. We did so because of the similarity in how these two types of
airplanes are used. Multiengine jets weighing 6,000 pounds or less will
be required to meet an OEI climb gradient of 1.2 percent with this
revision.
    The FAA has revised Sec.  23.63(c) and (d), and Sec.  23.67(b) and
(c) to reflect these changes to the climb gradient requirements. The
FAA also made a minor editorial change to replace ``turbojet engine-
powered'' with ``jet'' wherever appropriate in this final rule to
simplify the term. Table 1 summarizes those changes:

           Table 1--One-Engine Inoperative (OEI) Climb Requirements to 400 Feet Above Ground Level AGL
----------------------------------------------------------------------------------------------------------------
                                                                                ARC's         FAA's position in
           Multiengine category                     Current rule            recommendation        final rule
                                                                               (percent)           (percent)
----------------------------------------------------------------------------------------------------------------
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
Jets <= 6,000 lbs.........................  Measurably positive.........                 1.0                 1.2
Jets > 6,000 lbs..........................  2.0% imposed through special                 1.0                 2.0
                                             conditions.
----------------------------------------------------------------------------------------------------------------

    The FAA received comments on Sec. Sec.  23.63, 23.65, and 23.67
from Transport Canada, Hawker Beechcraft, and Diamond. Transport Canada
stated that the proposed Sec.  23.63 would conflict with the existing
Sec.  23.65. The FAA has accordingly revised Sec.  23.65 for
consistency. Hawker Beechcraft stated that the change from ``must be
measurably positive'' to ``may be no less than 1 percent'' could reduce
takeoff payload by a maximum of 900 pounds. This would limit the
utility of a normal category turboprop under high-hot conditions with
takeoff flaps. The FAA understands that leveling the turboprop
requirements with certain jets will cause a loss of utility and market
disadvantage. However, given similar missions (many in revenue
service), turboprops should be held to a performance standard similar
to that for jets. The FAA reviewed the current service history safety
data for these airplanes. Based on this data, the FAA only required
half the single-engine climb requirements of multiengine jets.
    Diamond stated that this makes sense to a certain degree if the
reasoning behind it is that turbines are capable of better performance
than piston-powered airplanes. However, Diamond asked if there is a
need to require compensating features if the airplane cannot meet a
reasonable climb gradient. Diamond also asked why the FAA would change
to a safer engine type if history has not shown there to be a problem
with the current engine type. Diamond further stated that this
requirement should be consistent with those for turbines, with no
distinction between jets and turboprops. The FAA partially agreed and,
as stated above, adopted an OEI climb gradient of 1 percent.
    The FAA received a comment from GE on the economic benefit of
improved climb performance. GE stated that the improved climb
performance is not a new requirement, and it is currently imposed by
special condition. Since that special condition is not changing--it is
now only being levied by this final rule--GE asked how a safety benefit
can be credited to the rule.
    The FAA believes that adding this special condition as a
requirement in part 23 will not only have a safety benefit, but it will
also enhance our efforts toward continued operational safety. Special
conditions are aircraft-specific and have not been issued for every
part 23 airplane. Section 23.67 (and Sec.  23.77, which was adopted
without change) addresses the additional climb performance for all part
23 turbojets and turboprops. The additional climb performance
requirements will apply to all new part 23 turboprops and part 23
turbojets under 6,000 pounds, thereby increasing the operational safety
of those newly certificated airplanes.
    In addition, special conditions increase paperwork and workload for
FAA and industry. Also, they create uncertainty for the manufacturer
during

design. By incorporating the improved climb performance into part 23,
special condition paperwork will be reduced and, in effect, will allow
FAA and industry resource leveraging towards other safety-critical
endeavors in our goal of continued operational safety.
    In developing cost estimates for the NPRM, the FAA contacted
members of the ARC to determine when and if special conditions were
voluntarily accepted by industry. When a special condition is
voluntarily accepted by industry, the FAA does not include the special
condition(s) cost in the regulatory impact assessment (RIA). When
industry informs the FAA that a special condition will impose costs on
industry, as do Sec. Sec.  23.67 and 23.77, the FAA estimates the
incremental cost between the current and final rule.
    The FAA proposed to correct a reference error to a velocity term in
Sec.  23.73. Maximum landing configuration stall speed (VSO)
was changed to specified flap configuration stall speed
(VS1). VSO is not applicable to other flap
configurations. The reference landing approach speed (VREF)
is based on 1.3 times the VS1. The FAA proposed to amend the
standards to address airplanes certificated under part 23 that may have
more than one landing flap setting. Additionally, the FAA proposed to
include multiengine jets weighing more than 6,000 pounds in the
commuter category requirements.
    The FAA received one comment. Diamond stated that the distinction
between jet engines and other engine types may not be appropriate. It
suggested the requirement for a higher level of safety be related to
performance, not to engine type. As stated earlier, the FAA has
determined that amending part 23 to a performance-based standard is a
substantially larger initiative and beyond the scope of this rulemaking
effort.
2. Flight Characteristics
    In Sec.  23.175(b), the FAA proposed to define the maximum speed
for stability characteristics (VFC/MFC). The term
VFC/MFC was added to part 23 in the last large-
scale revision to Subpart B, but the definition was inadvertently
omitted.
    EASA commented on multiple proposed sections that it applies a
special condition for high-speed characteristics that are not included
in our proposal. EASA's comments suggested these sections be drafted as
a performance-based standard. However, amending part 23 to a
performance-based standard is a substantially larger initiative than
this rulemaking effort.
    The FAA also received comments from Transport Canada and Cessna
regarding flight characteristics. Both commenters recommended that we
include the definition of VFC/MFC in Sec.  23.253
for consistency with part 25. The FAA agrees and has relocated the
definition for it from Sec.  23.175 to Sec.  23.253.
    The FAA proposed revisions to Sec.  23.177 that would have
clarified the specific speed limitations to include jets. The proposed
speed limitations also included specific criteria (``VFE,
VLE, VNO or VFC/MFC as
appropriate'' as defined in Part 1).
    The FAA proposed to relax the stability requirements in Sec.
23.181 for airplanes operating above 18,000. The original requirements
were developed for small airplanes typically operated under 18,000 feet
and not equipped with yaw dampers. The existing requirement is still
appropriate for low-altitude operations, such as for approaches.
However, the existing requirement is not appropriate for larger
airplanes that typically use yaw dampers and fly at altitudes above
18,000 feet. In fact, the FAA has issued multiple ELOS findings for
most certificated part 23 jets because such findings were appropriate
for high-altitude, high-speed operations.
    The FAA received comments from EASA, Cessna, and Emivest. EASA
commented in multiple sections that it applies a special condition for
high-speed characteristic not included in our proposal. EASA's comment
suggests a performance-based standard. Amending part 23 to a
performance-based standard is a substantially larger initiative than
this rulemaking effort.
    Cessna suggested Sec.  23.181 include a similar definition to the
revised Sec.  23.177. The FAA agrees with Cessna's comment and added
that definition to Sec.  23.181.
    Emivest recommended that part 23 allow the lower standard found in
part 25 for flight above 18,000 feet. The FAA disagrees with this
recommendation. Part 23 airplanes are frequently flown by a single
pilot and operated under part 91. Single pilots operating part 23
airplanes may not necessarily have the same experience level as part 25
airplane pilots. Therefore, the stability and control requirements in
part 23 will remain higher than in part 25.
    We proposed revisions to the stall requirements in Sec. Sec.
23.201 and 23.203 to include jets and a new generation of part 23
airplanes with high-power and high-altitude capability.
    The proposed revisions included:
     Incorporating additional configurations for all part 23
airplanes;
     Clarifying flap and gear position as appropriate for the
altitude and flight phase;
     Relaxing the roll-off requirements for high-altitude
stalls; and
     Defining what is meant by ``extreme nose-high attitudes.''
    The FAA received comments from the General Aviation Manufacturers
Association (GAMA) and Emivest. GAMA stated the requirement for the
demonstration of control during entry and recovery from wings level
stall is unnecessary above 1.5 VS1 instead of 1.6
VS1, as this requirement matches the requirements applicable
to part 25 airplanes. The FAA agrees and has made the necessary change
to be consistent with the requirements for part 23 jets.
    Emivest recommended the FAA allow the lower handling characteristic
standards from part 25, specifically being able to control rolling from
15 to 20 degrees of roll. The FAA does not believe that this is
appropriate for all altitudes. Parts 23 and 25 still have a
considerable number of stall/departure accidents at low altitudes, even
with stall barrier devices. The FAA is moving part 23 towards even more
benign stall characteristics and additional stall protection systems.
    The FAA determined that relieving the controllability requirements
in Sec.  23.201 across the entire altitude capability would move part
23 in the wrong direction--inconsistent with current stall
requirements. Considering that most stall accidents occur at low
altitudes, this revision would relax the stall handling characteristic
roll requirement to 25 degrees for stalls at or above 25,000 feet. We
believe this is an acceptable action for this flight regimen for the
class of airplane operating at or above 25,000 feet.
    The FAA proposed to incorporate provisions from Sec. Sec.
25.251(d) and (e) into Sec.  23.251 while limiting the requirements to
airplanes that fly over 25,000 feet or that have a Mach Dive Speed
(MD) faster than Mach (M) 0.6. The proposed revision also
included the use of VDF/MDF, as referenced in
part 23 jet special conditions.
    The FAA received similar comments from Cirrus and Transport Canada.
Cirrus stated that Sec.  23.251(b) and (c) use the term ``perceptible
buffeting,'' which is a subjective term. Cirrus requested a concise
term to differentiate ``normal vibration'' from ``perceptible
buffeting,'' or a standard definition of ``perceptible buffeting.'' The
FAA will address this comment in an advisory circular, which we believe
is the appropriate place to address it.

    Transport Canada stated that the use of operational speeds is
considered more appropriate than using a design speed as criteria. The
FAA understands the commenter's point. For this situation, however, the
FAA believes the part 23 speed rationale should parallel the rationale
in part 25 for consistency in our decisions for continued aviation
safety.
    The FAA revised Sec.  23.253(b) to add the use of demonstrated
flight diving speed (VDF/MDF) as applicable,
consistent with standards in Sec.  25.253. The FAA also moved the
proposed definition for VFC/MFC from Sec.  23.175
to this section as paragraph (d).
    The FAA proposed adding Sec.  23.255 to include new requirements
that consider potential high-speed Mach effects for airplanes with
MD greater than M 0.6. The FAA proposed these requirements,
which came from part 25, for airplanes that incorporate a trimmable
horizontal stabilizer. This decision was based on the positive service
history with the existing fleet of part 23 jets designed with
conventional horizontal tails and those that use trimmable elevators.
Airplanes that experienced upset incidents involving out-of-trim
conditions were part 25 certificated airplanes and designed with a
trimmable horizontal stabilizer.
    The FAA received a comment from Transport Canada, stating that this
requirement should apply to all horizontal tail configurations as
required for transport category airplanes. The FAA disagrees with
Transport Canada. The high-performance airplanes that will be
certificated under part 23 are similar to those that have established a
positive service history using similar regulations; therefore, this
final rule has not been changed as a result of this comment.

D. Structural Considerations for Crashworthiness and High-Altitude
Operations

1. Design and Construction
    The FAA proposed changes to Sec.  23.561 to address structural
requirements for engines contained within the fuselage and located
behind the passenger cabin. The FAA proposed these changes to: (1) Add
structural requirements to single-engine jets with centerline engines
embedded in the fuselage, and (2) minimize the likelihood of the engine
breaching the passenger compartment in the event of an emergency
landing. The proposal would have reduced the potential for the engine
to separate from its mounts under forward-acting crash loads and
subsequently intrude into the passenger compartment (i.e., cabin).
    The FAA received several comments on this proposed change. EASA
suggested the proposed rule should be expanded to include any engine
mounted inside the fuselage and aft of the cabin, not just turbojet
engines. The FAA agrees with EASA. Any engine mounted in this type of
configuration may be a hazard to cabin occupants in the event of an
emergency landing, so the regulation should not be limited to turbojet
engines. The proposed amendment has been modified to capture this
comment.
    Transport Canada stated that the proposed load factors should be
adjusted upward if the VS0 of the airplane exceeds 61 knots.
The FAA disagrees with Transport Canada since the proposed regulation
would require the engine to be retained at 18 g in combination with
maximum takeoff thrust. This approach is reasonable for engine
retention.
    Transport Canada also stated that the attached accessories need not
be required to withstand the added load of maximum engine takeoff
thrust since accessories do not react to engine thrust loads. The FAA
disagrees with this comment. While engine accessories should not
directly react to engine thrust loads, engine accessories impart a load
to their mounting structure. This load is typically highest when the
engine is producing maximum takeoff thrust. The intent of this rule is
to ensure the engine and its accessories do not penetrate the cabin in
an emergency landing.
    Transport Canada further stated that proposed Sec.
23.561(e)(1)(ii), which in the relevant part states ``to deflect the
engine'' may be too limited. The commenter suggested there are other
methods an airplane designer may propose, such as an energy-absorbing
bulkhead or barrier. We agree, and by adopting this comment, the rule
will be more performance-based and preclude dictation of the airframe
design. The FAA has changed this final rule accordingly.
    The FAA proposed changes to Sec.  23.562 to require dynamic seat
testing for commuter category jets. The FAA also proposed changes to
the Head Injury Criteria (HIC) calculation in Sec.  23.562 to be
consistent with the HIC calculation contained in Sec.  25.562.
    Our intent with the proposed rule was to codify a requirement that
has become industry practice. All manufacturers of those recently
certificated commuter category jets have agreed to comply with Sec.
23.562. It was not our intent to include commuter category propeller-
driven airplanes in Sec.  23.562 in light of the rulemaking history
associated with that effort.\1\ The FAA has decided against adding
commuter category propeller-driven airplanes to Sec.  23.562 at this
time. The FAA reserves the right, however, to reconsider this position
in the future should adverse service history suggest changes are
necessary.
---------------------------------------------------------------------------

    \1\ The FAA provided a history of the previous rulemaking effort
in the NPRM. 74 FR 41522.
---------------------------------------------------------------------------

    In addition, the FAA received comments from several organizations
indicating a mistake in the proposed HIC calculation. The commenters
stated that the proposed definition of ``a(t)'' would require
calculating HIC for the entire head acceleration time, not just for the
time of impact with interior components. The FAA agrees the proposed
rule did not specify the word ``strike'' when defining ``a(t)'' as the
total acceleration versus the time curve for a head strike. The FAA has
made the necessary changes to the definition of ``a(t)'' in this final
rule so it is clear that HIC is calculated for the head strike only.
    The NPRM included new sections in Sec. Sec.  23.571, 23.573, and
23.574, which noted additional requirements referencing the new high
altitude requirements of Sec.  23.841(e). These additional requirements
included the establishment of a Limit of Validity (LOV), as well as
additional test requirements. Several commenters, including Cessna and
GAMA, objected to the LOV concept due to the burden it could place on
applicants. Upon consideration of these comments the FAA agrees we need
additional time to consider the need for LOV. Therefore, we
consolidated the requirements into Sec.  23.571(d) and removed the
reference to Sec.  23.841. Proposed Sec.  23.841(e), which contained
the LOV and additional test requirements, has been withdrawn.
    Section 23.571(d) still requires the damage tolerance option under
Sec.  23.573 to be used on airplanes that exceed 41,000 feet. Section
23.571(d) will also require that damage tolerance be used to evaluate
structure for operations above 41,000 feet on all airplanes except
commuter category. Commuter category airplanes are already required to
use damage tolerance under Sec.  23.574. The FAA has modified Sec.
23.571 as discussed and withdrawn the proposed revisions to Sec. Sec.
23.573 and 23.574.
    In addition, GE stated it would be difficult to comply with the
proposed Sec.  23.841, given all of the exemptions granted for this
rule in the past. The FAA disagrees with this comment, but GE is
correct that a number of exemptions have been granted.

However, all but one of the exemptions were for part 25 airplanes. This
single part 23 airplane exemption dealt with the method of compliance
for this rule. (See Exemption No. 5223; also, a copy of this exemption
will be placed in the docket for this rulemaking.)
    As noted above, the proposed rule has been revised, and previous
part 25 exemptions are irrelevant to the subject part 23 airplanes.
Several jets have successfully met depressurization profiles, thereby
meeting appropriate part 23 certification requirements.
    The FAA proposed to clarify the use of either the MD or
the Dive Velocity (VD) in Sec.  23.629, whichever is
appropriate, for jets. As dive speeds increase with high performance
airplanes, the compressibility effects of the air become more
significant; therefore, it is more appropriate to refer to
MD instead of VD. Proposed changes would have
also allowed the use of a ``demonstrated'' flight dive speed
(VDF/MDF) instead of the theoretical speeds
(VD/MD) when flight flutter testing jets. Using a
demonstrated speed, in lieu of a theoretical speed, can relieve some
compliance burden when an airplane is unable to attain those
theoretical dive speeds during the test phase of an airplane
certification program.
    Cessna stated that the FAA was attempting to align the part 23
small airplane flutter requirements with those of part 25 for transport
category airplanes. The FAA does not agree with this summary of the
change. While the change is similar to certain transport category
requirements, there was no decision in this case to make this part 23
requirement identical to part 25 requirements. The FAA seeks only to
establish a category-appropriate rule for jets which balances many
factors; those factors include risk management, safety, and cost.
    Cessna stated that in one paragraph the FAA only made the change to
add the Mach dive speed designation, but did not include the option for
the demonstrated flight speeds. The FAA agrees with Cessna. It was
inadvertently omitted from the proposed rule language. The FAA adopted
that change in the final rule.
    Cessna further stated the proposal implied that the flutter
analysis need only be performed to the demonstrated flight speed. The
FAA agrees the wording was misleading and ambiguous. Therefore, the
proposed language is revised to clarify that the flutter analysis must
be performed to 20 percent above the design dive speed or 20 percent
above the design Mach dive speed, whichever is appropriate.
Additionally, Sec.  23.629 is revised to clarify that the 20 percent
margin above the design dive speed need not go above Mach 1.0, as this
unnecessarily complicates the analysis.
2. Other Design Considerations
    Proposed revisions to Sec.  23.703 introductory text and paragraph
(b) would have added takeoff warning system requirements to all
airplanes weighing more than 6,000 pounds and to all jets. 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.
    The FAA received two comments. EASA suggested the rule did not
address all devices for a safe takeoff. Diamond asked why this rule did
not apply to turboprops and piston-powered airplanes.
    Parking brakes and antiskid devices are optional installations and
cannot be required by this rule; but if installed, optional
installations can be included in the determination of an unsafe takeoff
condition. Also, this rule applies to all airplanes weighing more than
6,000 pounds and to jets of any weight. Therefore, turboprops and
piston-powered airplanes weighing more than 6,000 pounds are included.
The FAA inadvertently modified Sec.  23.703(b) in the NPRM. Our intent
was to add a new section, Sec.  23.703(c). The FAA is adopting Sec.
23.703(c) as originally intended and with a minor editorial change.
    The FAA changed the rejected takeoff requirements in Sec.  23.735,
which were previously only for commuter category airplanes, to be
applicable for all multiengine jets weighing more than 6,000 pounds.
The higher takeoff speeds and distances for these airplanes make the
ability to stop in a specified distance a safety issue.
    Two commenters suggested adding similar rejected requirements from
part 25. Adding these part 25 requirements, however, was not part of
the NPRM. In this case, the part 25 requirements are too stringent for
part 23 airplanes. We cannot justify those more stringent requirements
based on our current service history.

E. Powerplant and Operational Considerations

    Previous amendments to Sec.  23.777 standardized the height and
location of powerplant controls because pilots may become confused and
use the wrong controls on propeller-driven airplanes. However, previous
amendments did not include single-power levers (which are typical for
electronically-controlled engines). The FAA made an ELOS finding for
each airplane program that included a single-power lever. Revised
paragraph (d) in Sec.  23.777 incorporates the ELOS language.
    The FAA received one comment that the requirement for power
(thrust) levers should be easily distinguishable for human factor
considerations instead of one inch higher than mixture and propeller
levers. The FAA agrees with this comment and revised the rule to delete
the one-inch requirement and changed the wording to easily distinguish
the power levers from other controls.
    The FAA proposed to provide an alternative to meeting the
requirement for an emergency exit above the waterline on both sides of
the cabin for multiengine airplanes. The proposed change to Sec.
23.807 allows the placement of a water barrier in the main cabin
doorway before the door is opened as a means to comply with the above
waterline exit requirement. This barrier is above the waterline and
slows the water inflow, thus allowing exit through the main cabin door
in a ditched airplane. The FAA approved the use of this barrier as an
alternative to the above waterline exit for several airplanes by
issuing an ELOS finding.
    The FAA received two comments. Emivest stated the rule language
would permit a main cabin door below the waterline to be approved as an
emergency exit. Embraer stated a water barrier should be allowed
regardless of whether the main cabin door is above the waterline since
the determination of the waterline is undefined.
    The FAA disagrees with both comments. The new Sec.  23.807(e)(3)
states ``may'' because the new paragraph is an option for paragraph
(e)(2), which specifies an overhead exit if side exits cannot be above
the waterline. Furthermore, buoyancy analysis is standard practice to
determine the waterline of an airplane. There is no reason to provide a
water barrier if the emergency exit is above the waterline. Therefore,
no changes were made to the proposal in this final rule.
    The FAA proposed amending Sec.  23.831 by adding new paragraphs (c)
and (d), which would include standards appropriate for airplanes
operating at high altitudes beyond those included in part 23. The
changes were intended to ensure that flight deck and cabin environments
do not result in the crew's mental errors or physical exhaustion. Such
an event would prevent the crew from successfully completing assigned
tasks for continued safe flight and landing of an airplane. An
applicant

may demonstrate compliance with paragraph (d) of this requirement if
the applicant can show the flight deck crew's performance is not
degraded.
    Several new part 23 jet certification programs include approval for
operations at altitudes above 41,000 feet. Additionally, the FAA issued
special conditions for operations up to 49,000 feet and changed rules
for structures and the cabin environment to ensure structural integrity
of the airplane at higher altitudes. The FAA also made 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.
    The FAA intended the requirement ``* * * must not affect crew
performance so as to result in a hazardous condition * * *'' to mean
the crew can reliably perform published and trained duties to complete
a safe flight and landing. In the past, a person's ability to track and
perform tasks was measured by crew performance; however, acceptable
crew performance is limited to the procedures defined by the
manufacturer or required by existing regulations. The FAA uses ``No
occupant shall sustain permanent physiological harm'' to describe the
requirement that occupants who may have required some form of
assistance must be expected to return to their normal activities once
treated.
    Cirrus and Transport Canada stated the proposal, as written,
applied to all phases of flight, including slow speed phases. The
proposal was intended to apply to flight above 41,000 feet. The final
rule for paragraphs (c) and (d) is changed to state the paragraphs are
applicable only for the cruise phase of flight above 41,000 feet.
    Diamond suggested the rule should apply to all pressurized
airplanes, not just to jets. The intent of the proposal was for it to
apply to airplanes that operate above 41,000 feet. The FAA is unaware
of any turboprops or piston-powered airplanes that operate above 41,000
feet. Special conditions would be applied to a turboprop or piston-
powered airplane with a maximum service ceiling above 41,000 feet.
    EASA stated two figures used for high-altitude airplanes, regarding
the time temperature correlation, were not included. That oversight is
corrected in this final rule.
    We proposed amending requirements 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 changes provide
airworthiness standards that allow subsonic, pressurized jets 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 are protected from the effects of hypoxia (i.e.,
deprivation of adequate oxygen supply), and (3) if some occupants do
not receive supplemental oxygen, they are protected against permanent
physiological harm.
    Several new part 23 jet certification programs include approval for
operations at altitudes above 41,000 feet. Additionally, we issued
special conditions for operations up to 49,000 feet. In this final
rule, we changed rules for structures and the cabin environment to
ensure structural integrity of the airplane at higher altitudes.
    Earlier amendments required the cabin pressure control system to
maintain the cabin at an altitude of not more than 15,000 feet if any
probable failure or malfunction in the pressurization system occurred.
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. The FAA granted ELOS
findings for this characteristic because physiological data show that
the brief duration of the overshoot has no significant effect on an
airplane's occupants.
    Special conditions issued for part 23 jets to operate at altitudes
above 41,000 feet are equivalent to the requirements in Sec.  25.841
adopted in Amendment 25-87 (61 FR 28684, June 5, 1996). The amendment
in this final rule modified Sec.  23.841 to include requirements for
pressurized cabins previously covered only in special conditions. The
special conditions required consideration of specific failures. Part 25
incorporated reliability, probability, and damage tolerance concepts
addressing other failures and methods of analysis after the issuance of
the special conditions. Sections 23.571, 23.573, and 23.574 address the
damage tolerance requirements. This final rule requires the use of
these additional methods of analysis.
    Part 23 requires a warning of an excessive cabin altitude at 10,000
feet. Part 23 does not adequately address operations at airfield
elevations above 10,000 feet. Rather than disable the cabin altitude
warning to prevent nuisance warnings, the FAA has issued ELOS findings
allowing the warning altitude setting to be shifted above the maximum
approved field elevation, not to exceed 15,000 feet. The FAA proposed
to modify Sec.  23.841 to incorporate language from existing ELOS
findings into the regulation.
    The FAA received nine comments on this proposal. Several commenters
disagreed with the structure of the initial proposed rule, the use of
the noted damage tolerance principles, and the general systems rule for
pressurization at high altitude. While EASA supported establishment of
a Limit of Validity (LOV) and additional testing, Cessna, Embraer, and
GAMA disagreed with the implementation of these concepts, which are not
currently used in part 23.
    In response to comments from GAMA and Embraer, the FAA changed
paragraph (b)(6)(ii) to permit a single operation for high altitude
takeoffs and landings. In response to a comment from GE, paragraph
(c)(2) is changed to exclude improbable failures.
    In addition, ruptures must be limited to control pressurized cabin
breeches. Rapid pressure loss at high altitudes may result in
physiological damage to the occupants. Section 23.841 defines
acceptable depressurization profiles in such an event, and the
pressurized structure serves as a part of the system to ensure the
minimum cabin pressure is maintained. To control the cabin pressure
vessel breeches in the fuselage structure, the noted damage tolerance
principles are used (specifically borrowing the process referenced in
Sec.  23.573(a) or (b)).

F. General Fire Protection and Flammability Standards for Insulation
Materials

    The FAA proposed upgrading flammability standards for thermal and
acoustic insulation materials by adding a new Sec.  23.856. The
previous standards did not realistically address situations where
thermal or acoustic insulation materials may contribute to producing a
fire. The changes are based on the requirements in Sec.  25.856(a) and
part VI, Appendix F, which were adopted following accidents involving
part 25 airplanes, such as the Swissair MD-11. The proposed new
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 new standards also would include flammability tests
and criteria that address flame propagation. They would apply to
thermal/acoustic insulation material installed in the fuselage of part
23 airplanes.
    Prior amendments focus almost exclusively on materials located in
occupied compartments (Sec.  23.853) and cargo and baggage 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 or
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
and is 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, April 2000.
    Cessna stated this proposal should be limited to commuter category
airplanes. The FAA disagrees because this hazard is not limited to
commuter category airplanes. In addition, there has been a
certification project to install this insulation in a normal category
airplane.

G. Additional Powerplant and Operational Considerations

    We inadvertently proposed to add requirements to Sec.  23.903(b)(2)
when we meant to propose a new paragraph (b)(3). This proposal was
intended to protect passengers and maintain the ability for continued
safe flight and landing following a fan disconnect event for fuselage-
embedded, jet-engine installations.
    The FAA received six comments on this proposed rule change. Cirrus
favors avoiding the use of the ``embedded'' classification altogether;
the FAA does not. The crux of Cirrus' position relates to the
requirements for fire protection of embedded engines, and not
protection against fan disconnect. Hawker Beechcraft, GE, and EASA
commented on assessing the threat from fan disconnect questions as the
means of compliance to this rule change.
    For each airplane with an embedded engine, the FAA will provide
project-specific guidance for an acceptable means of compliance
regarding fan-disconnect concerns. If the engine does not have a
failure mode that results in a fan-disconnect event, then basic
compliance would need to show the failure cannot occur. In this
instance, no further showing of compliance would be required. Transport
Canada supports the rule change.
    The FAA proposed adding a paragraph to Sec.  23.1141 to require
electronic engine control systems to meet the equipment, systems, and
installation standards of Sec.  23.1309. The FAA has applied this
requirement to all digital engine control installations in part 23
airplanes by special condition for over ten years. The proposed rule
change for Sec.  23.1141 would have codified the requirements
previously applied via special condition.
    The FAA received six comments on this proposed rule change. Most of
the comments questioned the need for the specific application of Sec.
23.1309 to electronic engine control systems. Diamond, GAMA, and Hawker
Beechcraft stated that compliance was already required. Cessna stated
there were similar requirements in Sec.  23.1141(e). GE stated there
were no commensurate requirements in part 25, and that engine control
was certificated in part 33. Transport Canada suggested the change
should only address the electromagnetic environment and compatibility
requirements, rather than all of Sec.  23.1309.
    The FAA has not directly adopted these comments. However, the
comments highlighted the difficulties in using Sec.  23.1309 as the
primary means by which to certificate electronic engine control system
installation. There are conflicts between the guidance material for
Sec.  23.1309 and propulsion system certification. One example is a
single-engine turbine-powered airplane with a failure of the electronic
engine control system which cannot meet the failure probability
commensurate with the hazard. As a result, applicants have elected to
declare a reduced hazard severity of a failure of the electronic engine
control system. This is not the intent of Sec.  23.1309. The greater
hazard severity should drive lower probability of failure, and the
higher probability of failure should not drive the lower hazard
severity.
    There is also a conflict between the hazard severity of a failure
of an electronic engine control system and the required test levels for
lightning and high intensity radiated frequency (HIRF). Testing to a
level lower than required for a catastrophic failure results in a lower
level of safety than the mechanical system it replaces. This is
contrary to the intent of the certification requirements. As a result,
the FAA decided to withdraw the proposed rule change and will continue
to require the test levels via special conditions.
    We also proposed to expand the requirement in Sec.  23.1165(f) for
all turbine engine installations in commuter category airplanes, as it
is currently limited to turboprops. The revision to the rule covers all
turbines in the commuter category and removes the propeller driven
restriction. (The definition of commuter category is also changed in
Sec.  23.3(d).)
    Transport Canada stated that the proposed rule conflicted with the
gas turbine ignition systems for restarting an engine in flight, as
required by Sec.  23.903(e)(3), (f) and (g). The FAA does not agree
with this comment, as there is no conflict with the cited rules.
Embraer suggested that the rule should be reworded to state ``* * *
each turbine engine ignition system must be considered an essential
electrical load.'' The FAA disagrees, as the suggested change does not
change the substance of the rule. The proposal is adopted without
change.

H. Additional Powerplant Fire Protection and Flammability Standards

    When the FAA initially introduced powerplant fire protection
provisions in part 23, jet engines were not embedded in the fuselage,
or in pylons on the aft fuselage, for airplanes certificated to part 23
standards. Sections 23.1193, 23.1195, 23.1197, 23.1199, and 23.1201
added fire protection requirements for commuter category airplanes.
    Manufacturers also provide fire prevention through minimizing the
potential for the ignition of flammable fluids and vapors.
Historically, pilots were able to see engines and identify fires or use
the incorporated fire detection systems, or both. The ability to see
engines provided for the rapid detection of fires, which led to fires
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.
    For airplanes equipped with fuselage-embedded engines, the
consequences of a fire are more varied, adverse, and difficult to
predict than an engine fire for a typical part 23 airplane. An engine
embedded in the fuselage offers minimal opportunity to actually see a
fire. Therefore, an engine's location becomes critical to the ability
to see and extinguish an engine fire. With fuselage-embedded engines,
an engine fire could affect both the airplane's fuselage and the
empennage structure, which include the pitch and yaw controls. A
sustained fire could further result in the loss of airplane control
before a pilot could make an emergency landing.

    Transport Canada stated that a clarification for embedded engines
would be useful. The FAA believes the term ``embedded'' is not
confusing. A general definition of the term, which is to enclose
closely in a surrounding mass, is adequate. Therefore, we do not
provide further clarification of the term in this final rule.
    The FAA also proposed to change requirements in Sec.  23.1195 for
fire extinguishing systems, extinguishing agent containers, and fire
extinguishing system materials. Diamond and Cirrus stated the issue is
location of the engine(s) rather than the airplane category or type of
engine. The FAA agrees and modified the rule to make it applicable to
all part 23 airplanes with fuselage-embedded engines and to any part 23
airplanes with engines mounted in pylons on the aft fuselage. For
embedded engine installations, a two-shot fire-extinguishing system
would be required because the metallic components in the fire zone can
become hot enough to reignite flammable fumes after extinguishing the
first fire.
    GAMA, Cessna, and Cirrus objected to the requirement for a two-shot
fire extinguishing system if an engine is embedded. Commenters had
various reasons for their objections. However, while engines other than
those embedded in a fuselage could reignite a fire, the hazard of fire
damage to empennage flight controls or primary structure is greater for
embedded engines than for other engine mounting installations. Cirrus
also stated the rule change was not needed because small airplanes,
including some jets, can descend and land in 15 minutes, as stated in
the NPRM.
    We agree that some jets will likely be able to descend and land in
15 minutes without a problem, if an adequate airport is available.
However, altitude is only one issue. These airplanes are approved for
Instrument Flight Rules (IFR), so the ability to continue safe flight
and landing also must consider time to descend under Air Traffic
Control (ATC) through Instrument Meteorological Conditions (IMC) and
make an approach and a go-around. Also, the ability to land off airport
is an issue for an airplane with a 65 knot or higher stall speed.

I. Avionics, Systems, and Equipment Changes

    The FAA proposed removing Sec.  23.1301(d) to improve
standardization for systems and equipment certification, particularly
for non-required equipment and non-essential functions embedded within
complex avionic systems. EASA stated it will retain Sec.  23.1301(d).
Individuals also asked the FAA to retain this paragraph for non-
required equipment and systems and intended functions.
    Section 23.1301(d) is directed towards environmental qualifications
and operating conditions of the equipment and systems. The requirement
in Sec.  23.1309(a) replaces the requirement in Sec.  23.1301(d) and,
if Sec.  23.1301(d) were retained, there would be a duplication of
requirements. The requirement for intended function is further
explained in Sec. Sec.  23.1309(a)(1) and (a)(2) and the NPRM.
    Removal of Sec.  23.1301(d) aligns with the proposed changes to
Sec.  25.1301(d) that was developed by the Joint Aviation Authorities
(JAA) of Europe and the Aviation Rulemaking Advisory Committee (ARAC),
which was established on January 22, 1991 (56 FR 2190). We have decided
to adopt this proposal without change.
    Proposed Sec.  23.1305 would have eliminated the need for an ELOS
finding for digital engine display parameters. It would have added
requirements regarding usability for an ELOS finding. In addition, the
ELOS finding would include the requirements for color indications for
normal operation, operation in a caution range, and exceeding any
limitation. These changes, however, were not part of the NPRM.
Furthermore, there would still be a need for an ELOS finding for
digital engine display parameters due to the digital indications being
noncompliant with the requirements of Sec.  23.1549.
    The FAA received seven comments. The FAA did not adopt these
comments since the FAA is withdrawing the proposed change to Sec.
23.1305.
    The FAA proposed Sec.  23.1307 to require applicants to install the
equipment necessary for anticipated operations (for example, operations
identified in parts 91 and 135 and meteorological conditions). Cirrus,
Embraer, and GAMA stated that the examples identified in proposed Sec.
23.1307 add little value and could increase burden on the manufacturer.
The FAA agrees the certification applicant does not need to comply with
the operational requirements of parts 91 and 135 at the time of
certification. Therefore, we are withdrawing this proposal.
    The FAA proposed changing the requirements for two different types
of equipment and systems installed in the airplane. Section 23.1309
lists the qualifiers ``under the airplane operating and environmental
conditions.'' This section also describes two actions for the
applicant. First, the applicant must consider the full normal operating
envelope of the airplane, as defined by the Airplane Flight Manual,
with any modification to that envelope associated with abnormal or
emergency procedures and any anticipated crew 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.''
    Section 23.1309(a)(2) requires analysis of any installed equipment
or system with potential failure condition that are catastrophic,
hazardous, major, or minor to determine their impact on the safe
operation of the airplane. The applicant must show that they do not
adversely affect proper functioning of the equipment, systems, or
installations covered by Sec.  23.1309 and do not otherwise adversely
influence the safety of the aircraft or its occupants.
    Section 23.1309(a)(2) does not mandate that non-required equipment
and systems function properly during all airplane operations once in
service, provided all potential failure conditions have no effect on
the safe operation of the airplane. The equipment or system must
function in the manner expected by the manufacturer's operating manual
for the equipment or system. An applicant's statement of intended
function must be sufficiently specific and detailed so that the FAA can
evaluate whether the system is appropriate for the intended
function(s).
    Garmin and Hawker Beechcraft stated, ``* * * radio frequency energy
and the effects (both direct and indirect) of lightning strikes''
should be removed from Sec.  23.1309(a)(1). Their rationale is that
there are specific requirements in Sec.  23.1308 for HIRF and for
lightning in Sec. Sec.  23.867 and 23.954.
    The NPRM included this phrase to replace the existing general
requirements in Sec.  23.1309(e) for the indirect effects of lightning.
Since there is a specific HIRF requirement in Sec.  23.1308, the FAA
agrees to remove the words ``radio frequency.'' Sections 23.867 and
23.954 are requirements for the direct effects of lightning; therefore,
the FAA also agrees to remove the word ``direct.''
    Several months after the FAA issued the NPRM for this rule, the FAA
issued an NPRM (75 FR 16676, April 2, 2010) proposing specific
requirements for the indirect effects of lightning in proposed Sec.
23.1306. The FAA plans to keep the requirement for indirect effects of
lightning in Sec.  23.1309(a)(1) until that final rule publishes.
    GAMA and Garmin suggested deleting the phrase ``or systems whose
improper function could reduce safety'' in

Sec.  23.1309(a)(1). However, they agree to the explanation of the
requirements in the preamble of the NPRM. They also stated the rule
would be challenging to comply with since proposed Sec.  23.1309(b)
deals with failure conditions such as the effects of malfunctions. The
FAA agrees and has removed the phrase.
    Several commenters stated that Sec.  23.1309(a)(2) should be
revised by replacing the beginning phrase ``Those required for type
certification or by operating rules and other'' with ``Any.'' This
revision is not a substantive change, and the FAA has revised the
phrase as requested.
    Cessna and Garmin stated that the safety assessment process in
proposed Sec.  23.1309(b) should not supersede the HIRF requirements of
Sec.  23.1308 and proposed Sec.  23.1306, electrical and electronic
system lightning protection. They also stated that the environmental
effects, such as HIRF and lightning, should not be considered in
combination with another single failure or pre-existing latent failure.
The FAA agrees.
    We proposed that Sec.  23.1309(a)(3) be applicable for all
functional reliability, flight testing, or flight evaluations. Proposed
Sec.  23.1309(a)(3) was revised to be applicable during Type Inspection
Authorization (TIA) and FAA flight-certification testing.
    Proposed Sec.  23.1309(a)(3) is being changed to Sec.  23.1309(b)
in this final rule. Cessna, Embraer, and Garmin stated that the
probability requirements were not appropriate for typical certification
flight test, but portions of the preamble material are appropriate for
advisory material. They also commented that root cause analysis and
corrective action is the current industry practice and should be
reflected in the rule. The FAA does not intend for the probability
requirements, based on random distribution across a fleet of aircraft,
to be applied on the beginning phase of operation. The FAA accepted
these comments and modified proposed Sec.  23.1309(b) in this final
rule. This section was revised to be applicable during TIA and FAA
flight-certification testing. This requirement now reads: ``Minor,
major, hazardous, or catastrophic failure condition(s), which occur
during TIA or FAA flight-certification testing, must have root cause
analysis and corrective action.''
    The FAA expects the applicant to show the system does not exhibit
unintended or undesirable failure conditions that are minor, major,
hazardous, or catastrophic. Guidance will be provided in AC 23.1309-1E.
    Garmin stated that the FAA removed the catastrophic failure
condition limitation for the Visual Flight Rules (VFR) airplane from
proposed Sec.  23.1309(b) without explanation. We removed this
limitation since airplanes limited to VFR operation may have
technologies that were not envisioned when Amendment 23-41 was
developed. The advanced complex technologies now being installed also
need to undergo the system safety assessment process.
    Several proposed amendments to introductory text for Sec.  23.1309
and Appendix K would have codified a long-established means of
compliance with current equipment, systems, and installations
requirements. We also proposed updating 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)). Some of this material identifies four
classes of airplanes, as defined in Appendix K, and applies appropriate
probability values and development assurance levels for each class. The
FAA added this material as proposed requirements in the NPRM due to
problems with one significant certification program.
    EASA stated that the proposed requirements and current requirements
are applicable and no hierarchy is implied. EASA also stated that both
specific and general requirements should apply, and the exceptions to
other requirements should be listed. Time and the often case-by-case
nature of exceptions do not permit the FAA to list all (potential)
exceptions for Sec.  23.1309. The FAA has withdrawn the proposed
exceptions from Sec.  23.1309 but will list some of them in AC 23.1309-
1E. The FAA will determine and consider additional exceptions in future
revisions of AC 23.1309. Until then, applicants and certification
authorities should contact the FAA, Small Airplane Directorate for
approval of additional exceptions.
    Boeing, Cessna, Cirrus, Diamond, Embraer, GAMA, Garmin, GE, and
Hawker Beechcraft stated that the guidance and clarification to
proposed sections and Appendix K should not be regulatory text and
should only be in the guidance material of AC 23.1309-1E. They stated
that most of these proposed changes would result in more confusion and
less standardization. They also asserted that there would be more
exemptions, ELOS findings, and complicated compliance demonstrations
with no safety benefit. As such, this would cause additional burden,
inefficiencies, and cost. The commenters further asserted that having
this material available only as guidance would allow the applicant to
choose an alternative to the proposed requirements as a means of
compliance.
    The FAA acknowledges that there has not been a problem with most
applicants using this material as a means of compliance when only using
AC 23.1309-1D, except for one type-certification program. Therefore,
the FAA has decided not to proceed with the pertinent proposed
amendments to Sec.  23.1309(b)(4), (b)(5), (c), (d), and (e) and will
also not codify Appendix K. As requested, this material will remain
available as a means of compliance in AC 23.1309-1E. Proposed
Sec. Sec.  23.1309 (b)(1), (b)(2), and (b)(3) are now redesignated as
Sec. Sec.  23.1309(c)(1), (c)(2), and (c)(3) since proposed Sec.
23.1309(a)(3) is redesignated as Sec.  23.1309(b) in this final rule,
as discussed above.
    Cirrus stated that note 5 in figure 2 of AC 23.1309-1C/D, should
also be in Appendix K. Neither Appendix K nor figure 2 of AC 23.1309-1E
contained note 5 as AC 23.1309-1C/D did. Note 5 allows an additional
reduction of Development Assurance Level (DAL) for Navigation,
Communication, and Surveillance Systems if an altitude encoding
altimeter transponder is installed and it provides the appropriate
mitigations.
    This note was deleted since it was misused, and it is not
appropriate to use a transponder as mitigation. If the transponder is
actually providing mitigations for failure conditions, then the note is
unnecessary for the system assessment process. Note 5 is removed from
AC 23.1309-1E and, as stated above, the proposal to codify Appendix K
is withdrawn.
    GE stated that the implementation of the four classes of airplanes,
in Appendix K of the NPRM, has a sliding scale of acceptable risk/
severity. That scale depends on airplane category, and it introduces
inconsistency with other rules. GE believes this may lead to confusion
of different numeric interpretations depending on the size of the
airplane.
    The FAA developed the four classes of airplanes in AC 23.1309-1C
over 10 years ago for the implementation of modern avionics that
provide safety benefits in part 23 airplanes. History has shown that
developing the four classes improves safety, without confusion, due to
the new features on electronic systems being installed. The aviation
industry as a whole is on the threshold of a revolutionary change in
communication, navigation, and surveillance of aircraft operations. The
four-class certification criteria have

been shown to be beneficial for new technologies and affordable for
General Aviation. The FAA considers the four-classes more appropriate
for an advisory circular and has decided to retain the four classes of
airplanes in AC 23.1309-1E and to remove Appendix K.
    The FAA proposed revising Sec.  23.1309(f) to make it compatible
with the current Sec.  23.1322 (``Warning, caution, and advisory
lights''), which distinguishes between caution, warning, and advisory
lights installed on the flight deck. Other paragraphs were deleted from
this section, as mentioned earlier; therefore, Sec.  23.1309(f) has
been redesignated as Sec.  23.1309(d). Rather than only providing a
warning to the flight crew, which is required by the current rule,
newly redesignated Sec.  23.1309(d) requires that information
concerning an unsafe system operating condition(s) be provided to the
flight crew.
    Section 23.1309(d) also specifies 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 include those caused by inappropriate actions by a crewmember
in response to the failure, or those that could occur after a failure.
    The FAA proposed a new Sec.  23.1310 that was previously part of
Sec.  23.1309. The proposed change would not have changed the current
requirements; the only change would have been the new section
designation.
    In the past, Sec.  23.1309 and Sec.  25.1309 had the same power
source requirements. Then, there was a proposal for part 25 to move
these requirements from Sec.  25.1309 to Sec.  25.1310 without change.
In Amendment 25-123 (72 FR 63405, November 8, 2007), the proposed
requirements were changed for clarification without substantial changes
to the requirements.
    GAMA suggested a revision for clarification. Therefore, the FAA
made a change to Sec.  23.1310 in the final rule by adopting the
requirements in Sec.  25.1310. This will also provide consistency in
our standards.
    The FAA also proposed amendments for plain language purposes.
Transport Canada stated the word ``instrument,'' which appears in
several section titles in part 23, should be replaced with
``indications.'' The FAA disagrees and maintains that the use of the
word ``instrument'' is clear and appropriate.
    GAMA stated the requirements in Sec.  23.1311(a)(5) should only be
applicable when part 23 airplanes are operating in IFR conditions. GAMA
also noted that some of the equipment listed, like attitude, is not
required for Visual Flight Rules (VFR). The FAA agrees attitude
instruments are not required for VFR operations under part 91.
    The redundancy requirements for some flight instruments or
indicators may be too restrictive for airplanes limited to VFR
operations only. This has caused several applicants to request an ELOS
from Sec.  23.1311(a)(5) for installation approval of electronic
displays in part 23 airplanes limited to VFR operations only. The FAA
agrees with this comment since it would reduce the burden of processing
multiple ELOS findings.
    We proposed clarifying the requirements for ``sensory cues'' in
Sec.  23.1311(a)(6). We also proposed amending Sec.  23.1311(a)(7) to
make acceptable instrument markings on electronic displays equivalent
to those instrument markings on conventional mechanical and
electromechanical instruments. Several commenters suggested minor
changes to the requirements for clarification. The FAA agrees with most
of these changes and has made them in this final rule.
    The FAA proposed amending Sec.  23.1311(b) by replacing the phrase
``remain available to the crew, without need for immediate action''
with ``be available within one second to the crew by a single pilot
action or by automatic means.'' This proposal would allow an applicant
to take credit for reversionary or secondary flight displays on multi-
function flight displays that provide a secondary means of primary
flight information.
    Embraer stated the one-second requirement in Sec.  23.1311(b)
should be limited to the display of attitude. The FAA disagrees but
acknowledges that in most current certifications of part 23 airplanes,
the attitude is the only information considered essential for continued
safe flight and landing. The FAA does not want to limit the one-second
requirement to only attitude. With the expansion of future advanced
technologies, some airplanes may have other information essential for
continued safe flight and landing.
    GAMA, Cessna, and Garmin commented on making minor changes to
proposed Sec.  23.1311 for clarification. We incorporated most of these
changes. Garmin suggested other minor recommendations to the NPRM. We
also accepted most of these recommendations. They will be reflected in
AC 23.1311-1C.
    To meet the jet performance requirements in Subpart B, the pilot
needs accurate speed indicators while accelerating on the runway. We
proposed revisions to add the requirement to calibrate the airspeed
system down to 0.8 of the minimum value of V1. We also
proposed the language used in part 25 for this same requirement because
it is more in line with operating new part 23 jets.
    Diamond asked why this requirement is specific to jets and commuter
category aircraft. Additionally, Diamond found the wording used in
proposed Sec.  23.1323(e) confusing and suggested that it be reworded.
If the intent is to keep this rule applicable to multiengine and
commuter jets, then the commenter recommends removing the words normal,
utility, and acrobatic (which represent the different categories of
aircraft).
    The requirement in the prior amendment for Sec.  23.1323(e) was
applicable to the commuter category because only those part 23
airplanes were required to be certificated for accelerate-stop testing.
The proposed amendment changed Sec.  23.55 to require accelerate-stop
testing for multiengine jets weighing more than 6,000 pounds, as well
as commuter category airplanes. A multiengine airplane can be commuter
category, but it may also be in the normal, utility, or the acrobatic
category. This final rule will clarify that all multiengine jets
weighing more than 6,000 pounds are subject to accelerate-stop testing,
regardless of category or whether it is a turboprop or jet. This final
rule also adds the requirement to calibrate the airspeed system down to
0.8 of the minimum value of V1.
    Changes to pitot heat indication systems requirements in Sec.
23.1326 were not included in the NPRM. Cessna stated that the previous
rule required an amber light during startup and taxi when there was no
safety issue. Since current annunciation systems provide the ability to
change the annunciation of pitot heat during flight phases to amber,
the rule should acknowledge the capability. Cessna suggested that the
rule specify the following: ``If a flight instrument pitot heating
system is installed to meet the requirements specified in Sec.
23.1323(d), an indication system must be provided to indicate to the
flight crew when that pitot heating system is not operating during
takeoff or in flight.''
    The FAA agrees, but the amber light must be operating except when
the airplane is on the ground. However, since this comment is beyond
the scope of the current rulemaking, the FAA did not include this
change in the final rule.
    The FAA further proposed to change requirements for instruments
that use a power source. Proposed Sec.  23.1331 would apply to
instruments that rely on

a power source to provide required flight information for IFR
operations. Independent power sources must be provided for these
instruments or a separate display of the parameters that have a power
source independent from the airplane's primary electrical power system.
Embraer requested clarification of Sec.  23.1331(c)(2) without
substantial change to the requirements. The FAA agrees and made those
changes in this final rule.
    Cirrus stated that an additional heading display should not be
required in Sec.  23.1331(c)(2) for small general aviation aircraft
since heading has a low safety criticality relative to altitude,
attitude, and airspeed for this class of airplane. The FAA disagrees
since an additional or separate display is not required if there are
two independent power sources. Heading is an important parameter, and
Sec.  91.205 requires a stabilized heading source for IFR operations,
in addition to the magnetic direction indicator.
    Proposed amendments for storage battery design and installation in
Sec.  23.1353 would have added additional battery endurance
requirements to enhance safety based on the airplane's altitude
performance. The proposal addressed the power needs of new all-
electrical instruments, navigation and communications equipment, and
engine controls.
    When those requirements were initially adopted, part 23 airplanes
were mostly mechanical. All-electric, or almost all-electric airplanes
were not envisioned. Previously, the FAA required 30 minutes of
sufficient electrical power for a reduced or emergency group of
equipment and instrumentation. The FAA 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.
    Integrated electrical cockpits were also not envisioned during
initial development of those requirements. Currently, new part 23
airplanes are being certificated with all-electrical instruments,
including the standby instruments. This reliance on electric power has
increased the importance of ensuring adequate battery power until the
pilot can descend and make a safe landing.
    Most new turbine-powered airplanes, and some turbocharged, piston-
powered airplanes, operate at high altitudes under IFR. Under these
conditions, 30 minutes may not be adequate for battery power because it
would take more time 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, the proposed requirement
would extend the battery time requirement to 60 minutes for approved
airplanes with a maximum operating altitude above 25,000 feet. The 30
minute battery capacity was retained for airplanes with a maximum
operating altitude of 25,000 feet or less.
    We received five comments on this issue. Cessna, Diamond, and GAMA
stated that the 60-minute battery capacity should not be required. They
suggested a requirement to demonstrate descent and landing plus 10
minutes. Cirrus recommended a second energy source instead of a 60-
minute battery. EASA suggested including the time to recognize the
failure and take load shedding action, which was inadvertently omitted
in the NPRM.
    The FAA disagrees with the Cessna, Diamond, and GAMA's comments.
While jets often have speed brakes and a high dive speed, the rule
requires descent and landing. Jets also typically have high stall
speeds, which may limit the number of airports where they can safely
land, and off-airport landing capability is minimal. There are also
piston-powered airplanes that operate above 25,000 feet with
turbocharging, which do not have the dive speed and speed brakes often
installed in jets. All of these airplanes can operate in IMC, which can
delay the landing. Thus, the 60-minute battery capacity is valid for
higher performance aircraft that operate above 25,000 feet.
    The FAA also disagrees with Cirrus that a separate power source is
superior to a 60-minute battery. Single- or dual-power sources are not
causes for concern because the intent of Sec.  23.1353(h) is to assume
the loss of all generated power.
    There was not a proposal in the NPRM to revise Sec.  23.1431,
electronic equipment, but editorial changes have become necessary since
there were paragraph designation changes in Sec.  23.1309.
    We proposed changing requirements in Sec.  23.1443 for minimum mass
flow of supplemental oxygen. The FAA has addressed oxygen systems for
airplanes operating above 41,000 feet using special conditions derived
from part 25. A large number of new jets and high-performance airplanes
applying for part 23 certification operate at higher altitudes than
previously envisioned for part 23 airplanes. Proposed revisions would
establish requirements for those oxygen systems. These proposed
revisions would also eliminate the need for oxygen system special
conditions for airplanes with maximum operating altitudes above 41,000
feet.
    Cessna and EASA stated that the proposed rule conflicted with
another rule for crew oxygen equipment since a continuous oxygen system
is unacceptable for the crew at that altitude. The FAA agrees and has
modified Sec.  23.1443(a) to apply continuous flow oxygen systems only
to passengers for operations above 41,000 feet as required by Sec.
23.1441(d).

J. Placards, Operating Limitations, and Information

    Proposed revisions to airspeed limitations in Sec.  23.1505(c)
would include jet-specific V-speeds. This proposal would base airspeed
limits on a combination of analytical (VD/MD) and
demonstrated (VDF/MDF) dive speeds for jets.
    The FAA received one comment from EASA. EASA stated that it applies
a special condition for high-speed characteristics not included in our
proposal. Again, EASA's comment suggests performance-based standards.
Amending part 23 to a performance-based standard is a substantially
larger initiative than this rulemaking effort.
    The FAA also proposed amendments that were clarifying in nature so
applicants would understand that they may need additional equipment for
their airplane(s) to conduct part 135 operations. Part 23 is a minimum-
performance standard, and it may not include all the required equipment
for operations under part 135. Proposed revisions to Sec.  23.1525
would include parts 91 and 135 as potential kinds of authorized
operation.
    The FAA received comments from Transport Canada, Embraer, Cirrus,
and Diamond. All four commenters stated that the operating rules should
not be referenced in part 23. There was concern the proposed revisions
could be misinterpreted and increase the certification burden to
manufacturers. We do not intend to add any burden to manufacturers. We
simply wanted to remind them that in many cases, part 135 operations
require additional equipment not typically installed as standard
equipment in part 23 airplanes. However, in light of those comments,
this proposal is withdrawn.
    The FAA proposed revising Sec. Sec.  23.1583(c)(3), 23.1583(c)(4),
and 23.1583(c)(5), operating limitations; Sec.  23.1585(f), operating
procedures; and Sec.  23.1587(d) performance information by applying
most commuter category performance requirements to jets weighing over
6,000 pounds. The proposed AFM requirements would maintain consistency
with the

performance requirements proposed in Subpart B. These requirements
include the single-engine climb performance increase for turboprops.
    The FAA received three comments, one from EASA, Diamond, and
Transport Canada. EASA states that it requires a special condition for
landing distance factors not included in our proposal. This comment is
outside the scope of this rulemaking effort. Diamond questioned the
distinction between turbines and high-performance piston airplanes. The
FAA agrees conceptually with these comments, but they are also beyond
the scope of this rulemaking effort. Transport Canada stated that part
23 jets should include data for wet and contaminated runways. The
upcoming part 23 regulatory review for future rulemaking will consider
performance data.

K. Test Procedure and Appendices

    The FAA proposed changing Appendix F, which is the test procedure
for the requirement in Sec.  23.856. GE asked if the test procedure was
new. The test procedure is not new; Appendix F modifications made new
part 23, Appendix F, part II, identical to part 25, Appendix F, part
VI. GAMA questioned the use of a brand name in the discussion of
Appendix F, Figure F1. In response, we reaffirm the use of the brand
name as adopted from part 25, Appendix F. Again, our efforts toward
standardization should be maintained wherever appropriate in our
requirements. Appendix F is adopted as proposed.

III. Regulatory Analyses

Paperwork Reduction Act

    The Paperwork Reduction Act of 1995 (44 U.S.C. 3507(d)) requires
that the FAA consider the impact of paperwork and other information
collection burdens imposed on the public. The FAA has determined that
there is no new requirement for information collection associated with
this final rule.

International Compatibility

    In keeping with U.S. obligations under the Convention on
International Civil Aviation, it is FAA policy to conform to
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 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 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 final rule. Readers seeking greater detail
should read the full regulatory evaluation, a copy of which we have
placed in the docket for this rulemaking.
    In conducting these analyses, the FAA has determined that this
final 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) is ``significant'' as defined in
DOT's Regulatory Policies and Procedures; (4) will not have a
significant economic impact on a substantial number of small entities;
(5) will not create unnecessary obstacles to the foreign commerce of
the United States; and (6) will 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 cost of this final rule ranges from a low of $65.2
million to a high of $72.9 million in nominal dollars ($22.9 million to
$26.7 million at a seven percent present value).
    The total benefits are equal to the sum of the safety and
efficiency benefits. The estimated safety benefits of avoiding 26
accidents on newly certificated part 23 airplanes over the 57-year
analysis interval are estimated at about $187.1 million in nominal
dollars ($46.5 million at a seven percent present value).
    The estimated efficiency benefits to streamline the part 23
certification process are valued at about $965 thousand, in nominal
dollars, for five special conditions per aircraft certification, to
about $1.5 million, in nominal dollars, for eight special conditions
per aircraft certification. The total benefits range from a low of
about $188.1 million to high of about $188.6 million in nominal
dollars. The following table shows these results.
[GRAPHIC] [TIFF OMITTED] TR02DE11.078

Who is Potentially Affected by This Rule
    This rulemaking will affect U.S. manufacturers and operators of
part 23 turbojets, turboprops, and reciprocating engine airplanes.
Assumptions
    This final rule makes the following assumptions:
     The base year is 2010;

     The average life of a U.S.-operated part 23 airplane is 32
years;
     The average part 23 airplane production life cycle is 25
years;
     The analysis period extends for 57 years (32 + 25); and
     The value of a fatality avoided is $6.0 million.
Benefits of This Rule
    The FAA estimates the final rule will avoid 26 accidents over the
32-year operating life of 29,725 newly certificated and delivered part
23 airplanes. The resulting benefits include standardizing and
streamlining the certification process, averted fatalities and
injuries, loss of airplanes, investigation cost, and collateral damages
for the accidents.
    The safety benefits for averting the 26 accidents are about $187.1
million in nominal dollars ($46.5 million at a seven percent present
value). Other benefits of this final rule include FAA and industry
paperwork and certification time saved by standardizing and
streamlining the certification of part 23 airplanes. These efficiency
benefits for standardizing and streamlining the certification process
range from a low estimate of about $965 thousand to a high estimate of
$1.5 million in nominal dollars.
    The total benefits are equal to the sum of the safety and
efficiency benefits and range from a low of about $188.1 million to
high of about $188.6 million in nominal dollars.
Costs of This Rule
    Estimated nominal dollar unit costs per part 23 airplane could be
as high as: $1,009 for reciprocating engine airplanes, $6,105 for
turboprops, and $8,053 for turbojets. Total incremental costs equal the
nominal dollar unit costs multiplied by the number of newly
certificated airplanes produced and delivered over the analysis
interval. The estimated cost of this final rule ranges from a low of
$65.2 million to high of $72.9 million in nominal dollars ($22.9
million to $26.7 at a seven percent present value).
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; and
     Alternative 2--The FAA would continue to enforce the
current regulations that affect single-engine climb performance and
power loss. The FAA rejected this alternative because the accident rate
for part 23 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 has determined that this final rule will not have a
significant impact on a substantial number of small entities. The
purpose of this analysis is to provide the reasoning underlying the
FAA's determination.
    The FAA made the same determination that this proposal would not
have a significant impact on a substantial number of small entities in
the notice of proposed rulemaking (NPRM). The only comment regarding
small entities for the NPRM was Sino Swearingen, who requested we note
that it is now Emivest Aerospace, which is foreign owned.
    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 rule. Next we explain there are no relevant federal
rules which may overlap, duplicate, or conflict with the final rule.
Lastly, we will describe and provide an estimate of the number of small
entities affected by the final rule and why the FAA believes this final
rule will 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 proposed this action to amend safety and applicability
standards for part 23 turbojets to reflect the current needs of the
industry, accommodate future trends, address emerging technologies, and
provide for future aircraft operations. This final rule primarily
standardizes and streamlines the certification of part 23 turbojets.
The changes to part 23 are necessary to eliminate the current workload
of exemptions, special conditions, and equivalent levels of safety
necessary to certificate part 23 turbojets. These 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 turbojets, turboprops, 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
certification programs. However, in the past seven years, the number of
new part 23 turbojet certification programs has increased by more than
100 percent when compared to over the past three decades.
    The need to incorporate these special conditions into part 23 stems
from both the existing number of new turbojet certification programs
and the expected number of future turbojet programs. Codifying these
special conditions will allow manufacturers to know the requirements
during the 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 type certificate an airplane and reduces the
potential for program delays. These final rule changes will also
clarify areas of frequent non-standardization and misinterpretation,
particularly for electronic equipment and system certification on all
newly certificated part 23 airplanes.
    The revisions include general definitions, error corrections, and
specific requirements for performance and handling characteristics to
ensure safe operation of part 23 airplanes. The revisions will apply to
all future new part 23 turbojets, turboprops, and

reciprocating engine airplane certifications.
    We now discuss the legal basis for, and objective of, the rule.
Next, we discuss if there are relevant federal rules that may overlap,
duplicate, or conflict with the 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 final rule will amend Title 14, the Code of
Federal Regulations to address deficiencies in current regulations
regarding the certification of part 23 light turbojets, turboprops and
reciprocating engine airplanes. The final rule will also clarify areas
of frequent non-standardization and misinterpretation and codify
certification requirements that currently exist in special conditions.
    The rule will not overlap, duplicate, or conflict with existing
federal rules.
    We now discuss our methodology to determine the number of small
entities for which the rule will apply.
    Under the RFA, the FAA must determine whether a proposed or final
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.\2\
---------------------------------------------------------------------------

    \2\ 13 CFR 121.201, Size Standards Used to Define Small Business
Concerns, Sector 48-49 Transportation, Subsector 481 Air
Transportation.
---------------------------------------------------------------------------

    There are nine U.S.-owned aircraft manufacturers who deliver part
23 airplanes in the 1998-2009 analysis interval. These manufacturers
are American Champion, Cessna, Cirrus, Hawker Beechcraft, Liberty,
Maule, Mooney, Piper, and Quest.
    Using information provided by the World Aviation Directory,
Internet filings and industry contacts, manufacturers that are
subsidiary businesses of larger businesses, manufacturers that are
foreign owned, and businesses with more than 1,500 employees were
eliminated from the list of small 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 final rule is 2010. Although the FAA
forecasts traffic and air carrier fleets, we cannot determine the
number of new entrants, nor who will be in the part 23 aircraft
manufacturing business in the future. Therefore we use current U.S.
part 23 aircraft manufacturers' revenue and employment in order to
determine the number of operators this final rule will affect.
    The methodology discussed above resulted in the following list of
four U.S. part 23 aircraft manufactures, with less than 1,500
employees.
[GRAPHIC] [TIFF OMITTED] TR02DE11.079

    From the list of small entity U.S. airplane manufacturers above,
there are no manufacturers currently producing part 23 turbojets; only
Piper and Quest produce turboprops. The remaining small entity U.S.
aircraft manufacturers produce part 23 reciprocating engine airplanes.
    The U.S. Census Bureau data on the Small Business Administration's
Web site shows an estimate of the total number of small entities who
could be affected if they purchase newly certificated part 23
airplanes. 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 subject to part
25. Other small businesses may own aircraft and not be included in the
U.S. Census Bureau Non-scheduled Air Transportation Industry
category.\3\ Therefore, we will use the list of small entities from
Table RF1 instead of the U.S. Census Bureau data for our Final
Regulatory Flexibility Act (FRFA) analysis.
---------------------------------------------------------------------------

    \3\ http://www.sba.gov/advo/research/us05_n6.pdf.
---------------------------------------------------------------------------

    We will now develop the estimate of the effect of this final rule
on the total number of small entities that manufacture part 23
airplanes.
    First, we discuss our methodology to estimate the costs of the
final rule to the small entity part 23 airplane manufacturers and
operators. Next, we will discuss why the FAA believes the final rule
will 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). The FAA and the part 23
industry have worked together to develop common part 23 airplane
certification requirements for this rulemaking. We contacted the part
23 aircraft manufacturers, the ARC, and GAMA (an industry association
for part 23 aircraft manufacturers) for specific cost estimates for
each section change for the final 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 the proposed rule.
    We are basing our cost estimates for this final rule from data
provided by the domestic part 23 U.S. aircraft manufacturers, ARC
members, and GAMA. They informed us that the final

rule will add costs for fire extinguishing systems, climb, take-off
warning systems, ventilation systems, system designs, and batteries.
Industry informed us that this proposal will save the manufacturers
design time for the certification of cockpit controls. Industry has
also informed us that every other section of this final rule is either
clarifying, error correcting, or will only add minimal to no costs.
    The final rule adds certification requirements for the following
part 23 airplane categories:
    1. Turbojets;
    2. Turbojets with a MTOW less than 6,000 pounds;
    3. Turboprops;
    4. Turboprops with a MTOW less than 6,000 pounds;
    5. Reciprocating engine airplanes; and
    6. Reciprocating engine airplanes with a MTOW greater than 6,000
pounds.
    In some cases the final rule will 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 the personal use of a part 23 airplane
by analyzing the number of all U.S.-operated airplanes from Table 3.1
of the 2008 General Aviation and Part 135 Activity Survey.
    Table 3.1 of that survey shows the breakout of the 2008 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 2008 General Aviation and Part 135 Activity Survey
will operate in commuter service.
    Table RF2 shows these results:
    [GRAPHIC] [TIFF OMITTED] TR02DE11.080

    Table RF3 shows the final rule sections that add (or subtract)
incremental costs by increasing design or flight testing times, adding
weight, adding batteries, or reducing payload:
[GRAPHIC] [TIFF OMITTED] TR02DE11.081

    We estimated part 23 airplane fixed manufacturer (added
certification plus flight test hours) and operator-variable flight
operation (added weight, batteries, or a reduction in payload) costs
and applied our estimated costs to the expected fleet delivered in
compliance with this final rule. The total cost of this final rule is
the sum of the fixed certification cost plus the variable flight
operation cost multiplied by the expected newly certificated part 23
fleet delivered over the analysis interval.
    The total fixed certification compliance cost equals the industry-
provided incremental hours or dollar costs multiplied by the expected
number of new certifications for part 23 turbojets, turboprops, and
reciprocating engine airplanes.
    The total variable flight operation compliance cost equals the
industry-provided incremental weight, payload reduction, or dollar
costs multiplied by the expected number of newly certificated part 23
turbojets, turboprops, and reciprocating engine airplanes delivered. In
the regulatory analysis, we estimated a low case and a high case cost
range for the fixed operation compliance costs. The range was based on
the 10% loss in payload capacity noted in Table RF3.
    In the low case, we estimated no loss in capacity because our
analysis showed that part 23 airplanes operate well below the
airplane's payload capacity. In the high case, we estimated a cost to
operators for the 10% loss in payload capacity. We will use the high-
variable, flight operation cost scenario for this FRFA analysis.
    We estimated the nominal dollar unit costs for all part 23
airplanes by summing the fixed certification costs

with the variable flight operations compliance costs by part 23
turbojets, turboprops, and reciprocating engine airplanes. Next, we
divided these sums by the number of newly certificated delivered part
23 turbojets, turboprops, and reciprocating engine airplanes. Our
calculations yielded that unit costs could be as high as $1,009 for
newly certificated reciprocating engine airplanes and $6,105 for
turboprop airplanes.
    We then took the product of the estimated unit airplane cost with
the average annual number of part 23 turbojets, turboprops, and
reciprocating engine airplanes that each of the four small business
part 23 manufacturers (from Table RF1) delivered from 1998 to 2009.
This product determined the annual impact of the final rule to each
small business part 23 manufacturer. Lastly, we divided each small part
23 airplane manufacturer's annual revenue by the incremental costs.
    Table RF4 shows these results:
    [GRAPHIC] [TIFF OMITTED] TR02DE11.082

    We do not believe that these final rule costs will 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 less
than one percent of annual revenue for each of the small business part
23 manufacturers. Again, the only comment regarding small entities for
the NPRM was the noted comment from Sino Swearingen.
    Therefore, as the FAA Administrator, I certify that this final rule
will not have a significant economic impact on a substantial number of
small entities.

International Trade Impact Assessment

    The Trade Agreements Act of 1979 (Pub. L. 96-39), as amended by the
Uruguay Round Agreements Act (Pub. L. 103-465), prohibits Federal
agencies from establishing standards or engaging in related activities
that create unnecessary obstacles to the foreign commerce of the United
States. Pursuant to these Acts, the establishment of standards is not
considered an unnecessary obstacle to the foreign commerce of the
United States, so long as the standard has a legitimate domestic
objective, such as the protection of safety, and does not operate in a
manner that excludes imports that meet this objective. 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
determined that the standards are necessary for aviation safety and
will not create unnecessary obstacles to the foreign commerce of the
United States.

Unfunded Mandates Assessment

    Title II of the Unfunded Mandates Reform Act of 1995 (Pub. L. 104-
4) requires each Federal agency to prepare a written statement
assessing the effects of any Federal mandate in a proposed or final
agency rule that may result in an expenditure of $100 million or more
(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 $140.8
million in lieu of $100 million. This final 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 final rule under the principles and
criteria of Executive Order 13132, Federalism. We determined that this
action will not have a substantial direct effect on the States, or the
relationship between the Federal Government and the States, or on the
distribution of power and responsibilities among the various levels of
government; therefore, it does not have federalism implications.

Regulations Affecting Intrastate Aviation in Alaska

    Section 1205 of the FAA Reauthorization Act of 1996 (110 Stat.
3213) requires the FAA, when modifying its 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. In the NPRM, we
requested comments on whether the proposed rule should apply
differently to intrastate operations in Alaska. We did not receive any
comments. We have determined, based on the administrative record of
this rulemaking, that there is no need to make any regulatory
distinctions applicable to intrastate aviation 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 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 analyzed this final rule under Executive Order 13211,
Actions Concerning Regulations that Significantly Affect Energy Supply,
Distribution, or Use (May 18, 2001). We have determined that it is not
a ``significant energy action'' under the executive order because it is
not a ``significant regulatory action,'' and it is not likely to have a
significant adverse effect on the supply, distribution, or use of
energy.

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 notice, amendment, or docket
number of this rulemaking.
    Anyone is able to search the electronic form of all comments
received into any of our dockets by the name of the individual
submitting the comment (or by signing the comment, if submitted on
behalf of an association, business, labor union, etc.). You may review
DOT's complete Privacy Act statement in the Federal Register published
on April 11, 2000 (Volume 65, Number 70; Pages 19477-78) or you may
visit http://DocketsInfo.dot.gov.

Small Business Regulatory Enforcement Fairness Act

    The Small Business Regulatory Enforcement Fairness Act (SBREFA) of
1996 requires FAA to comply with small entity requests for information
or advice about compliance with statutes and regulations within its
jurisdiction. If you are a small entity and you have a question
regarding this document, you may contact your local FAA official, or
the person listed under the FOR FURTHER INFORMATION CONTACT heading at
the beginning of the preamble. You can find out more about SBREFA on
the Internet at http://www.faa.gov/regulations_policies/rulemaking/sbre_act/.

List of Subjects in 14 CFR Part 23

    Aviation safety, Signs, Symbols, Aircraft.

The Amendments

    In consideration of the foregoing, the Federal Aviation
Administration amends Chapter I of Title 14, Code of Federal
Regulations, as follows:

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

0
1. The authority citation for part 23 continues to read as follows:

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

0
2. 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. * * *
* * * * *

0
3. Amend Sec.  23.45 by revising the introductory text of paragraph (h)
to read as follows:

Sec.  23.45  General.

* * * * *
    (h) For multiengine jets weighing over 6,000 pounds in the normal,
utility, and acrobatic category and commuter category airplanes, the
following also apply:
* * * * *

0
4. 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--
* * * * *

0
5. 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 jets of
more than 6,000 pounds maximum weight and commuter category airplanes,
the following apply:
* * * * *

0
6. 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 jets 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.

0
7. 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 jets of
more than 6,000 pounds maximum weight and commuter category airplanes,
the accelerate-stop distance must be determined as follows:
* * * * *

0
8. 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 jets of
more than 6,000 pounds maximum weight and commuter category airplanes,
the takeoff path is as follows:
* * * * *

0
9. 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 jets 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.
* * * * *

0
10. 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 jets of
more than 6,000 pounds maximum weight and commuter category airplanes,
the takeoff flight path must be determined as follows:
* * * * *

0
11. 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 and ambient temperature within the operational
limits established for takeoff and landing, respectively, with--
* * * * *

0
12. Amend Sec.  23.65 by revising paragraph (b) to read as follows:

Sec.  23.65  Climb: All engines operating.

* * * * *
    (b) Each normal, utility, and acrobatic category reciprocating
engine-powered airplane of more than 6,000 pounds maximum weight,
single-engine turbine, and multiengine turbine airplanes of 6,000
pounds or less maximum weight in the normal, utility, and acrobatic
category must have a steady gradient of climb after takeoff of at least
4 percent with
* * * * *

0
13. Amend Sec.  23.67 by revising paragraph (b) introductory text and
(b)(1) introductory text, redesignating paragraph (c) as paragraph (d),
revising newly redesignated paragraph (d) introductory text, and adding
new paragraph (c) to 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 must be no less than 1 percent with the--
* * * * *
    (c) For normal, utility, and acrobatic category jets of 6,000
pounds or less maximum weight--
    (1) The steady gradient of climb at an altitude of 400 feet above
the takeoff must 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 jets over 6,000 pounds maximum weight in the normal,
utility and acrobatic category and commuter category airplanes, the
following apply:
* * * * *

0
14. 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