[Federal Register Volume 88, Number 64 (Tuesday, April 4, 2023)]
[Rules and Regulations]
[Pages 19801-19811]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-06413]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 33
[Docket No.: FAA-2018-0568; Amdt. No. 33-36]
RIN 2120-AK83
Medium Flocking Bird Test at Climb Condition
AGENCY: Federal Aviation Administration (FAA), Department of
Transportation (DOT).
ACTION: Final rule.
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SUMMARY: This final rule adds new test requirements to the
airworthiness regulation addressing engine bird ingestion. The new test
requirements ensure that turbofan engines can ingest
[[Page 19802]]
the largest medium flocking bird (MFB) into the engine core at climb or
approach conditions. To obtain certification of a turbofan engine, a
manufacturer must show the engine core can continue to operate after
ingesting such a bird while operating at a lower fan speed associated
with climb or approach.
DATES: Effective June 5, 2023.
ADDRESSES: For information on where to obtain copies of rulemaking
documents and other information related to this final rule, see ``How
To Obtain Additional Information'' in the SUPPLEMENTARY INFORMATION
section of this document.
FOR FURTHER INFORMATION CONTACT: Philip Haberlen, Federal Aviation
Administration, Propulsion and Energy Section, Technical Innovation
Policy Branch, Policy & Innovation Division, Aircraft Certification
Services AIR 624, 1200 District Avenue, Burlington, Massachusetts
01803-5213; telephone (781) 238-7770; fax (781) 238-7199; email:
[email protected].
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
Title 49, Subtitle VII, Part A, Subpart III, Section 44701, General
requirements. Under that section, the FAA is charged with promoting
safe flight of civil aircraft in air commerce by prescribing minimum
safety standards required in the interest of safety for performance of
aircraft engines. This regulation is within the scope of that authority
because it creates new safety-related testing requirements for
certification of aircraft turbofan engines.
I. Executive Summary
A. Overview of Final Rule
The FAA is amending the airworthiness regulations related to engine
bird ingestion testing in part 33 of title 14, Code of Federal
Regulations (14 CFR) (notice of proposed rulemaking (NPRM) published at
83 FR 31479 on July 6, 2018). This final rule revises Sec. 33.76 to
create an additional bird ingestion test for turbofan engines. This new
test ensures that engines can ingest the largest MFB required for bird
ingestion testing into the engine core \1\ at climb conditions. If the
engine design is such that no bird material would be ingested into the
engine core during the test at climb conditions, then the rule requires
a different test at approach conditions.
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\1\ Turbofan engines have fan and core compressor sections. The
fan or low-pressure compressor is at the front of the engine. The
core consists of additional compressor stages behind the fan. Each
compressor stage consists of a rotating row of blades and a
stationary row of vanes.
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The new testing required by this final rule consists of ingesting
one MFB, equivalent to the largest bird required by Sec. 33.76(c), for
the engine inlet throat area of the engine being tested,\2\ into the
engine core, using either of the following climb or approach test
conditions:
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\2\ Section 33.76(c) addresses small and medium bird ingestion
requirements.
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(1) Testing for bird ingestion on climb (referred to in this final
rule as ``climb flocking bird test''). The test bird must be fired at
261-knots (which is 250-knots indicated airspeed (KIAS)), with the
mechanical engine fan speed set at the lowest expected speed when
climbing through 3,000 feet altitude above mean sea level at
International Standard Atmosphere (ISA) standard day conditions
(hereafter referred to as MSL). After bird ingestion, the engine must
comply with new post-test run-on requirements similar to those in Sec.
33.76(d)(5) for large flocking birds, except that, depending on the
climb thrust of the engine, during the first minute after bird
ingestion the engine may produce less than 50 percent takeoff thrust.
(2) Testing for bird ingestion on approach (referred to in this
final rule as ``approach flocking bird test''). If the applicant
determines, through testing or validated analysis, that no bird
material will enter the core during the test at the climb condition,
then the applicant must perform the approach flocking bird test. For
the approach flocking bird test, the bird must be fired at 209-knots
(which is 200-KIAS), with the mechanical engine fan speed set at the
lowest fan speed expected when descending through 3,000 feet MSL on
approach. Applicants are required to comply with post-test run-on
requirements that are the same as the final six minutes of Sec.
33.76(d)(5) post-test run-on requirements for the large flocking bird
(LFB) test. While the FAA based the approach run-on requirements of
this final rule on the LFB post-test run-on requirements, only the last
six minutes of the test is required, since during approach the airplane
will already be lined up with the runway.
Additionally, this final rule allows the climb flocking bird test
to be combined with the Sec. 33.76(c) test when the climb first stage
(fan) rotor speed is no more than three percent different from the
first stage rotor speed, as required by Sec. 33.76(c)(1). This allows
manufacturers of engines for airplanes, where the pilot does not pull
back on the throttle during climb, to perform one fewer ingestion test.
Since the fan rotor speed during climb will be the same as the fan
rotor speed at takeoff thrust, the amount of bird material ingested
into the core during the climb flocking bird test will depend on bird
speed and not fan speed.
This final rule also allows the applicant to use objects other than
birds to meet the new test requirements.
B. Summary of Costs and Benefits
Over a 27-year period of analysis, the rule will result in present
value net benefits of about $9.7 million at a seven percent discount
rate with annualized net benefits of about $0.8 million. At a three
percent discount rate, the 27-year present value net benefits is about
$36.2 million with annualized net benefits of about $1.9 million.
The following table presents estimates of the quantified benefits,
costs, and net benefits of the rule.
Summary of Benefits, Costs, and Net Benefits
[$Millions]
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27-Year total 27-Year total
present value present value Annualized 7% Annualized 3%
Impact 7% present 3% present present value present value
value value
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Benefits........................................ $73.7 $121.6 $6.1 $6.6
[[Page 19803]]
Costs........................................... 64.0 85.4 5.3 4.7
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Net Benefits................................ 9.7 36.2 0.8 1.9
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II. Background
A. Statement of the Problem
On January 15, 2009, US Airways Flight 1549 (Flight 1549), an
Airbus A320, took off from La Guardia Airport in New York City. On
climb, at approximately 2,800 feet above ground level (AGL) and
approximately 230-KIAS, the airplane struck a flock of migratory Canada
geese. Both of the airplane's engines ingested at least two birds, and
both engine cores suffered major damage and total thrust loss.
The A320 series of airplanes (i.e., A318/A319/A320/A321) and the
similarly sized Boeing 737 series of airplanes are among the airplanes
most frequently used by air carriers.\3\ Most transport airplanes
(including the A320) and many business jets use turbofan engines that
are susceptible to bird ingestion damage, which, in some instances, has
resulted in loss of greater than 50 percent takeoff thrust. In twin-
engine airplanes, this amount of thrust loss in both engines can
prevent the airplane from climbing over obstacles or maintaining
altitude. Significant loss of thrust by more than one engine is a
hazardous condition because it can prevent continued safe flight and
landing.
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\3\ https://www.faa.gov/data_research/aviation/aerospace_forecasts/media/FY2019-39_FAA_Aerospace_Forecast.pdf, pp
31-32, ``U.S. Commercial Aircraft Fleet.''
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As a result of the Flight 1549 accident, the FAA began studying how
to improve engine durability related to core engine bird ingestion.\4\
In response to a tasking from the FAA to review and study bird
ingestion standards and guidance, the Aviation Rulemaking Advisory
Committee (ARAC) established the Engine Harmonization Working Group
(EHWG) under the Transport Airplane and Engine subcommittee. The EHWG
developed a report, subsequently accepted by the ARAC, titled
``Turbofan Bird Ingestion Regulation Engine Harmonization Working Group
Report'' (ARAC report), dated February 19, 2015.\5\ The ARAC report
concluded that modern fan blades (such as those on the Flight 1549
airplane engines) have relatively wider fan blade chords than those in-
service when the FAA implemented the MFB ingestion test in 14 CFR
33.76(c) (65 FR 55848, September 14, 2000). The ARAC report also
pointed out that the Sec. 33.76(c) test is conducted with the engine
operating at 100 percent takeoff power or thrust. This setting is ideal
for testing the fan blades but does not represent the lower fan speeds
used during the climb and approach phases of aircraft flight.
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\4\ The FAA used the following studies to begin the review: FAA
Technical Center Report DOT/FAA/AR-TN03/60, ``Study of Bird
Ingestions Into Aircraft Turbine Engines (December 1968-December
1999),'' September 2003, and the ``Aerospace Industries Association
(AIA) Bird Ingestion Working Group Interim Report--January 2012,''
produced after the Flight 1549 accident. The AIA report contains the
latest bird ingestion data available through January 2009, including
data from the Flight 1549 accident. The FAA included both reports in
the docket for this rulemaking.
\5\ The FAA included the ARAC report in the docket for this
rulemaking. This rulemaking is consistent with the recommendations
in the report.
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When an engine ingests a bird, the amount of bird material that
enters the engine core depends on: (1) the width of the fan blade
chord, (2) the airplane's speed, and (3) the rotational speed of the
fan blades. The wider the chord of the fan blade and the lower the
speed of the airplane, the longer the bird will remain in contact with
the fan blade. As airplane speed increases, the bird spends less time
on the fan blade. With higher fan speed, the bird will move radially
faster away from the core. Thus, the longer the time in contact with
the fan blade, from wider blades and lower airspeed, and increased
centrifugal forces from a higher fan speed, the further outboard and
away from the core the bird material will move. Therefore, a higher fan
speed makes it less likely that bird material will enter the core
during the Sec. 33.76(c) test compared to the new climb flocking bird
test. Conversely, a lower fan speed and higher airspeed, for a given
fan blade width, make it more likely that the bird material will enter
the core.
The Sec. 33.76(c) test is conducted using 100 percent power or
thrust and the most critical airspeed up to 1,500 feet AGL.
Consequently, the Sec. 33.76(c) test does not simulate lower fan speed
phases of flight (such as climb and descent) during which a bird, if
ingested, is more likely to enter the engine core. In addition, the
higher airspeed in climb is not covered by the Sec. 33.76(c) test.
Therefore, the small and medium flocking bird test prescribed in Sec.
33.76(c) does not fully provide the intended demonstration of core
durability against bird ingestion for the climb and approach
conditions.
B. National Transportation Safety Board (NTSB) Recommendations
As part of its report \6\ on Flight 1549, the NTSB issued two
relevant engine-related safety recommendations to the FAA:
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\6\ Loss of Thrust in Both Engines After Encountering a Flock of
Birds and Subsequent Ditching on the Hudson River, US Airways Flight
1540, Airbus A320-214, N106US, Weehawken, New Jersey, January 15,
2009, Aircraft Accident Report NTSB/AAR-10/03 (Washington, DC: NTSB,
2009) (hereinafter ``NTSB report AAR-10/03'' available at https://www.ntsb.gov/investigations/Pages/DCA09MA026.aspx.
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(1) A-10-64: Modify the small and medium flocking bird
certification test standard to require that the test be conducted using
the lowest expected fan speed, instead of 100 percent fan speed, for
the minimum climb rate.
(2) A-10-65: During re-evaluation of the current engine bird-
ingestion certification regulations by the Bird Ingestion Rulemaking
Database working group, specifically re-evaluate the large flocking
bird certification test standards to determine if they should:
(a) Apply to engines with an inlet area of less than 2.5 square
meters (3,875 square inches).
(b) Include an engine core ingestion requirement.
If re-evaluation determines the need for these requirements,
incorporate them into 14 CFR 33.76(d) and require that newly
certificated engines be designed and tested to these requirements.
The ARAC report addressed both NTSB safety recommendations. In
response to NTSB safety recommendation A-10-64, the ARAC
[[Page 19804]]
report recommended the test adopted in this final rule. The ARAC report
found that its recommendation would also address the intent of NTSB
safety recommendation A-10-65 since the kinetic energy of the bird in
this final rule is of the same magnitude as a LFB test.
III. Discussion of Public Comments and Final Rule
The FAA received comments on the NPRM from 12 commenters.
Specifically, the FAA received comments from Pratt & Whitney U.S.A.
(Pratt & Whitney); Honeywell International; Pratt & Whitney Canada
Corporation (Pratt & Whitney Canada); The Boeing Company; General
Electric (GE); Aerospace Industries Association (AIA); Rolls-Royce; Air
Line Pilots Association, International (ALPA); the National
Transportation Safety Board (NTSB), and three individuals. The FAA
received supportive comments on the NPRM from the NTSB and one
individual. While a number of commenters requested changes, commenters
generally supported the proposal. The NTSB expressed general support
for the NPRM and noted the proposed rule, when implemented, would
satisfy the intent of NTSB Safety Recommendation A-10-64.\7\
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\7\ NTSB further stated in its comment that, ``Recommendation A-
10-65 was classified ``Closed--Acceptable Action'' on March 1, 2016,
in part because the ARAC found that the new climb condition MFB test
will further assure the robustness of the engine core.''
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A. Fan Speed Difference Criteria for Combining the Existing MFB Test
(Sec. 33.76(c)) and the New Climb Flocking Bird Test (Sec.
33.76(e)(1))
In the NPRM, the FAA proposed allowing applicants to combine the
new climb flocking bird test with the existing Sec. 33.76(c) test if
the fan speed at climb is within 1 percent of the fan speed at takeoff.
The purpose of the proposed 1 percent limit on the difference between
the climb and takeoff fan speed was to ensure the combined test would
apply only to engines designed such that the typical operational
practice will be to maintain the throttle in the takeoff position
through the climb phase. However, even with the throttle in the same
position, both fan and core rotor speeds will change to some extent
with altitude and aircraft speed.
AIA, Pratt & Whitney, Pratt & Whitney Canada, Honeywell
International, The Boeing Company, GE, and one individual commented on
the proposed allowance for combining the new test with the Sec.
33.76(c) test. These commenters stated the proposed one percent
difference in fan rotor speed at takeoff and climb conditions in Sec.
33.76(e)(4) is too restrictive. Commenters further stated the in-
service difference between climb and takeoff fan rotor speeds is in the
range of three percent to five percent, and recommended the FAA allow
applicants to combine the tests when the fan rotor speed difference was
no greater than three percent.
This final rule allows combining the MFB test and the new test at
climb condition when the difference in the climb and takeoff fan rotor
speeds is no more than three percent. The NTSB accident report for the
Flight 1549 accident states that Flight 1549 impacted birds at
approximately 2,800 feet altitude AGL and ~82 percent fan speed; well
below the maximum takeoff setting.\8\ The ARAC report states that many
air carriers operating transport category airplanes use reduced thrust
or derated takeoff power settings. Operators may use reduced thrust or
derated takeoff power settings because they may provide substantial
benefits in terms of engine reliability, maintenance, and operating
costs, while operating at lower fan speeds than the maximum takeoff
thrust rating. Climb power settings on large transport airplanes are
also significantly lower than maximum takeoff settings. Smaller jet
aircraft with small throat inlets are not typically certified to
perform reduced thrust or derated takeoffs (i.e., all takeoffs are
completed at max rated takeoff thrust), and climb power settings on
most smaller corporate aircraft are typically close to the maximum
takeoff thrust rating.
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\8\ NTSB report AAR-10/03 at paragraph 2.8.1, page 98, and
paragraph 1.16.1, page 47.
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The FAA agrees with the commenters' recommendation to allow
combining the new climb flocking bird test with the existing MFB test
in Sec. 33.76(c) when the difference between climb and takeoff fan
rotor speeds is no more than three percent. It would be overly
restrictive to limit the allowable variation to one percent when the
in-service difference between climb and takeoff fan rotor speeds, with
no change in throttle position, is typically in the range of three
percent to five percent. As a result, Sec. 33.76(e)(4) allows
applicants to combine the existing MFB and new climb flocking bird
tests if the engine's climb fan rotor speed is within three percent of
the fan rotor speed required in the MFB test under Sec. 33.76(c).
Combining the tests when the fan rotor speed is within 3 percent will
have no effect on the efficacy of the test because the bird for the
test at climb condition will be fired at the higher bird speed and a
fan rotor speed consistent with actual operations.
B. Consistent Usage of Bird Airspeed and Altitude Units (Sec.
33.76(e)(1)(i)(C) and (e)(2)(i)(C))
The NPRM proposed a bird speed of 250-knots for the new climb
flocking bird test and 200-knots for the new approach flocking bird
test. Honeywell International, The Boeing Company, AIA, Pratt &
Whitney, and GE stated that the NPRM used ``knots'' and ``knots
indicated airspeed'' (KIAS) inconsistently. Knots, KIAS, and knots true
airspeed (KTAS) can refer to different physical speeds. The commenters
also stated that the ARAC working group intended for the bird in the
climb flocking bird test to be fired at the equivalent of 250-KIAS at
an altitude of 3,000 feet MSL using ISA conditions, and 200-KIAS at an
altitude of 3,000 feet MSL using ISA conditions for the approach
flocking bird test. Therefore, to achieve consistency with the ARAC
working group recommendation, the commenters concluded the climb and
approach flocking bird tests should be performed with fan speeds
representative of the lowest possible fan rotor speed at these
conditions, and the bird velocities should be 261-KTAS for the climb
flocking bird test, and 209-KTAS for the approach flocking bird test.
KIAS measures airspeed modified to account for the altitude
pressure effect. KTAS is the speed of the aircraft relative to the air
mass through which it is flying. During a bird ingestion event, KTAS is
the effective speed of the bird relative to the aircraft. The NPRM did
not specify the altitude at which KIAS was based. For the climb
flocking bird test, 250-KIAS at 3,000 feet MSL equates to a bird speed
of 261-KTAS at sea level. For the approach flocking bird test, 200-KIAS
at 3,000 feet MSL equates to a bird speed of 209-KTAS at sea level. In
this final rule, the FAA has revised the proposed Sec.
33.76(e)(1)(i)(C) from ``Ingestion must be at 250-knots bird speed,''
to ``Ingestion must be at 261-knots true airspeed.'' The FAA also
revised the proposed Sec. 33.76(e)(2)(i)(C), from ``Ingestion must be
at 200-knots bird speed'' to ``Ingestion must be at 209-knots true
airspeed.''
In the NPRM, the agency proposed that the engine must be stabilized
during the test at the mechanical rotor speed of the first exposed fan
stage or stages that, on a standard day, produce the lowest expected
power or thrust required during climb through 3,000 feet AGL. MSL will
establish more consistent test conditions than AGL
[[Page 19805]]
because the flight conditions for the engine using AGL may vary based
upon the ground level altitude above sea level. For example, 3,000 feet
above Denver International Airport (5,434 feet above sea level) is
8,434 feet MSL; 3,000 feet above Boston Logan International Airport (19
feet above sea level) is 3,019 feet MSL. Using MSL defines the engine
conditions consistent with the commenters' request that the standard
refer to 3,000 feet at ISA conditions. The FAA has revised Sec.
33.76(e)(1)(i)(A) for the climb flocking bird test to require the fan
rotor speed to be set to the lowest expected power or thrust required
during climb through 3,000 feet MSL instead of 3,000 feet AGL.
The NPRM proposed in Sec. 33.76(e)(2)(i)(A) that the engine must
be stabilized during the test at the mechanical rotor speed of the
first exposed fan stage or stages when on a standard day the engine
thrust is set at approach idle thrust when descending 3,000 feet AGL.
The FAA also revised Sec. 33.76(e)(2)(i)(A) for the approach flocking
bird test to require the fan speed be set to the lowest expected power
or thrust required during descent through 3,000 feet MSL instead of
3,000 feet AGL, based on the same rationale as the climb flocking bird
test.
Finally, changing AGL to MSL will not result in different test
conditions than those proposed in the NPRM. For turbofan engines, power
or thrust is proportional to fan speed. The lowest fan speed for a
given climb thrust at standard day conditions and 3,000 feet AGL is
equivalent to 3,000 feet MSL. In addition, changing the altitude units
to MSL makes the altitude reference consistent with the requirement to
have the lowest fan speed at standard day conditions.
C. Removal of Reference to Approach Flocking Bird Test (Sec. Sec.
33.76(e)(4))
The NPRM preamble discussed the circumstances under which
applicants could combine the proposed climb flocking bird test with the
existing Sec. 33.76(c) test; however, the proposed regulatory text in
Sec. 33.76(e)(4)(ii) provided that the proposed approach flocking bird
test could also be combined with the Sec. 33.76(c) test. Honeywell
International and GE commented that proposed Sec. 33.76(e)(4)(ii)
should not be included in the final rule. Honeywell International
further explained that there is no scenario where the fan speed at the
approach condition will be within one percent, or even the recommended
three percent, of the max takeoff thrust fan speed. The FAA agrees that
applicants may only combine the climb flocking bird test with the Sec.
33.76(c) test since the conditions of the approach flocking bird test
are not consistent with the Sec. 33.76(c) test. Therefore, in this
final rule, Sec. 33.76(e)(4) does not include a reference to the
approach flocking bird test.
D. Proposal To Exclude Engine Inlets Greater Than 3.90 Square Meters
In the NPRM, the FAA proposed that either the climb or approach
flocking bird test would be required for all turbofan engines in
addition to the existing Sec. 33.76(c) test. GE commented that engines
with inlet areas of 3.90 square meters (6,045 square inches) or
greater, known as Class A size engines, should be excluded from the
requirement to perform the new test. Specifically, GE asserted that
engines should be excluded when the applicant can show that the
proposed type design for an engine has design features and functions
consistent with the applicant's successful MFB ingestion based on field
service experience and core ingestion compliance demonstrations with
previously certified engine types. GE reasoned that the ARAC report
shows that the data in the Aerospace Industries Association Bird
Ingestion Working Group Interim Report contained no reported loss of
power events associated with core bird ingestion into Class A size
turbofan engines between 1999 and 2009. GE also stated that its recent
compliance testing results provide clear evidence of core ingestion.
Therefore, compliance with the MFB ingestion requirements found in
Sec. 33.76(c) will present an appropriate and operationally relevant
MFB ingestion challenge for the largest size class of engines.
The FAA notes that between 2000 and 2009, there were between 12 and
20 million airplane flight cycles (a flight cycle includes a takeoff
and landing) per year with Class D size engines (1.35m\2\-2.5m\2\ inlet
areas, the same size as the engines on the US Airways Flight 1549
airplane). During that same time, there were less than 2 million
airplane flight cycles with Class A size engines per year. Along with
the low overall number of engine power loss events, this low number of
airplane flight cycles makes it difficult to statistically establish
that the prior service history of Class A size engines between 2000 and
2009 is sufficient to prove that the airplane is protected from hazards
due to engine core ingestion during climb, based on the engine inlet
area alone.
Additionally, the ARAC report did not make an exception for Class A
size engines or other engine sizes with relatively few core power loss
events. Instead, section 5 of the ARAC report indicates that the Sec.
33.76(c) core ingestion demonstration criteria did not adequately
represent the most critical flight phase with respect to core ingestion
due to the combination of high fan rotor speed and low aircraft speed.
The ARAC report discusses the effects of rotor speed and low aircraft
speed on core ingestion in paragraph 3.2.
With respect to GE's comment that signs of bird material are
consistently found on the spinner or in the core inlet area after the
Sec. 33.76(c) test and therefore are a reliable indicator of the core
flow path, the FAA does not concur. The ARAC report addressed this
topic in paragraph 4.3, Differentiating Between Core Induced Power Loss
vs. Material in the Core. The ARAC report stated:
It is believed that the presence of bird remains within the engine
core is not a reliable indicator of significant core ingestion because
bird strikes on aircraft structure other than the core intake area,
such as the inlet lip, spinner cap, and radome, regularly result in
some amount of avian material entering the core.\9\
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\9\ ARAC report at p. 25.
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Based on the information in the ARAC report, the FAA determined
that during a certification test, it is not possible to accurately
measure the amount of bird material that entered the core, as opposed
to bypassing the core. Testing the engine at the climb condition is the
best way to ensure significant bird material enters the core.
Therefore, consistent with the NPRM, this final rule does not except
Class A engines.
E. Using MFB Test To Meet Core Ingestion Requirement
The NPRM proposed that either the climb or approach flocking bird
test would be required for all turbofan engines in addition to the
existing Sec. 33.76(c) test, regardless of the results of the Sec.
33.76(c) test. GE commented that the approach flocking bird test
proposed in the NPRM should not be required if bird material entered
the core during the Sec. 33.76(e)(1) climb flocking bird test or the
Sec. 33.76(c) test, because ingestion of bird material during the
Sec. 33.76(c) test would demonstrate sufficient core robustness
against bird ingestion. In addition, GE commented that based on its
experience, the core capability could be demonstrated using the Sec.
33.76(c) test.
The ARAC found that bird velocity is predicted to have the greatest
influence on the amount of bird ingested into the
[[Page 19806]]
core for a given design.\10\ Also, generally, for a given bird
velocity, the amount of ingested bird material into the core is
inversely proportional to the fan rotor speed. Therefore, the new climb
flocking bird test in the new Sec. 33.76(e)(1) will provide a more
representative demonstration of core capability than the Sec. 33.76(c)
test due to the higher bird velocity and lower rotor fan speed required
by the climb flocking bird test.
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\10\ ARAC report at p. 17, 18.
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Additionally, the FAA proposed that the approach flocking bird test
would only be required if testing or validated analysis shows that no
bird material will be ingested into the engine core during the Sec.
33.76(e)(1) climb flocking bird test. As stated in the NPRM, testing at
the 200-KIAS (209-KTAS) approach condition would ensure that, if the
engine is designed to centrifuge all bird material away from the core
flow path at takeoff and climb conditions (which is beneficial), then
engine core capability to ingest bird material would still be tested.
This is because an engine that centrifuges bird material away from the
core at the 250-KIAS (261-KTAS) climb condition may not be able to
centrifuge away the same amount of bird material at the lower speed
approach condition. The NPRM stated that the approach flocking bird
test would only be required if testing or validated analysis shows that
no bird material will be ingested into the engine core during the Sec.
33.76(e)(1) climb flocking bird test. Consequently, the FAA did not
change the rule as a result of comments seeking to exclude the approach
flocking bird test if material entered the core during the Sec.
33.76(c) test.
F. Approach Flocking Bird Test Run-On Requirement Wording
In the NPRM, the FAA proposed post-test bird ingestion run-on
requirements for the new climb and approach flocking bird tests. Rolls-
Royce, Honeywell International, The Boeing Company, AIA, Pratt &
Whitney, and GE suggested the NPRM preamble description of the engine
run-on requirements for the approach flocking bird test was confusing.
The NPRM preamble stated that applicants would be required to comply
with the same post-test run-on requirements as those for the final six
minutes of the existing Sec. 33.76(d)(5) post-test run-on requirements
for LFB. The NPRM preamble also stated that the post-test run-on
requirements for the proposed approach flocking bird test would consist
of the final seven minutes of the existing LFB 20-minute post-ingestion
run-on requirement.
The FAA clarifies that the phrase ``final seven minutes'' in the
NPRM preamble included a 1-minute period after ingestion when the
engine throttle must not be manipulated, followed by the final six
minutes of the LFB run-on requirement. Consistent with the preamble
discussion, the proposed regulatory text in Sec. 33.76(e)(2)(iii)
included a total of both the 1-minute delay after ingestion and the
final six minutes of the LFB run-on. Therefore, in this final rule, the
FAA adopts Sec. 33.76(e)(2)(iii) as proposed.
G. MFB Bird Speed (Sec. 33.76(c))
Honeywell International, The Boeing Company, AIA, Pratt & Whitney,
and GE commented that the NPRM preamble improperly described the Sec.
33.76(c) bird speed requirement. The NPRM preamble stated that the MFB
test is conducted using 100 percent power or thrust and 200-knots
airspeed, simulating takeoff conditions. However, Sec. 33.76(c) states
that the critical bird ingestion speed should reflect the most critical
condition within the range of airspeeds used for normal flight
operations up to 1,500 feet AGL, but not less than V1
minimum for airplanes. Therefore, while the NPRM preamble's description
of the Sec. 33.76(c) bird speed requirement was inaccurate, the
proposed regulatory text was correct.
H. Number of Required Tests
The NPRM preamble stated that it was unlikely that manufacturers
would need to run multiple tests to meet the proposed test
requirements. GE questioned the accuracy of this assertion, requesting
that the FAA acknowledge the possibility that the proposal could result
in two additional ingestion tests.
The FAA has determined that manufacturers are unlikely to have to
run two additional tests because the agency expects that manufacturers
will evaluate the design of their engines before testing and should be
able to determine whether engines will centrifuge all bird material
away from the engine core. In this final rule, a manufacturer may
perform either the climb or approach test; however, they would perform
the approach test only if testing or a validated analysis shows that no
bird material will enter the engine core. By performing a validated
analysis to determine whether an engine will centrifuge all bird
material away from the engine core during the climb flocking bird test,
a manufacturer will be able to know ahead of time whether to run either
the climb or the approach flocking bird test.\11\ Therefore, while it
is possible that the final rule could result in two additional
ingestion tests, it remains unlikely.
---------------------------------------------------------------------------
\11\ Advisory Circular 33.76-1B, published with this final rule,
provides guidance for using a validated core ingestion prediction
analysis.
---------------------------------------------------------------------------
The FAA notes that the ARAC report found that various engine
manufacturer simulation results have shown that, in general for a given
bird velocity, the amount of ingested bird material into the core is
inversely proportional to the fan rotor speed.\12\ During the ARAC
working group study, at least three different engine manufacturers who
had conducted these simulations presented engineering analyses
predicting how much bird material would enter the core after ingestion
(See Figure 3.2.2 of the ARAC report). This indicated that industry has
the capability to determine before the test, whether engines will
centrifuge all bird material away from the engine core.
---------------------------------------------------------------------------
\12\ ARAC report at p. 17, 18.
---------------------------------------------------------------------------
I. Canada Geese
As noted by Honeywell International, AIA, and Pratt & Whitney, the
NPRM incorrectly referred to the birds ingested into the engines of
Flight 1549 as ``Canadian geese'' rather than ``Canada geese.'' The
preamble to this final rule uses the term ``Canada geese,'' reflecting
the proper bird identification.\13\
---------------------------------------------------------------------------
\13\ NTSB report AAR-10/03 at section 1.18.1.2, ``Canada Goose
Information.''
---------------------------------------------------------------------------
J. Regulatory Evaluation Costs
The NPRM summarized the results of the FAA evaluation of the costs
and benefits associated with the proposal. GE disagreed with the total
benefits and costs of the proposed rule as described in the NPRM. The
commenter expressed that the cost and benefit analyses do not include
the additional incremental cost to develop and mature the technology to
pass the additional certification test(s) and to conduct and pass the
additional certification test(s).
The commenter's costs discussion shows that it is possible that the
cost to design and develop engine blades and vanes to comply with the
new rule could be significantly different from those estimated in the
preliminary regulatory impact analysis. While the new test is intended
to increase the amount of bird material entering the engine core
relative to the existing Sec. 33.76(c) test, the fundamental
requirement for blades and vanes behind the fan to withstand foreign
object damage from bird ingestion has not changed. Since Sec. 33.76 at
Amendment 20 (65 FR 55848, September 14, 2000), applicants have
[[Page 19807]]
been required to aim the largest MFB at the engine core primary flow
path. In addition, other regulations (such as Sec. 33.78(a)(1) for
hailstone ingestion) have also required applicants to account for
potential impact damage when designing their core engine blades and
vanes. The need for new engineering analysis, development tools, and
methods when developing a new blade to meet this final rule's new test
requirement will vary among manufacturers depending on the physical
design of their engines, their development philosophy, and their
tolerance for risk during the certification process. For example, an
engine manufacturer who designs its engine so no material would enter
the engine core during either the climb or approach condition could
have zero developmental costs due to the new regulation. Others might
desire or require additional developmental work to ensure a future
engine would meet the new requirement. The FAA has revised the
regulatory analysis to address the potential for pre-certification
developmental costs.
GE also criticized the analysis as significantly underestimating
production costs. The commenter stated that, for example, a production
rate of nearly 3,000 engines per year should be used instead of the FAA
estimate of 220 engines per year. The FAA contacted the commenter to
clarify whether its comment was based on the belief that the FAA was
estimating 220 affected engines would be produced per year in total.
The FAA asked if the commenter believed that instead, the total number
of engines produced by all engine manufacturers in one year should be
closer to 3,000. The commenter responded that it thought the 220
engines produced per year were for all manufacturers. The commenter
mentioned the CFM International LEAP engine production rate is nearly
3,000 engines per year as an example. Therefore, the commenter believes
the total of 220 engines given in the benefits and costs analysis of
the NPRM is too low.
The FAA clarifies that the 220 engines in its economic analysis are
per new engine certification (i.e., one certification for each
manufacturer). More specifically, in the regulatory evaluation, the FAA
estimated that three engines would be certified every year and two
additional engines would be certified every three years. Additionally,
the FAA assumed production of the engines would begin one year after
certification. Finally, the FAA estimated that, on average, 220 engines
would be produced per year, per certification. To calculate engines in-
service that would be affected by this final rule, the FAA assumes the
estimated average service life of an engine is about 16 years.
Therefore, in the first year of compliance, the FAA estimated five
engines would be certified with 1,100 engines produced. In the second
year, three more engines are certified, and in the following year, an
additional 660 engines would be produced. In the third year, another
three certifications occur with an additional 660 engines produced. In
the fourth year, five engines would be certified with another 1,100
engines produced. After 10 years, the engines produced from the tenth
year would be installed the following year and continue in-service for
16 years. The number of affected engines reach a maximum in the twelfth
year and, with no attrition, there are 8,360 engines in-service until
year 18 when the engines in operation begin to retire. After 27 years,
all the affected engines would be retired. See ``Table 1. Engine
Certifications and Aircraft in Service Forecast'' of the Regulatory
Evaluation for details.
The FAA's estimate of 220 engines produced per year, per
certification, is based on the average production rate per year, from
1989 to 2015, for the V2500 engine. The V2500 engine is installed on
the Airbus A320 airplane and the MD-80 airplane. Larger engines like
the GE90 (installed on the Boeing 777) would be produced at a lower
average rate and smaller engines like the CF34 (regional jet) would be
produced at a higher average rate.
The FAA compared the estimate of 220 engines per year against the
data for engines previously certified to determine if the 220 estimate
is too low. This rule only affects engines with a certification date of
application after the effective date of the final rule and does not
affect the CFM International LEAP engine. The data shows that the
average production rate per year from 2008 to 2017 for the V2500 engine
is 182 engines per year. Furthermore, the average production of
certified engines from 2008 to 2017 is even less (108 engines per
year). For this reason, the FAA's use of 220 engines per certification
to estimate the operating cost of this rule is justified.
K. Miscellaneous Changes Between the NPRM and the Final Rule
In the NPRM, proposed Sec. 33.76(e)(1)(iii)(D) included the
allowance that ``Power lever movement in this condition is unlimited''
for that segment of the climb flocking bird test. The FAA inadvertently
omitted a similar allowance in proposed Sec. 33.76(e)(2). To correct
this omission and make the approach flocking bird test schedule
consistent with the climb flocking bird test schedule, the FAA added
``Power lever movement in this condition is unlimited'' to the end of
Sec. 33.76(e)(2)(iii)(C) in this final rule.
The FAA modified the proposed test requirements in paragraphs
(e)(1)(i)(B) and (e)(2)(i)(B) to Sec. 33.76, to clarify that only one
bird is required for the climb flocking bird test and approach flocking
bird test added by this final rule.
Section 33.76(a)(5) allows applicants to substitute objects that
are accepted by the Administrator for birds when conducting the
existing bird ingestion tests. The FAA amended Sec. 33.76(a)(5) by
adding a reference to new Sec. 33.76(e) for consistency with the
allowance for other bird ingestion tests.
In order to be consistent with the existing wording in Sec.
33.76(b) through (d), the FAA does not use the word ``fan'' in this
final rule when describing the first exposed rotor stage in Sec.
33.76(e)(1)(i)(A) and (D), (e)(2)(i)(A) and (D), and (e)(4).
IV. Regulatory Notices and Analyses
A. Regulatory Evaluation
Changes to Federal regulations must undergo several economic
analyses. First, Executive Order 12866 and Executive Order 13563 direct
that each Federal agency shall propose or adopt a regulation only upon
a reasoned determination that the benefits of the intended regulation
justify its costs. Second, the Regulatory Flexibility Act of 1980 (Pub.
L. 96-354) requires agencies to analyze the economic impact of
regulatory changes on small entities. Third, the Trade Agreements Act
(Pub. L. 96-39) prohibits agencies from setting standards that create
unnecessary obstacles to the foreign commerce of the United States. In
developing U.S. standards, the Trade Agreements Act requires agencies
to consider international standards and, where appropriate, that they
be the basis of U.S. standards. Fourth, the Unfunded Mandates Reform
Act of 1995 (Pub. L. 104-4) requires agencies to prepare a written
assessment of the costs, benefits, and other effects of proposed or
final rules, that include a Federal mandate likely to result in the
expenditure by State, local, or tribal governments, in the aggregate,
or by the private sector, of $100 million or more annually (adjusted
for inflation with base year of 1995; current value is $155 million).
This portion of the preamble summarizes the FAA's analysis of the
economic impacts of this final rule. The FAA suggests readers seeking
greater detail read the
[[Page 19808]]
full regulatory evaluation, a copy of which is available 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 not ``significant'' as defined in
DOT's Regulatory Policies and Procedures; (4) will not have a
significant economic impact on 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 FAA is amending certain airworthiness regulations to add a new
test requirement to the airworthiness regulation addressing engine bird
ingestion. This final rule ensures that engines can ingest the largest
MFB into the engine core at climb or approach conditions. The ingestion
of MFB can cause thrust loss from core engine bird ingestion if enough
bird mass enters the engine core, which in turn can cause an accident
or flight diversion. This rule adds to the certification requirements
of turbofan engines, a requirement that manufacturers must show that
their engine cores can continue to operate after ingesting an MFB while
operating at a lower fan speed associated with climb or approach.
Engine manufacturers have the capability of producing such engines.
The FAA estimates the annualized cost of the rule to be $5.3
million, or present value $64.0 million over 27 years (discounted at 7
percent).\14\ The FAA estimates the annualized benefits of the rule to
be $6.1 million, or present value $73.7 million over 27 years
(discounted at 7 percent). The following table summarizes the benefits
and costs of this final rule. The FAA has revised the analysis of costs
for the final rule based on information received during the public
comment period (for details see section J. Regulatory Evaluation
Costs).
---------------------------------------------------------------------------
\14\ The FAA uses a 27-year period of analysis since it
represents one complete cycle of actions affected by the rule. One
life cycle extends through the time required for certification,
production of the engines, engine installation, active engine
service, and retirement of the engines.
Summary of Benefits and Costs
[$Millions]
----------------------------------------------------------------------------------------------------------------
27-Year total 27-Year total
present value present value Annualized 7% Annualized 3%
Impact 7% present 3% present present value present value
value value
----------------------------------------------------------------------------------------------------------------
Benefits........................................ $73.7 $121.6 $6.1 $6.6
Costs........................................... 64.0 85.4 5.3 4.7
Net Benefits................................ 9.7 36.2 0.8 1.9
----------------------------------------------------------------------------------------------------------------
1. This rule addresses two engine-related safety recommendations that
the NTSB issued to the FAA: (1) A-10-64 and (2) A-10-65.
2. Who is potentially affected by this rule?
Aircraft operators and engine manufacturers.
3. Assumptions
The benefit and cost analysis for the regulatory evaluation is
based on the following assumptions:
The analysis is conducted in constant dollars with 2020 as
the base year.
The FAA calculated the present value of the potential
benefits by discounting the monetary values following the Office of
Management and Budget guidance using a 7 percent and a 3 percent
interest rate.
The analysis period is 27 years with 10 years of new
engine certifications.
Based on the actual production numbers of a common airline
engine, the FAA estimates that about 220 engines are produced per year
per certification.
Because of this final rule, the average fuel consumption
will increase by $821 per year per aircraft.
B. Regulatory Flexibility Determination
The Regulatory Flexibility Act of 1980 (RFA) establishes ``as a
principle of regulatory issuance that agencies shall endeavor,
consistent with the objective of the rule and of applicable statutes,
to fit regulatory and informational requirements to the scale of the
business, organizations, and governmental jurisdictions subject to
regulation.'' To achieve that principle, the RFA requires agencies to
solicit and consider flexible regulatory proposals and to explain the
rationale for their actions. The RFA covers a wide-range of small
entities, including small businesses, not-for-profit organizations, and
small governmental jurisdictions.
Agencies must perform a review to determine whether a proposed or
final rule will have a significant economic impact on a substantial
number of small entities. If the agency determines that it will, the
agency must prepare a regulatory flexibility analysis as described in
the Act.
Two groups will be affected by this rule: aircraft operators and
engine manufacturers.
The FAA has determined that this final rule will not have a
significant economic impact on small aircraft operators. Operators will
incur higher fuel burn costs due to an increase in engine weight
(heavier blading, components, etc.), and consequently, an increase in
total aircraft weight. The FAA estimates fuel burn costs of $750 per
year per aircraft, which the FAA has determined will not result in a
significant economic impact for small aircraft operators.
Similarly, the FAA has determined that this final rule will not
have a significant economic impact on engine manufacturers. The FAA
identified one out of five engine manufacturers that meet the Small
Business Administration definition of a small entity. The annual
revenue estimate for this manufacturer is about $75 million.\15\ The
FAA then compared this manufacturer's revenue with its annualized
compliance cost. The FAA expects that the manufacturer's projected
annualized cost would be 0.3 percent of its annual revenue,\16\ which
the FAA has
[[Page 19809]]
determined is not a significant economic impact.
---------------------------------------------------------------------------
\15\ Source: http://www.manta.com.
\16\ Ratio = annualized cost/annual revenue = $220,355/
$74,800,000 = 0.3%.
---------------------------------------------------------------------------
If an agency determines that a rulemaking will not result in a
significant economic impact on a substantial number of small entities,
the head of the agency may so certify under section 605(b) of the RFA.
Therefore, as provided in section 605(b), the head of the FAA certifies
that this rulemaking will not result in a significant economic impact
on a substantial number of small entities.
C. 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 it
has legitimate domestic safety objectives. Therefore, this final rule
is in compliance with the Trade Agreements Act.
D. 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 $155 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.
E. 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.
F. 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
determined that there are no ICAO Standards and Recommended Practices
that correspond to these regulations.
G. Environmental Analysis
FAA Order 1050.1F 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 5-6.6 and involves no extraordinary
circumstances.
H. Regulations Affecting Intrastate Aviation in Alaska
Section 1205 of the FAA Reauthorization Act of 1996 (110 Stat.
3213) requires the Administrator, when modifying 14 CFR 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. The FAA
has determined that this rule would not affect intrastate aviation in
Alaska.
V. Executive Order Determinations
A. Executive Order 13132, Federalism
The FAA has analyzed this final rule under the principles and
criteria of Executive Order 13132, Federalism. The agency 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, and, therefore, does not have federalism
implications.
B. Executive Order 13211, 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). The agency has determined that it
is not a ``significant energy action'' under the Executive order and it
is not likely to have a significant adverse effect on the supply,
distribution, or use of energy.
C. Executive Order 13609, International Cooperation
Executive Order 13609, Promoting International Regulatory
Cooperation, (77 FR 26413, May 4, 2012) promotes international
regulatory cooperation to meet shared challenges involving health,
safety, labor, security, environmental, and other issues and reduce,
eliminate, or prevent unnecessary differences in regulatory
requirements. The FAA has analyzed this action under the policy and
agency responsibilities of Executive Order 13609, Promoting
International Regulatory Cooperation. The agency has determined that
this action will eliminate differences between U.S. aviation standards
and those of other civil aviation authorities by ensuring that Sec.
33.76 remains harmonized with European Union Aviation Safety Agency
Certification Specification CS-E 800.
VI. How To Obtain Additional Information
A. Rulemaking Documents
An electronic copy of a rulemaking document may be obtained by
using the internet--
1. Search the Federal eRulemaking Portal (www.regulations.gov);
2. Visit the FAA's Regulations and Policies web page at
www.faa.gov/regulations_policies/; or
3. Access the Government Printing Office's web page at
www.GovInfo.gov.
Copies may also be obtained by sending a request (identified by
notice, amendment, or docket number of this rulemaking) to the Federal
Aviation Administration, Office of Rulemaking, ARM-1, 800 Independence
Avenue SW, Washington, DC 20591, or by calling (202) 267-9680.
B. 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. A small entity with questions regarding this document,
may contact its local FAA official, or the person listed under the FOR
FURTHER INFORMATION CONTACT heading at the beginning of the preamble.
To find out more about SBREFA on the internet, visit www.faa.gov/regulations_policies/rulemaking/sbre_act/.
[[Page 19810]]
List of Subjects in 14 CFR Part 33
Bird ingestion.
The Amendment
In consideration of the foregoing, the Federal Aviation
Administration amends chapter I of title 14, Code of Federal
Regulations as follows:
PART 33--AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES
0
1. The authority citation for part 33 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.
0
2. Amend Sec. 33.76 by revising the introductory text to paragraph (a)
and paragraphs (a)(1) and (5) and adding paragraph (e) to read as
follows:
Sec. 33.76 Bird ingestion.
(a) General. Compliance with paragraphs (b) through (e) of this
section shall be in accordance with the following:
(1) Except as specified in paragraphs (d) and (e) of this section,
all ingestion tests must be conducted with the engine stabilized at no
less than 100 percent takeoff power or thrust, for test day ambient
conditions prior to the ingestion. In addition, the demonstration of
compliance must account for engine operation at sea level takeoff
conditions on the hottest day that a minimum engine can achieve maximum
rated takeoff thrust or power.
* * * * *
(5) Objects that are accepted by the Administrator may be
substituted for birds when conducting the bird ingestion tests required
by paragraphs (b) through (e) of this section.
* * * * *
(e) Core flocking bird test. Except as provided in paragraph (e)(4)
of this section, for turbofan engines, an engine test must be performed
in accordance with either paragraph (e)(1) or (2) of this section. The
test specified in paragraph (e)(2) must be conducted if testing or
validated analysis shows that no bird material will be ingested into
the engine core during the test under the conditions specified in
paragraph (e)(1).
(1) Climb flocking bird test. (i) Test requirements are as follows:
(A) Before ingestion, the engine must be stabilized at the
mechanical rotor speed of the first exposed stage or stages that
produce the lowest expected power or thrust required during climb
through 3,000 feet above mean sea level (MSL) at standard day
conditions.
(B) The climb flocking bird test shall be conducted using one bird
of the highest weight specified in table 2 to this section for the
engine inlet area.
(C) Ingestion must be at 261-knots true airspeed.
(D) The bird must be aimed at the first exposed rotating stage or
stages, at the blade airfoil height, as measured at the leading edge
that will result in maximum bird material ingestion into the engine
core.
(ii) Ingestion of a flocking bird into the engine core under the
conditions prescribed in paragraph (e)(1)(i) of this section must not
cause any of the following:
(A) Sustained power or thrust reduction to less than 50 percent
maximum rated takeoff power or thrust during the run-on segment
specified under paragraph (e)(1)(iii)(B) of this section, that cannot
be restored only by movement of the power lever.
(B) Sustained power or thrust reduction to less than flight idle
power or thrust during the run-on segment specified under paragraph
(e)(1)(iii)(B) of this section.
(C) Engine shutdown during the required run-on demonstration
specified in paragraph (e)(1)(iii) of this section.
(D) Any condition specified in Sec. 33.75(g)(2).
(iii) The following test schedule must be used (power lever
movement between conditions must occur within 10 seconds or less,
unless otherwise noted):
Note 1 to paragraph (e)(1)(iii) introductory text. Durations
specified are times at the defined conditions in paragraphs
(e)(1)(iii)(A) through (I) of this section.
(A) Ingestion.
(B) Followed by 1 minute without power lever movement.
(C) Followed by power lever movement to increase power or thrust to
not less than 50 percent maximum rated takeoff power or thrust, if the
initial bird ingestion resulted in a reduction in power or thrust below
that level.
(D) Followed by 13 minutes at not less than 50 percent maximum
rated takeoff power or thrust. Power lever movement in this condition
is unlimited.
(E) Followed by 2 minutes at 30-35 percent maximum rated takeoff
power or thrust.
(F) Followed by 1 minute with power or thrust increased from that
set in paragraph (e)(1)(iii)(E) of this section, by 5-10 percent
maximum rated takeoff power or thrust.
(G) Followed by 2 minutes with power or thrust reduced from that
set in paragraph (e)(1)(iii)(F) of this section, by 5-10 percent
maximum rated takeoff power or thrust.
(H) Followed by 1 minute minimum at ground idle.
(I) Followed by engine shutdown.
(2) Approach flocking bird test. (i) Test requirements are as
follows:
(A) Before ingestion, the engine must be stabilized at the
mechanical rotor speed of the first exposed stage or stages that
produce approach idle thrust when descending through 3,000 feet MSL at
standard day conditions.
(B) The approach flocking bird test shall be conducted using one
bird of the highest weight specified in table 2 to this section for the
engine inlet area.
(C) Ingestion must be at 209-knots true airspeed.
(D) The bird must be aimed at the first exposed rotating stage or
stages, at the blade airfoil height measured at the leading edge that
will result in maximum bird material ingestion into the engine core.
(ii) Ingestion of a flocking bird into the engine core under the
conditions prescribed in paragraph (e)(2)(i) of this section may not
cause any of the following:
(A) Power or thrust reduction to less than flight idle power or
thrust during the run-on segment specified under paragraph
(e)(2)(iii)(B) of this section.
(B) Engine shutdown during the required run-on demonstration
specified in paragraph (e)(2)(iii) of this section.
(C) Any condition specified in Sec. 33.75(g)(2).
(iii) The following test schedule must be used (power lever
movement between conditions must occur within 10 seconds or less,
unless otherwise noted):
Note 2 to paragraph (e)(2)(iii) introductory text. Durations
specified are times at the defined conditions in paragraphs
(e)(2)(iii)(A) through (H) of this section.
(A) Ingestion.
(B) Followed by 1 minute without power lever movement.
(C) Followed by 2 minutes at 30-35 percent maximum rated takeoff
power or thrust. Power lever movement in this condition is unlimited.
(D) Followed by 1 minute with power or thrust increased from that
set in paragraph (e)(2)(iii)(C) of this section, by 5-10 percent
maximum rated takeoff power or thrust.
(E) Followed by 2 minutes with power or thrust reduced from that
set in paragraph (e)(2)(iii)(D) of this section, by 5-10 percent
maximum rated takeoff power or thrust.
(F) Followed by 1 minute minimum at ground idle.
(G) Followed by engine shutdown.
(H) Power lever movement between each condition must be 10 seconds
or less, except that any power lever movements are allowed within the
time
[[Page 19811]]
period of paragraph (e)(2)(iii)(C) of this section.
(3) Results of exceeding engine-operating limits. Applicants must
show that an unsafe condition will not result if any engine-operating
limit is exceeded during the run-on period.
(4) Combining tests. The climb flocking bird test of paragraph
(e)(1) of this section may be combined with the medium flocking bird
test of paragraph (c) of this section, if the climb first stage rotor
speed calculated in paragraph (e)(1) of this section is within 3
percent of the first stage rotor speed required by paragraph (c)(1) of
this section. As used in this paragraph (e)(4), ``combined'' means
that, instead of separately conducting the tests specified in
paragraphs (c) and (e)(1) of this section, the test conducted under
paragraph (c) of this section satisfies the requirements of paragraph
(e) of this section if the bird aimed at the core of the engine meets
the bird ingestion speed criteria of paragraph (e)(1)(i)(C) of this
section.
Issued under authority provided by 49 U.S.C. 106(f), 44701(a),
and 44704 in Washington, DC, on or about March 23, 2023.
Billy Nolen,
Acting Administrator.
[FR Doc. 2023-06413 Filed 4-3-23; 8:45 am]
BILLING CODE 4910-13-P