[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
                                                 ---------------------------------------------------------------
    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


