[Federal Register Volume 65, Number 179 (Thursday, September 14, 2000)]
[Rules and Regulations]
[Pages 55848-55856]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-23175]



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Part V





Department of Transportation





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Federal Aviation Administration



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14 CFR Parts 23, 25, and 33



Airworthiness Standards; Bird Ingestion; Final Rule

  Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 / 
Rules and Regulations  

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Parts 23, 25, 33

[Docket No. FAA-1998-4815; Amendment No. 23-54, 25-100 and 33-20]
RIN 2120-AF84


Airworthiness Standards; Bird Ingestion

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: This amendment revises the bird ingestion type certification 
standards for aircraft turbine engines to better address the actual 
bird threat encountered in service. This amendment also establishes 
nearly uniform bird ingestion standards for aircraft turbine engines 
certified by the United States under FAA standards and by the Joint 
Aviation Authorities (JAA) countries under JAA standards, thereby 
simplifying airworthiness approvals for import and export.

Effective Dates: December 13, 2000.

FOR FURTHER INFORMATION CONTACT: Marc Bouthillier, Engine and Propeller 
Directorate, Engine and Propeller Standards Staff, ANE-110, Federal 
Aviation Administration, New England Executive Park, Burlington, 
Massachusetts 01803-5299; telephone (781) 238-7120; facsimile (781) 
238-7199.

SUPPLEMENTARY INFORMATION:

Availability of Final Rules

    An electronic copy of this document may be downloaded using a modem 
and suitable communications software from the FAA regulations section 
of the FedWorld Electronic bulletin board service (telephone: (703) 
321-3339) or the Government Printing Office's (GPO) electronic bulletin 
board service (telephone: (202) 512-1661).
    Internet users may reach the FAA's web page at http://www.faa.gov/avr/arm/nprm/nprm.htm or the GPO's web page at http://www.access.gpo.gov/nara for access to recently published rulemaking 
documents.
    Any person may obtain a copy of this document by submitting a 
request to the Federal Aviation Administration, Office of Rulemaking, 
ARM-1, 800 Independence Avenue SW., Washington, DC 20591, or by calling 
(202) 267-9680. Communications must identify the amendment number or 
docket number of this final rule.
    Persons interested in being placed on the mailing list for future 
rulemaking documents should request from the above office a copy of 
Advisory Circular No. 11-2A, Notice of Proposed Rulemaking Distribution 
System, which describes the application procedure.

Small Business Regulatory Enforcement Fairness Act

    The Small Business Regulatory Enforcement Fairness Act (SBREFA) of 
1996, requires the FAA to comply with small entity requests for 
information or advice about compliance with statutes and regulations 
within its jurisdiction. Therefore, any small entity that has a 
question regarding this document may contact their local FAA official. 
Internet users can find additional information on SBREFA on the FAA's 
web page at http://www.faa.gov/avr/arm/sbrefa.htm and may send 
electronic inquiries to the following Internet address: [email protected].

Background

Statement of the Problem

    In 1976, the National Transportation Safety Board (NTSB), in 
response to an accident involving a wide-bodied aircraft that may have 
experienced multiple bird ingestion into the engines, issued Safety 
Recommendation A-76-64, recommending that the FAA, ``amend 14 CFR 33.77 
to increase the maximum number of birds in the various size categories 
required to be ingested into turbine engines with large inlets.'' 
Safety Recommendation A-76-64 also stated, ``these increased numbers 
and sizes should be consistent with the birds ingested during service 
experience of these engines.'' In response to the recommendation, the 
FAA sponsored an industry wide study of the types, sizes, and 
quantities of birds that had been ingested into aircraft turbine 
engines of all sizes, and the resulting affects on engine performance. 
Subsequently, the FAA requested that the Aerospace Industries 
Association (AIA) analyze the data, and report back to the FAA. Based 
on the AIA report, the FAA determined the actions to be taken, as well 
as the disposition of the NTSB safety recommendation A-76-64. The FAA 
concluded that the regulations contained in Sec. 33.77 should be 
modified to increase the severity of the bird ingestion testing 
requirements regarding large, high bypass ratio engines. In addition, 
the FAA found that it should update the design and testing requirements 
for all engine sizes to reflect the actual numbers and bird sizes being 
ingested. This effort was adopted as a part 33 and Joint Aviation 
Regulations for engines (JAR-E) harmonization project and was selected 
as an Aviation Rulemaking Advisory Committee (ARAC) project.

Industry Study

    There are three separate data collection efforts within the 
industry study. The largest and most comprehensive collection is the 
data for large commercial transport engines with fan diameters between 
80 and 100 inches and spanning a time period from entry into service 
through 1987. This collection includes FAA sponsored contracts which 
are summarized in report number DOT/FAA/CT-84/13, dated September 1984. 
A less extensive collection effort involving engines with inlet areas 
less than 1000 square inches was also performed. Data for this class of 
engine is less comprehensive in that it involves reporting from a very 
diverse aircraft operator base including General Aviation operators as 
well as some commuter and part 121 operators. The third collection 
effort was an extension of the first, but includes only data for 
ingestion of birds weighing greater than 2.5 pounds, for the time 
period from entry into service through September 1995 for large 
commercial transport engines with fan diameters 60 inches and larger.
    The results of the first two data collections were compared to the 
historical design standards and certification bases for the family of 
engines comprised in the database. The study group identified bird 
ingestion threats both more and less severe than were addressed in 
either engine design practices of the time, or in part 33. A proposal 
for a change in the medium bird ingestion rules was presented by the 
AIA to the FAA in AIA report dated October 17, 1986.
    The FAA then asked for expansion of the database to include both 
heavier birds and coordination of the data and proposed rules with the 
European Association of Aerospace Industries (AECMA). This coordination 
effort included consensus between the two industry groups on the 
completeness and accuracy of the data, and validation of the analytical 
approach by independent statisticians from Allied Signal, Boeing, 
General Electric, Pratt & Whitney, Rolls-Royce, and Snecma. The AIA and 
AECMA delivered a report to the FAA on November 10, 1988. This data 
collection has become known as the ``AIA database.'' The substance of 
the latter report is a primary basis for the current NPRM.
    Three additional bird ingestion studies were contracted by the FAA 
to corroborate the findings of the collections described above. The 
results of these studies may be found in reports

[[Page 55849]]

numbered DOT/FAA/CT-90/13, ``Study of Bird Ingestions Into Small Inlet 
Area Aircraft Turbine Engines,'' dated December 1990, DOT/FAA/CT-91/17, 
``Bird Ingestion Into Large Turbofan Engines,'' dated May 1992, and 
DOT/FAA/CT-91/32, ``Engine Bird Ingestion Experience of the Boeing 737 
Aircraft--Expanded Data Base'', dated July 1992. The data contained in 
these reports supports the data summaries of the related industry 
studies.
    Subsequently, a further review of the data for birds heavier than 
2.5 pounds (lb) was requested of industry by the FAA and JAA. The 
resulting data is contained in an AIA/AECMA report dated March 29, 1996 
which includes all relevant reports of bird ingestions for commercial 
transport engines with fan diameters 60 inches and greater, for the 
time period from entry into service through September 30, 1995.

Aviation Rulemaking Advisory (ARAC) Project

    In December 1992, the FAA requested the ARAC to evaluate the need 
for new bird ingestion standards. The task, in turn, was assigned to 
the Engine Harmonization Working Group (EHWG) of the ARAC on Transport 
Airplane and Engine (TAE) Issues on December 11, 1992. On April 9, 
1997, the TAE issues group recommended to the FAA that it proceed with 
rulemaking and associated advisory material even though one working 
group member disagreed with a portion of the proposal. The FAA 
published a notice of proposed rulemaking (NPRM) on December 11, 1998 
(63 FR 68636). This rule reflects the ARAC recommendations.

Discussion of Comments

    All interested persons have been afforded an opportunity to 
participate in this rulemaking. Due consideration has been given to all 
comments contained in the nine comment letters received, which 
represent domestic and foreign industry, and foreign airworthiness 
authorities. Nine comments generally supported publication of the rule 
as a benefit over the existing regulations.
    One commenter notes that the companion Advisory Circular (AC) has 
not been published for comment.
    The FAA agrees in part. An extensive AC has been drafted that 
provides one method, but not the only method, for showing compliance 
with this new rule for bird ingestion. The FAA expects that the AC will 
be available for comment prior to the effective date of the new rule. 
The FAA does not agree that this final rule should be delayed pending 
completion of that AC.
    Two commenters state that the safety intent and justification of 
the proposed rule should be clarified.
    The FAA disagrees. The NPRM preamble clearly states that the 
objective of the proposed rule is to provide a freedom from risk of 
hazard due to bird ingestion at least equal to ten to the minus eighth 
power (1E-8) per aircraft cycle. The objective is further defined for 
single large birds and both small and medium flocking birds. 
Justification for various aspects of the rule is given throughout the 
preamble section of the NPRM.
    Several comments were received concerning bird control programs at 
airports. One commenter states that additional actions are necessary to 
better control bird populations on and around airports. Two commenters 
state that airport bird control programs and flight crew awareness 
training are not effective in mitigating the bird threat, and should 
not be considered relative to this rulemaking. One commenter states 
that airport bird control programs and flight crew awareness training 
programs are generally being decreased in scope.
    The FAA disagrees that airport controls programs and flight crew 
awareness training are ineffective in mitigating the bird ingestion 
threat. The FAA believes airport bird control programs are effective in 
mitigating the bird ingestion threat on and around airports. It must be 
noted that the overall bird ingestion experience base of commercial 
aircraft is a combination of aircraft capability, airport and environ 
controls, air traffic control, and flight crew awareness. Only by a 
combination of efforts will the bird ingestion threat to aircraft be 
kept to acceptable levels. It should be noted that the proposal did not 
specifically consider airport controls, air traffic controls, or flight 
crew effects in the design of the rule, other than assuming current 
levels of effectiveness will be maintained. Also, airport wildlife 
controls themselves are beyond the scope of this rulemaking effort.
    It should also be noted that the FAA has recently published a 
number of policy and guidance related documents pertaining to airport 
wildlife control plans, land use practices, and aircraft bird strike 
reporting. The FAA also participates in various government and industry 
focus groups related to wildlife hazards on and around airports, 
maintains a bird strike database, and has contracted with the 
Smithsonian institution to provide a service to identify and size birds 
involved in aircraft strike events. As a result of these efforts, the 
emphasis on wildlife hazard identification and control measures is 
expanding industry wide.
    One commenter states that fan blade containment after a bird 
ingestion event is a concern.
    The FAA agrees in part. The FAA agrees that containment of 
hazardous fragments after a bird strike present a serious concern, 
however containment requirements are beyond the scope of this 
rulemaking effort. The proposed rule, for large, small and medium birds 
has the same requirement, meaning the applicant must show that release 
of hazardous fragments through the engine casing following a bird 
strike is precluded. Also, Sec. 33.19 requires that the energy levels 
and trajectories of fragments resulting from rotor blade failure that 
lie outside the engine cases must be defined (e.g., fragments exiting 
through inlet structure). The FAA does not agree, however, that this 
concern warrants delay in issuing this final rule.
    One commenter states that a full flight engine configuration should 
be utilized for certification tests.
    The FAA agrees in principle. The test engine configuration must be 
fully representative of a type design engine insofar as bird ingestion 
requirements are concerned. Also, it is standard practice to use flight 
type inlets, cowls, and primary nozzles, or equivalents for these 
tests. The use of such flight type aircraft components are needed to 
evaluate the energy and trajectory of fragments which lie outside the 
engine type design cases. No changes to the proposed rule are required 
since compliance with the requirements will dictate the use of 
appropriate inlet and cowl hardware for any given design.
    One commenter states that a 10-percent tolerance band on 
certification test controlling parameters is excessive.
    The FAA does not agree. The 10-percent tolerance band addresses the 
Critical Ingestion Parameter (CIP), which is the parameter for a 
particular bird ingestion scenario that is most critical relative to 
the pass/fail criteria contained in the rule. The other controlling 
parameters must be maintained such that the CIP itself does not vary 
more than 10-percent. In practice, most controlling parameters can be 
maintained to a relatively tight tolerance, and this practice will not 
change. The AC will contain further guidance on one method, but not the 
only method, to show compliance with this requirement.
    One commenter states that the makeup of the rulemaking database is 
not clearly described within the NPRM.
    The FAA agrees in part. The database could be described in more 
detail. The database is made up of known revenue-

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service engine bird ingestion events from the time period from entry 
into service through September 1995. Data collections included 
International Civil Aviation Organization (ICAO) data, airframe 
manufacturer data, engine manufacturer data, FAA data and any other 
data presented that could be cross referenced to an actual engine 
ingestion. The data comes from a cross section of engine types, and for 
transport category aircraft engines it encompasses approximately 90 
million aircraft flights. The data points utilized are those which were 
identified as actual engine ingestion events, where an engine ingestion 
event was defined as the presence of bird debris within the engine 
inlet or engine flow paths. Bird debris was defined as feathers, flesh, 
or body fluids that could be identified as having come from a bird. 
Techniques used for identification of debris were visual identification 
of feathers, forensic laboratory methods, and black light 
identification of body fluid smears on the engine inlet flow path and 
engine structure. If the evidence positively indicated an ingestion, 
but a positive identification of the bird species could not be made, 
the data was entered as an ingestion without an associated weight. Data 
representing bird strikes to the aircraft structure (other than 
engines) was not utilized in the design of this rule. Simple bird 
species distribution data (i.e., population and size distributions 
occurring in nature) was also not utilized in the design of the rule.
    A series of bird ingestion data collection efforts, as described 
above, collated data for a variety of engine sizes and types. Three 
parameters were estimated from the data collection for events where the 
bird size, bird type, aircraft model, engine model, flight regime, and 
outcome where reasonably known. These were the single engine ingestion 
rate versus bird weight; multiple engine ingestion rate versus bird 
weight; and the ratio of the number of engine power loss events to the 
number of ingestion events versus bird weight. The probability of a 
dual engine power loss on a twin engine aircraft was computed by 
multiplying the square of the power loss ratio by the multiple engine 
ingestion rate for twin engine positions. Twin engine positions were 
defined as the inboard positions on four engine airplanes, the wing 
positions of three engine airplanes, and the wing positions on two 
engine airplanes. For the purpose of the above data reduction, a power 
loss was defined as 50-percent or more loss of power or thrust. The 
data was collected and evaluated in a manner which would provide a good 
representation of the bird ingestion threat to aircraft engines in 
service during that time period.
    The FAA does not agree, however, that the description of the 
database contained in the NPRM was deficient, or that this final rule 
should be delayed.
    Two commenters state that this rulemaking database does not reflect 
actual service experience, and is not accurate or complete.
    The FAA disagrees. As discussed in the paragraph above, the 
rulemaking database is comprised of data from actual engine bird 
ingestion events where the bird species, bird size, bird number, 
aircraft model, engine model, regime of flight, and outcome where all 
reasonably known. Also as noted above, for transport category aircraft 
engines, the database reflects known bird ingestion events encompassing 
approximately 90 million aircraft flights of experience covering a 
broad cross-section of aircraft types. This rulemaking database is a 
good representation of what aircraft engines have actually experienced 
over the past 25 years. Lastly, since this is the actual experience of 
the fleet, it also includes whatever effects there might be from 
increased bird populations in this time period.
    One commenter states that recent events have shown that the 
proposed requirements, relative to bird mass and flock size, are less 
severe than occur in nature.
    The FAA agrees in part. Events can occur that are beyond the 
severity of the proposed requirements. This was stated in the NPRM 
preamble. The proposed rule was not designed to encompass the worst 
possible combination of all factors, as this is impossible to predict, 
and would be beyond the capability of current engine technology. The 
FAA believes the proposed requirements are reasonable relative to the 
state goal of reducing the bird threat hazards to aircraft by an order 
of magnitude. It should also be noted that a number of new engine 
models have been designed and evaluated to these proposed standards, 
and have generally performed well in revenue service.
    The FAA does not agree that the possibility of a bird ingestion 
event more severe than already contemplated in the proposed rule should 
warrant a delay in issuing a final rule.
    One commenter states that there has been significant growth in some 
bird populations over the past 10 years.
    The FAA agrees in part. The FAA acknowledges that certain species 
of birds have experienced significant population and distribution 
increases over the past several years, and should be monitored for any 
effect on the bird threat to aircraft operations. The FAA does not 
believe, however, that this warrants a delay in issuing this final 
rule.
    Two commenters state that this rulemaking database focused only on 
past experience, and made no attempt to predict future changes to the 
bird threat.
    The FAA agrees in part. While this rulemaking database focused only 
on actual events which have occurred in revenue service, the rule was 
not designed to meet predicted future changes in the bird threat 
environment. The FAA believes it would be impossible to accurately 
predict threat changes, more or less in severity, as the overall 
experience base is a function of bird population, bird distribution, 
aircraft capability, engine capability, airport and airport 
environmental control measures, air traffic control operational 
requirements, air traffic control alert reports, and flight crew 
awareness. The FAA believes it is impossible to integrate these various 
factors into an accurate prediction of bird threat changes suitable for 
rulemaking, and believes that the possibility of such changes does not 
warrant delay in issuing this final rule. However, the FAA agrees that 
the factors noted above should be reviewed at periodic intervals to 
assure that the bird ingestion certification standards are adequate to 
meet the overall threat of bird ingestion, and that no individual 
factor is allowed to worsen to a significant degree.
    One commenter states that the large bird requirement should be 12-
15 lbs.
    The FAA does not agree. While birds larger in size than the 
standard for ``large birds'' in the proposed rule can occur in revenue 
service, a review service data indicates that the proposed sliding 
scale (4-8 lbs. as a function of inlet area) for the single large bird 
requirement is reasonable relative to the stated goal of reducing the 
hazards to aircraft by an order of magnitude. The FAA does not agree 
the large bird standard needs to be changed.
    One commenter states that the proposed requirement for 
Sec. 33.76(c)(2) needs to be revised to allow the use of certification 
data from previous programs.
    The FAA disagrees. It is not necessary for a rule to contain 
language allowing the use of existing certification data. Any 
certification data held by the applicant may be utilized provided that 
the data is applicable to the product in question, and approved by the 
FAA. The AC will contain a discussion on what sources of data could be

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acceptable for the purpose of compliance findings.
    One commenter states that the proposed requirements for 
Secs. 23.903 and 25.903 are not clear.
    The FAA disagrees. The text changes were required only to provide 
reference to new Sec. 33.76, and uses the same format as the previous 
rule.
    One commenter states that the proposed requirements for 
Secs. 23.903 and 25.903 will allow inappropriate use of previous engine 
bird ingestion certification requirements instead of new Sec. 33.76 
when determining engine model eligibility for new aircraft 
applications.
    The FAA disagrees. The proposed text is consistent with current 
Secs. 23.903 and 25.903, and allows flexibility for installation of pre 
Sec. 33.76 certification basis engines into new aircraft applications 
at the FAAs discretion. The FAA believes it would be inappropriate to 
preclude by regulation the installation of pre Sec. 33.76 engines which 
have demonstrated acceptable bird ingestion capabilities in revenue 
service. For transport category aircraft, the existing requirements 
under Secs. 21.21(b)(2), 25.903(a) and 25.1091(d)(2)/(e) have been 
identified as providing for the evaluation of proposed installations 
relative to bird ingestion service history. The FAA will review the 
application of these regulations to assure that they provide for the 
necessary level of evaluation of any proposed installation utilizing 
pre Sec. 33.76 model aircraft engines. Lastly, as part of this review, 
it was observed that current Sec. 25.1091 must be revised to include an 
appropriate reference to the new requirements of Sec. 33.76. Therefore, 
Sec. 25.1091 is also revised by this final rule action.
    One commenter states that the FAA air traffic control (ATC) 
operational procedures are now allowing high speed operations below 
10,000 ft. altitude, and this should be considered with respect to 
these bird ingestion requirements.
    The FAA agrees in part. This rule is based on the expectation that 
the majority of operations below 10,000 ft. would be at less than 250 
knots. However, studies into changing ATC operational procedures have 
allowed unrestricted operation at speeds above 250 knots near some 
Class B airports, and at altitudes where bird encounters are most 
likely to occur. The new small and medium bird requirements are 
structured to account for higher speeds. However the large bird 
requirement utilizes a 200-knots default bird speed value. Higher 
aircraft speeds at low altitudes could also result in shallower climb 
profiles, possibly resulting in an aircraft spending more time in a 
higher risk bird threat environment then previously assumed. Therefore, 
the FAA will institute a follow-on rulemaking action to determine 
whether additional changes to the bird requirements are necessary based 
on these operational considerations. Also, the FAA will include 
material in the AC to address this subject relative to the large bird 
test requirements. The FAA does not believe, however, that this 
operational consideration warrants delaying this final rule.
    One commenter states that the NPRM explanation for choosing the 200 
knots over a 250 knots bird speed value for large bird tests needs 
clarification.
    The FAA agrees in part. For a given turbine engine design, a 
specific bird speed will provide the least margin to the pass/fail 
criteria of Sec. 33.76. For critical static structure (e.g., inlet 
guide vane), the higher speed will generally be more severe due to 
simple momentum transfer at impact. However for critical rotating 
stages of blades, there will be an optimum bird speed which results in 
maximum damage to that rotating stage. Bird speeds faster or slower 
than this optimum will result in less severe damage. This is due to the 
combined effects of bird speed, rotor blade tangential velocity, and 
blade twist angle. The worst case combination of these factors will 
result in the highest bird since mass absorbed by the blade at the 
worst impact angle, and therefore results in the highest blade stresses 
at the blade's critical location. For example, most conventional high 
bypass turbofan designs will have critical speeds in the 150-220-knots 
range, depending upon specific fan blade design characteristics. While 
the FAA plans further review of this aspect of the large bird 
certification test, the FAA does not believe that this warrants delay 
in issuing this final rule.
    Five commenters state that the FAA should reconsider the JAA 
position of including a requirement addressing intermediate flocking 
birds greater than 2.5 lbs.
    The FAA agrees in part. The FAA agrees to reconsider the overall 
JAA position as part of future rulemaking study, and still believes 
that the Joint Aviation Requirements (JAR) and the FAA regulations 
should eventually be harmonized in this regard. The FAA does not agree, 
however, that the difference between this final rule and the JAA's 
current position warrants delay in issuing this final rule pending 
further study.
    Two commenters state that the FAA does not understand the JAA 
position on intermediate flocking birds.
    The FAA disagrees. The FAA understands that the rationale for the 
additional JAA intermediate flocking bird requirement is to ensure that 
new engines will have the same level of capability (for flocking birds 
greater than 2.5 lbs.) as current in-service engines have demonstrated. 
The FAA does believe that the new requirements of Sec. 33.76, overall, 
will provide a fleet of engines of overall increased capability when 
compared to the fleet of engines based on current Sec. 33.77 
requirements.
    Three commenters state that the FAA and JAA should consider 
alternatives to the JAA intermediate flocking bird requirement of JAR-E 
800(b)(2), as it does not meet its stated objective.
    The FAA agrees in part. The FAA agrees to participate in a new 
rulemaking study to develop a meaningful alternative to the JAR 
intermediate flocking bird requirement. The FAA does not agree that the 
12-percent unbalance requirement of proposed JAR-E 800(b)(2) can be 
relied upon to achieve the stated intent of the JAR-E rule as 
described. The FAA also does not believe that this final rule should be 
delayed pending any study of this issue.
    Three commenters state that the proposed requirements do not 
adequately cover the flocking bird range of 2.5-8 lbs.
    The FAA disagrees. The proposed requirements have taken into 
account flocking birds in this category based on (1) the historical 
performance of engines currently in service, and (2) based on the 
overall increased severity of the new requirements. The FAA believes 
that the new requirements of Sec. 33.76, overall, will provide a fleet 
of engines of increased capability in this regard when compared to be 
fleet of engines based on current Sec. 33.77 requirements. However, 
since the flocking bird capability in this bird size range may not be 
directly evaluated for each individual design at the time of 
certification, the FAA agrees to participate in a new rulemaking study 
of evaluate this comment further. The FAA does not agree, however, that 
this final rule should be delayed pending any study of that issue.
    One commenter states that the proposed requirements meet the 
flocking bird objections for conventional designs (e.g., for designs 
which the database directly represents).
    The FAA agrees that the rulemaking database and related assumptions 
which are part of this rule are most closely to the conventional 
designs which make up the database. Therefore, for each designs, there 
is a high degree of

[[Page 55852]]

confidence that this new rule's stated objective can be met.
    Two commenters state that the proposed requirements may not meet 
the flocking bird objectives for new unconventional design technologies 
which have no historical data from which to evaluate capability.
    The FAA agrees in part. The database on which this rule finds 
support, is made up of primarily conventional designs, and that the 
assumptions made when developing this rule most closely relate to those 
designs. However, it must be noted that the new Sec. 33.76 is generally 
a more severe set of requirements then currently Sec. 33.77, and that 
the overall effect of the new rule will be a world fleet of increased 
capability when compared to the world fleet based on current Sec. 33.77 
requirements. Therefore, the overall rule objective of decreasing the 
risk from bird ingestion events by an order of magnitude will be met at 
the world fleet level. Also, since the new requirements do not include 
specific test requirements for flocking birds greater than 2.5 lbs., 
the possibility exists for disparities in engine capability from one 
model series to another, regardless of conventional or unconventional 
designs. The FAA believes it prudent to address this concern by further 
review of available service data to determine whether the chosen 
standards sufficiently cover the level of safety desired for this rule, 
and to assure that the specific level of safety demonstrated by each 
engine model certified is acceptable. The FAA agrees to participate in 
a new rulemaking study to evaluate this comment further, but does not 
agree that this final rule should be delayed pending that study.
    Two commenters state that the proposed requirements do not provide 
any improvement in power loss rate over current requirements.
    The FAA disagrees. It must be noted that the new Sec. 33.76 is 
generally a more severe set of requirements then current Sec. 33.77, 
and that the overall effect of the new rule will be a world fleet of 
increased capability when compared to the world fleet based on current 
Sec. 33.77 requirements, of which power loss rate is one measure.
    One commenter states that there is no need for expanded flocking 
bird requirements beyond this proposal.
    The FAA agrees that new Sec. 33.76 will be beneficial to overall 
world fleet capability. The FAA also believes, however, that a new 
review of available is prudent to evaluate the current state of the 
bird threat in service, and that additional rulemaking action could 
result.
    Two commenters state that a new rulemaking study should be 
implemented to develop additional standards for run should be not be 
delayed pending further study.
    Finally, the FAA has made the following minor editorial changes to 
better clarify this rule. These changes do not affect the scope of the 
rule or change the intent of these sections.
    Sec. 33.76(a)(2) text was modified slightly to more clearly state 
the intent of the rule. There are no changes to the requirements.
    Sec. 33.76(b)(4) was revised to more clearly state the intent of 
the rule, which does not include an actual ``waiver'' of the large bird 
requirements as stated in the NPRM, but was intended to specify an 
additional method of showing compliance to these requirements using 
Sec. 33.76(a) certification data when appropriate. Therefore the actual 
certification substantiation requirements of this section are unchanged 
from the NPRM proposal, with the only change being a more accurate 
description of the compliance option under this subsection that is 
available to the applicant.
    It was determined that the title of Sec. 33.77 should be revised to 
specify the one remaining foreign object retained within this section 
(ice), and that for clarity and brevity the table of Sec. 33.77(e) is 
deleted, and the table's remaining pertinent information is included 
directly into the text of existing paragraph (e). No changes to the 
requirements have resulted from these additional format changes.
    Section 25.1091 was revised to include reference to Sec. 33.76. It 
was determine that the part 33 references within Sec. 25.1091 needed to 
be updated to account for this rulemaking action.
    After careful review of all the comments, the FAA has determined 
that air safety and the public interest require the adoption of the 
rule with the changes described.

Paperwork Reduction

    There are no new requirements for information collection associated 
with this rule that would require approval from the Office of 
Management and Budget pursuant to the Paperwork Reduction Act of 1995 
(44 U.S.C. 3507(d)).

International Compatibility

    In keeping with U.S. obligations under the Convention on 
International Civil Aviation, it is FAA policy to comply with 
International Civil Aviation Organization (ICAO) Standards and 
Recommends Practices to the maximum extent practicable. The FAA 
determined that there are no ICAO Standards and Recommended Practices 
that correspond to these regulations.

Regulatory Analyses and Assessments

    Changes to Federal regulations must undergo several economic 
analyses. First, Executive Order 12866 directs each Federal agency to 
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 requires agencies to analyze the 
economic impact of regulatory changes on small entities. Third, the 
Trade Agreements Act (19 U.S.C. 2531-2533) prohibits agencies from 
setting standards that create unnecessary obstacles to the foreign 
commerce of the United States. In developing U.S. standards, this Trade 
Act also requires agencies to consider international standards and, 
where appropriate, use them as the basis of U.S. standards. And fourth, 
the Unfunded Mandates Reform Act of 1995 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.)
    In conducting these analyses, FAA has determined this rule (1) has 
benefits which do justify its costs, is not a ``significant regulatory 
action'' as defined in the Executive Order and is ``significant'' as 
defined in DOT's Regulatory Policies and Procedures; (2) will not have 
a significant impact on a substantial number of small entities; (3) 
reduces barriers to international trade; and (4) does not impose an 
unfunded mandate on state, local, or tribal governments, or on the 
private sector. These analyses, available in the docket, are summarized 
below.

Regulatory Evaluation Summary

    Cost--this rule is the result of ARAC recommendations. Moreover, 
public comments were not received on the preliminary economic 
evaluation. Costs of the rule include one-time certification costs and 
recurrent fuel costs due to reduced fan efficiency. The FAA estimates 
that the rule will add $250,000 to $500,000 to each new engine model's 
certification costs, depending on engine inlet area. These 
certification costs will be incurred primarily in two areas. First, 
additional analysis required to verify the affects of a large bird 
impact on the front of the engine could necessitate a component test 
costing $250,000. Second, the rule

[[Page 55853]]

will require additional analysis or testing on the full fan assembly 
for engines with inlet areas greater than 2,092 square-inches. Such 
testing is estimated to cost approximately an additional $250,000 for 
those engines.
    In addition, the revised bird test weights could necessitate 
strengthening fan components, thereby affecting fan performance. The 
FAA estimates that reduced fan efficiency will result in a 0.2-percent 
increase in fuel consumption. On average, the FAA estimates that this 
will increase annual fuel costs by $4,770 per airplane, for airplanes 
equipped with new engines certificated to the standards of this rule.
    Benefits--Benefits associated with this rule include: (1) Averted 
fatalities and injuries, (2) averted property damage (primarily hull 
losses), and (3) reduced maintenance and repair costs. Based on 
historical accident information, the FAA estimates that the expected 
annual per-airplane benefit from averted airplane damage or loss is 
approximately $657. The expected annual benefit per-airplane from 
averted fatalities and injuries is $654 and $75, respectively.
    The estimated value of maintenance/repair savings associated with 
the rule is based on an analysis of the relationship between bird 
ingestion weight and the probability of damage. The FAA estimates that, 
on average, the rule will save operators approximately $4,654 per 
airplane per year.
    To compare the lifecycle costs and benefits of the rule, the 
evaluation utilizes a hypothetical representative engine certification. 
The engines are assumed to be installed on a notional twin-engine jet 
transport with a seating capacity of 161 (the average seating capacity 
of jet transports in commercial service in 1996). In addition, this 
analysis assumes the following: (1) Incremental engine certification 
costs equal $250,000 in year 0 and $250,000 in year 1; (2) production 
of engines commences in year 2, (3) engines are installed in aircraft 
and enter service beginning in year 3, (4) each engine has a 15-year 
service life, (5) 24 engines are produced per year for 10 years so that 
there are 240 total engines and 120 airplanes per certification, and 
(6) the discount rate is 7 percent. Under these conditions, the 
expected discounted benefits, at $4.333 million, exceed the discounted 
costs of $3.906 million.

Regulatory Flexibility Act

    The Regulatory Flexibility Act (RFA) of 1980, 5 U.S.C. 601-612, 
directs the FAA to fit regulatory requirements to the scale of the 
business, organizations, and governmental jurisdictions subject to the 
regulation. We are required to determine whether a proposed or final 
action will have a ``significant economic impact on a substantial 
number of small entities'' as defined in the Act. If we find that the 
action will have a significant impact, we must do a ``regulatory 
flexibility analysis.''
    This final rule will not have a significant economic impact on a 
substantial number of small entities. The final rule will apply only to 
newly designed turbine aircraft engines certificated in the future. 
Each new engine certification could affect two types of small entities: 
manufacturers of turbine engines and operators of aircraft.
    Manufacturers will be required to perform additional analysis or 
testing to demonstrate that the new bird ingestion requirements are 
met. There are nine turbine aircraft engine manufacturers with 
headquarters in the U.S. (this count includes subsidiaries of foreign 
entities and consortiums of domestic and/or foreign entities). 
Information available to the FAA indicates that only one--a U.S. 
manufacturer of small turbine engines has less than 1,500 employees, 
and therefore qualifies as a small business under SBA employment 
criteria. One entity is not considered a substantial number by the FAA. 
If all certification costs are assumed to be borne by the manufacturer, 
the FAA would conclude that with only one manufacturing firm being 
classified as ``small,'' there is not an impact on small business.
    In addition, the FAA analyzed the small business impact with a 
tougher criterion. The FAA assumes that all manufacturing costs will be 
borne by their customers who purchase new equipment. The rule is 
estimated to add about $250,000 for a small engine type produced by the 
single small entity: these are one-time certification costs. The FAA 
estimates that the rule will impose no incremental manufacturing costs. 
Aircraft operators will incur slightly higher engine prices and will 
pay increased operating or fuel costs due to the small decrease in 
engine efficiency (described in the full regulatory evaluation). 
According to FAA data, there are about 3,000 air carriers having less 
than 1,500 employees: approximately 100 air carriers operating under 
part 121 (or both part 121 and part 135), and 2,900 air carriers 
operating under part 135.
    Assuming conservatively that: (1) All incremental certification 
costs are passed on to the buyer/operator, (2) the manufacturer 
recovers incremental certification costs by applying a uniform price 
increase to engines produced during a 10-year production run, and (3) 
that the discount rate is 7 percent; then the FAA estimates that 
average new engine prices will increase by approximately $3,070 per 
larger engine and $1,587 per smaller engine. When these costs are 
amortized over the 15-year life of an engine (again, assuming a 7-
percent discount rate), the incremental annualized cost per new engine 
is approximately $315 and $163 for larger and smaller engines, 
respectively. Therefore, assuming a typical airplane has two engines, 
the incremental annualized costs for a large airplane is approximately 
$630 and the incremental annualized cost for a smaller airplane is 
approximately $326.
    For larger engines, the rule will also increase annual airplane 
operating costs as a result of the new medium bird ingestion 
requirements due to higher fuel consumption and, thus, costs. These 
requirements will have a negligible effect on smaller engines. On 
average, annual operating costs per large airplane, with engines newly 
certificated to the standards of this rule, are estimated to increase 
by approximately $4,770. However, the reduction in average annualized 
maintenance costs associated with the more damage-resistant engines is 
expected to approximately offset the incremental operating costs.
    Therefore, total annualized costs for operators of larger and 
smaller airplanes with new engines will be approximately $630 and $326 
per airplane, respectively. Consequently, the FAA certifies that the 
rule will not have a significant economic impact on a substantial 
number of small entities.

International Trade

    The Trade Agreement Act of 1979 prohibits Federal agencies from 
engaging in any standards of related activity that create unnecessary 
obstacles to the foreign commerce of the United States. Legitimate 
domestic objectives, such as safety, are not considered unnecessary 
obstacles. The statute also requires consideration of international 
standards and where appropriate, that they be the basis for U.S. 
standards. In addition, consistent with the Administration's belief in 
the general superiority and desirability of free trade, it is the 
policy of the Administration to remove or diminish, to the extent 
feasible, barriers to international trade, including both barriers 
affecting the export of American goods and services to foreign 
countries and barriers affecting the import of foreign goods and 
services into the U.S.
    Turbine engines are produced by United States and foreign 
companies. The FAA has assessed the potential

[[Page 55854]]

effect of this rule and has determined that it will impose the same 
costs on domestic and international entities, and will thus have a 
neutral trade impact.

Unfunded Mandates Reform Act

    The Unfunded Mandates Reform Act of 1995 (2 U.S.C. 1532-1538) 
requires the FAA to assess the effects of Federal regulatory actions on 
state, local, and tribal governments, and on the private sector of 
rules that contain a Federal intergovernmental or private sector 
mandate that exceeds $100 million in nay one year. This action does not 
contain such a mandate.

Executive Order 13132, Federalism

    The FAA has analyzed this final rule under the principles and 
criteria of Executive Order 13132, Federalism. The FAA determined that 
this action will not have a substantial direct effect on the States, or 
the relationship between the national Government and the States, or on 
the distribution of power and responsibilities among the various levels 
of government. Therefore, the FAA has determined that his final rule 
does not have federalism implications.

Plain Language

    In response to the June 1, 1998, Presidential Memorandum regarding 
the use of plain language, the FAA re-examined the writing style 
currently used in the development of regulations. The memorandum 
requires federal agencies to communicate clearly with the public. We 
are interested in your comments on whether the style of this document 
is clear, and any other suggestions you might have to improve the 
clarity of FAA communications that affect you. You can get more 
information about the Presidential memorandum and the plain language 
initiative at http://www.plainlanguage.gov.

Environmental Analysis

    FAA Order 1050.1D defines FAA actions that may be categorically 
excluded from preparation of a National Environmental Policy Act (NEPA) 
environmental assessment or environmental impact statement. In 
accordance with FAA Order 1050.ID, appendix 4, paragraph 4(j), this 
rulemaking action qualifies for a categorical exclusion.

Energy Impact

    The energy impact of the notice has been assessed in accordance 
with the Energy Policy and Conservation Act (EPCA) Public Law 94-163, 
as amended (43 U.S.C. 6362) and FAA Order 1053.1. It has been 
determined that the final rule is not a major regulatory action under 
the provisions of the EPCA.

List of Subjects

14 CFR Part 23

    Air transportation, Aircraft, Aviation safety, Safety.

14 CFR Part 25

    Air transportation, Aircraft, Aviation safety, Safety.

14 CFR Part 33

    Air transportation, Aircraft, Aviation safety, Safety.

The Amendment

    In consideration of the foregoing, the Federal Aviation 
Administration amends parts 23, 25 and 33 of Title 14, Code of Federal 
Regulations as follows:

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

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

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


    2. Section 23.903 is amended by revising paragraph (a)(2) to read 
as follows:


Sec. 23.903  Engines.

    (a) * * *
    (2) Each turbine engine and its installation must comply with one 
of the following:
    (i) Sections 33.76, 33.77 and 33.78 of this chapter in effect on 
December 13, 2000.
    (ii) Sections 33.77 and 33.78 of this chapter in effect on April 
30, 1998, or as subsequently amended before December 13, 2000; or
    (iii) Section 33.77 of this chapter in effect on October 31, 1974, 
or as subsequently amended before April 30, 1998, unless that engine's 
foreign object ingestion service history has resulted in an unsafe 
condition; or
    (iv) Be shown to have a foreign object ingestion service history in 
similar installation locations which has not resulted in any unsafe 
condition.
* * * * *

PART 25--AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES

    3. The authority citation for part 25 continues to read as follows:

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


    4. Section 25.903 is amended by revising paragraph (a)(2) to read 
as follows:


Sec. 25.903  Engines.

    (a) * * *
    (2) Each turbine engine must comply with one of the following:
    (i) Sections 33.76, 33.77 and 33.78 of this chapter in effect on 
December 13, 2000, or as subsequently amended; or
    (ii) Sections 33.77 and 33.78 of this chapter in effect on April 
30, 1998, or as subsequently amended before December 13, 2000; or
    (iii) Comply with Sec. 33.77 of this chapter in effect on October 
31, 1974, or as subsequently amended prior to April 30, 1998, unless 
that engine's foreign object ingestion service history has resulted in 
an unsafe condition; or
    (iv) Be shown to have a foreign object ingestion service history in 
similar installation locations which has not resulted in any unsafe 
condition.
* * * * *

    5. Section 25.1091 is amended by revising paragraph (e) to read as 
follows:


Sec. 25.1091  Air induction.

* * * * *
    (e) If the engine induction system contains parts or components 
that could be damaged by foreign objects entering the air inlet, it 
must be shown by tests or, if appropriate, by analysis that the 
induction system design can withstand the foreign object ingestion test 
conditions of Secs. 33.76, 33.77 and 33.78(a)(1) of this chapter 
without failure of parts or components that could create a hazard.

PART 33--AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES

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

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

    7. Section 33.76 is added to read as follows:


Sec. 33.76  Bird ingestion.

    (a) General. Compliance with paragraphs (b) and (c) of this section 
shall be in accordance with the following:
    (1) All ingestion tests shall 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.

[[Page 55855]]

    (2) The engine inlet throat area as used in this section to 
determine the bird quantity and weights will be established by the 
applicant and identified as a limitation in the installation 
instructions required under Sec. 33.5.
    (3) The impact to the front of the engine from the single large 
bird and the single largest medium bird which can enter the inlet must 
be evaluated. It must be shown that the associated components when 
struck under the conditions prescribed in paragraphs (b) or (c) of this 
section, as applicable, will not affect the engine to the extent that 
it cannot comply with the requirements of paragraphs (b)(3) and (c)(6) 
of this section.
    (4) For an engine that incorporates an inlet protection device, 
compliance with this section shall be established with the device 
functioning. The engine approval will be endorsed to show that 
compliance with the requirements has been established with the device 
functioning.
    (5) Objects that are accepted by the Administrator may be 
substituted for birds when conducting the bird ingestion tests required 
by paragraphs (b) and (c) of this section.
    (6) If compliance with the requirements of this section is not 
established, the engine type certification documentation will show that 
the engine shall be limited to aircraft installations in which it is 
shown that a bird cannot strike the engine, or be ingested into the 
engine, or adversely restrict airflow into the engine.
    (b) Large birds. Compliance with the large bird ingestion 
requirements shall be in accordance with the following:
    (1) The large bird ingestion test shall be conducted using one bird 
of a weight determined from Table 1 aimed at the most critical exposed 
location on the first stage rotor blades and ingested at a bird speed 
of 200-knots for engines to be installed on airplanes, or the maximum 
airspeed for normal rotocraft flight operations for engines to be 
installed on rotocraft.
    (2) Power lever movement is not permitted within 15 seconds 
following ingestion of the large bird.
    (3) Ingestion of a single large bird tested under the conditions 
prescribed in this section may not cause the engine to:
    (i) Catch fire;
    (ii) Release hazardous fragments through the engine casing;
    (iii) Generate loads greater than those ultimate loads specified 
under Sec. 33.23(a); or
    (iv) Lose the ability to be shut down.
    (4) Compliance with the large bird ingestion requirements of this 
paragraph may be shown by demonstrating that the requirements of 
Sec. 33.94(a) constitute a more severe demonstration of blade 
containment and rotor unbalance than the requirements of this 
paragraph.

         Table 1 to Sec.  33.76.--Large Bird Weight Requirements
------------------------------------------------------------------------
   Engine Inlet Throat Area (A)--Square/
          meters (square-inches)                Bird weight kg. (lb.)
------------------------------------------------------------------------
1.35 (2,092)> A...........................  1.85 (4.07) minimum, unless
                                             a smaller bird is
                                             determined to be a more
                                             severe demonstration.
1.35 (2,029) A 3.90 (6,045)....  2.75 (6.05)
3.90 (6,045) A.................  3.65 (8.03)
------------------------------------------------------------------------

    (c) Small and medium birds. Compliance with the small and medium 
bird ingestion requirements shall be in accordance with the following:
    (1) Analysis or component test, or both, acceptable to the 
Administrator, shall be conducted to determine the critical ingestion 
parameters affecting power loss and damage. Critical ingestion 
parameters shall include, but are not limited to, the affects of bird 
speed, critical target location, and first stage roto speed. 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 above ground level, but not less than 
V1 minimum for airplanes.
    (2) Medium bird engine tests shall be conducted so as to simulate a 
flock encounter, and will use the bird weights and quantities specified 
in Table 2. When only one bird is specified, that bird will be aimed at 
the engine core primary flow path; the other critical locations on the 
engine face area must be addressed, as necessary, by appropriate tests 
or analysis, or both. When two or more birds are specified in Table 2, 
the largest of those birds must be aimed at the engine core primary 
flow path, and a second bird must be aimed at the most critical exposed 
location on the first stage rotor blades. Any remaining birds must be 
evenly distributed over the engine face area.
    (3) In addition, except for rotorcraft engines, it must also be 
substantiated by appropriate tests or analysis or both, that when the 
full fan assembly is subjected to the ingestion of the quantity and 
weights of bird from Table 3, aimed at the fan assembly's most critical 
location outboard of the primary core flowpath, and in accordance with 
the applicable test conditions of this paragraph, that the engine can 
comply with the acceptance criteria of this paragraph.
    (4) A small bird ingestion test is not required if the prescribed 
number of medium birds pass into the engine rotor blades during the 
medium bird test.
    (5) Small bird ingestion tests shall be conducted so as to simulate 
a flock encounter using one 85 gram (0.187 lb.) bird for each 0.032 
square-meter (49.6 square-inches) of inlet area, or fraction thereof, 
up to a maximum of 16 birds. The birds will be aimed so as to account 
for any critical exposed locations on the first stage rotor blades, 
with any remaining birds evenly distributed over the engine face area.
    (6) Ingestion of small and medium birds tested under the conditions 
prescribed in this paragraph may not cause any of the following:
    (i) More than a sustained 25-percent power or thrust loss;
    (ii) The engine to be shut down during the required run-on 
demonstration prescribed in paragraphs (c)(7) or (c)(8) of this 
section;
    (iii) The conditions defined in paragraph (b)(3) of this section.
    (iv) Unacceptable deterioration of engine handling characteristics.
    (7) Except for rotorcraft engines, the following test schedule 
shall be used:
    (i) Ingestion so as to simulate a flock encounter, with 
approximately 1 second elapsed time from the moment of the first bird 
ingestion to the last.
    (ii) Followed by 2 minutes without power level movement after the 
ingestion.
    (iii) Followed by 3 minutes at 175-percent of the test condition.
    (iv) Followed by 6 minutes at 60-percent of the test condition.
    (v) Followed by 6 minutes at 40-percent of the test condition.
    (vi) Followed by 1 minute at approach idle.
    (vii) Followed by 2 minutes at 75-percent of the test condition.
    (viii) Followed by stabilizing at idle and engine shut down.
    The durations specified are times at the defined conditions with 
the power lever being moved between each condition in less than 10 
seconds.
    (8) For rotorcraft engines, the following test schedule shall be 
used:
    (i) Ingestion so as to simulate a flock encounter within 
approximately 1 second elapsed time between the first ingestion and the 
last.
    (ii) Followed by 3 minutes at 75-percent of the test condition.
    (iii) Followed by 90 seconds at descent flight idle.
    (iv) Followed by 30 seconds at 75-percent of the test condition.

[[Page 55856]]

    (v) Followed by stabilizing at idle and engine shut down. The 
duration specified are times at the defined conditions with the power 
being changed between each condition in less than 10 seconds.
    (9) Engines intended for use in multi-engine rotorcraft are not 
required to comply with the medium bird ingestion portion of this 
section, providing that the appropriate type certificate documentation 
is so endorsed.
    (10) If any engine operating limit(s) is exceeded during the 
initial 2 minutes without power lever movement, as provided by 
paragraph (c)(7)(ii) of this section, then it shall be established that 
the limit exceedence will not result in an unsafe condition.

    Table 2 to Sec.  33.76.--Medium Flocking Bird Weight and Quantity
                              Requirements
------------------------------------------------------------------------
 Engine Inlet Throat Area (A)--
  Square-meters (square-inches)      Bird quantity      Bird weight kg.
                                                             (lb.)
------------------------------------------------------------------------
0.05 (77.5)> A..................  none..............  ..................
.05 (77.5) A 0.10      1.................  0.35 (0.77)
 (155).
0.10 (155) A 0.20      1.................  0.45 (0.99)
 (310).
0.20 (310) A 0.40      2.................  0.45 (0.99)
 (620).
0.40 (620) A 0.60      2.................  0.70 (1.54)
 (930).
0.60 (930) A 1.00      3.................  0.70 (1.54)
 (1,550).
1.00 (1,550) A 1.35    4.................  0.70 (1.54)
 (2,092).
1.35 (2,092) A 1.70    1.................  1.15 (2.53)
 (2,635).
                                  plus 3............  0.70 (1.54)
1.70 (2,635) A 2.10    1.................  1.15 (2,53)
 (3,255).
                                  plus 4............  0.70 (1.54)
2.10 (3,255) A 2.50    1.................  1.15 (2.53)
 (3,875).
                                  plus 5............  0.70 (1.54)
2.50 (3,875) A 3.90    1.................  1.15 (2.53)
 (6045).
                                  plus 6............  0.70 (1.54)
3.90 (6045) A 4.50     3.................  1.15 (2.53)
 (6975).
4.50 (6975) A........  4.................  1.15 (2.53)
------------------------------------------------------------------------


        Table 3 to Sec.  33.76.--Additional Integrity Assessment
------------------------------------------------------------------------
 Engine Inlet Throat Area (A)--
  square-meters (square-inches)      Bird quantity      Bird weight kg.
                                                             (lb.)
------------------------------------------------------------------------
1.35 (2,092)> A.................  none..............  ..................
1.35 (2,092) A 2.90    1.................  1.15 (2.53)
 (4,495).
2.90 (4,495) A 3.90    2.................  1.15 (2.53)
 (6,045).
3.90 (6,045) A.......  1.................  1.15 (2.53)
                                  plus 6............  0.70 (1.54)
------------------------------------------------------------------------


    8. Section 33.77 is amended by revising the section heading, 
removing and reserving paragraphs (a) and (b), and by revising 
paragraphs (c), (d)(3), and (e) to read as follows:


Sec. 33.77   Foreign object ingestion--ice.

    (a) [Reserved]
    (b) [Reserved]
    (c) Ingestion of ice under the conditions of paragraph (e) of this 
section may not--
    (1) Cause a sustained power or thrust loss; or
    (2) require the engine to be shutdown.
    (d) * * *
    (3) The foreign object, or objects, stopped by the protective 
device will not obstruct the flow of induction air into the engine with 
a resultant sustained reduction in power or thrust greater than those 
values required by paragraph (c) of this section.
    (e) Compliance with paragraph (c) of this section must be shown by 
engine test under the following ingestion conditions:
    (1) Ice quantity will be the maximum accumulation on a typical 
inlet cowl and engine face resulting from a 2-minute delay in actuating 
the anti-icing system; or a slab of ice which is comparable in weight 
or thickness for that size engine.
    (2) The ingestion velocity will simulate ice being sucked into the 
engine inlet.
    (3) Engine operation will be maximum cruise power or thrust.
    (4) The ingestion will simulate a continuous maximum icing 
encounter at 25 degrees Fahrenheit.

    Issued in Washington, DC, on September 5, 2000.
Jane F. Garvey,
Administrator.
[FR Doc. 00-23175 Filed 9-13-00; 8:45 am]
BILLING CODE 4910-13-M