[Federal Register Volume 83, Number 130 (Friday, July 6, 2018)]
[Proposed Rules]
[Pages 31479-31488]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2018-14270]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 33

[Docket No. FAA-2018-0568; Notice No. 18-02]
RIN 2120-AK83


Medium Flocking Bird Test at Climb Condition

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes the addition of a new test requirement to the 
airworthiness regulation addressing engine bird ingestion. The current 
regulation ensures bird ingestion capability of the turbofan engine fan 
blades, but the existing test conditions do not adequately demonstrate 
bird ingestion capability of the engine core. This proposed rule would 
require that, to obtain certification of a turbofan engine, a 
manufacturer must show that the engine core can continue to operate 
after ingesting a medium sized bird while operating at a lower fan 
speed associated with climb or landing. This new requirement would 
ensure that engines can ingest the largest medium flocking bird 
required by the existing

[[Page 31480]]

rule into the engine core at climb or descent conditions.

DATES: Send comments on or before September 4, 2018.

ADDRESSES: Send comments identified by docket number FAA-2018-0568 
using any of the following methods:
    <bullet> Federal eRulemaking Portal: Go to http://www.regulations.gov and follow the online instructions for sending your 
comments electronically.
    <bullet> Mail: Send comments to Docket Operations, M-30, U.S. 
Department of Transportation (DOT), 1200 New Jersey Avenue SE, Room 
W12-140, West Building Ground Floor, Washington, DC 20590-0001.
    <bullet> Hand Delivery or Courier: Take comments to Docket 
Operations in Room W12-140 of the West Building Ground Floor at 1200 
New Jersey Avenue SE, Washington, DC, between 9 a.m. and 5 p.m., Monday 
through Friday, except Federal holidays.
    <bullet> Fax: Fax comments to Docket Operations at 202-493-2251.
    Privacy: In accordance with 5 U.S.C. 553(c), DOT solicits comments 
from the public to better inform its rulemaking process. DOT posts 
these comments, without edit, including any personal information the 
commenter provides, to www.regulations.gov, as described in the system 
of records notice (DOT/ALL-14 FDMS), which can be reviewed at 
www.dot.gov/privacy.
    Docket: Background documents or comments received may be read at 
http://www.regulations.gov at any time. Follow the online instructions 
for accessing the docket or go to the Docket Operations in Room W12-140 
of the West Building Ground Floor at 1200 New Jersey Avenue SE, 
Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, 
except Federal holidays.

FOR FURTHER INFORMATION CONTACT: Alan Strom, Federal Aviation 
Administration, Engine and Propeller Standards Branch, Aircraft 
Certification Service, AIR-6A1, 1200 District Avenue, Burlington, 
Massachusetts 01803-5213; telephone (781) 238-7143; fax (781) 238-7199; 
email <a href="/cdn-cgi/l/email-protection#72131e131c5c0106001d1f321413135c151d04"><span class="__cf_email__" data-cfemail="3f5e535e51114c4b4d50527f595e5e11585049">[email protected]</span></a>.

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 issued under the authority described in 49 
U.S.C. 44701(a)(1). Under that section, the FAA is charged with, among 
other things, prescribing minimum safety standards for aircraft engines 
used in the flight of civil aircraft in air commerce. This proposed 
rule is within the scope of that authority because it updates existing 
regulations for certification of aircraft turbofan engines.

I. Overview of Proposed Rule

    This proposed rule would create an additional bird ingestion test 
for turbofan engines. The new requirements would be added to 14 CFR 
33.76, which covers engine testing for bird ingestion. This new test 
would ensure that engines can ingest the largest medium flocking bird 
(MFB) required by the existing rule, into the engine core at climb 
conditions. If the engine design is such that no bird material will be 
ingested into the engine core \1\ during the test at climb conditions, 
then the proposed rule would require a different test at approach 
conditions.
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    \1\ Turbofan engines have fan and core rotors. The fan or low 
pressure compressor is at the front of the engine. The core consists 
of additional compressor stages behind the fan.
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    The proposed test consists of firing at the engine core one MFB, 
equivalent to the largest bird currently required by Sec.  33.76(c) for 
the engine inlet throat area of the engine being tested, using either 
the following climb or descent testing conditions for an engine:
    (1) Testing for bird ingestion on climb. The test bird would be 
fired at 250-knots, with the mechanical engine fan speed set at the 
lowest expected speed when climbing through 3,000 feet altitude above 
ground level (AGL). After bird ingestion, the proposal would require 
that the engine comply with post-test run-on requirements similar to 
those in existing Sec.  33.76(d)(5), large flocking bird (LFB) test, 
except that, depending on the climb thrust of the engine, less than 50 
percent takeoff thrust may be allowed during the first minute after 
bird ingestion.
    (2) Testing for bird ingestion on descent. If the applicant 
determines that no bird mass will enter the core during the test at the 
250-knots/climb condition, then the applicant would be required to 
perform an alternative test to that described in the paragraph (1). For 
this test, the bird would be fired at 200-knots, with the engine 
mechanical fan speed set at the lowest fan speed expected when 
descending through 3,000 feet altitude AGL on approach to landing. 
Applicants would be required to comply with post-test run-on 
requirements that are the same as the final six (6) minutes of the 
existing Sec.  33.76(d)(5) post-test run-on requirements for large 
flocking birds (LFB). This is based on the assumption that the airplane 
will already be lined up with the runway.

Summary of Costs and Benefits

    The FAA estimates the annualized costs of this proposed rule to be 
$4 million, or $52 million over 27 years (at a seven percent present 
discount rate).\2\ The FAA estimates the annualized benefits of $5 
million, or $61 million over 27 years. The following table summarizes 
the benefits and costs of this proposed rule.
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    \2\ The FAA uses a 27-year period of analysis since it 
represents one complete cycle of actions affected by the proposed 
rule. One life cycle extends through the time required for 
certification, production of the engines, engine installation, 
active aircraft service, and retirement of the engines.

                                          Summary of Benefits and Costs
                                                  [$Millions] *
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                                                    27-year total present value             Annualized
                     Impact                      ---------------------------------------------------------------
                                                        7%              3%              7%              3%
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Benefits........................................           $61.0          $100.6            $5.1            $5.5
Costs...........................................            51.5            71.5             4.3             3.9
                                                 ---------------------------------------------------------------
    Net Benefits................................             9.4            29.1             0.8             1.6
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*Estimates may not total due to rounding. FAA uses discount rates of seven and three percent based on OMB
  guidance.


[[Page 31481]]

II. Background

A. Statement of the Problem

    On January 15, 2009, US Airways Flight 1549 (``Flight 1549'') took 
off from La Guardia Airport in New York City. On climb, at 
approximately 2,800 feet above ground level (AGL) and approximately 
230-knots indicated airspeed, the airplane struck a flock of migratory 
Canadian geese. Both engines ingested at least two birds. Both engine 
cores suffered major damage and total thrust loss.
    Flight 1549 was an Airbus Model A320 airplane. The A320 ``family'' 
of airplanes (i.e., Model A318/A319/A320/A321) and the Boeing Model 737 
airplanes are among the most frequently used airplanes, transporting a 
significant number of airline passengers around the world. Most 
transport airplanes and many business aircraft use turbofan engines 
that are susceptible to bird ingestion damage which, in some instances, 
has resulted in greater than 50 percent takeoff thrust loss. In twin-
engine airplanes, this amount of thrust loss in both engines can 
prevent the airplane to climb over obstacles or maintain altitude. This 
is an unsafe condition because it can prevent continued safe flight and 
landing.
    As a result of the Flight 1549 accident, the FAA began studying how 
to improve engine durability with respect to core engine bird 
ingestion.\3\ As a result of this tasking, the Aviation Rulemaking 
Advisory Committee (ARAC) working group produced a report titled, 
``Turbofan Bird Ingestion Regulation Engine Harmonization Working Group 
Report'', dated February 19, 2015.\4\ The ARAC working group report 
concluded that modern fan blades (such as those on the Flight 1549 
airplane engines) have relatively wider fan blade chords (width) than 
those in service when the current MFB ingestion test (codified in 14 
CFR 33.76(c)) was developed and adopted. The ARAC working group report 
also pointed out that the current MFB ingestion 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 descent phases of aircraft 
flight.
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    \3\ The FAA used prior studies to begin the review, such as 
flocking bird ingestion reports developed as Phase I and II reports 
for the current rule. The Phase III report, entitled, ``Aerospace 
Industries Association Bird Ingestion Working Group Interim Report--
January 2012'' was produced after the Flight 1549 event. The Phase 
III report is the most germane to this proposed rule, as it contains 
the latest bird ingestion data available through January 2009, 
including the Flight 1549 accident.
    \4\ The FAA accepted this report on March 19, 2015. The ARAC 
working group report included recommendations consistent with this 
proposed rule. The FAA will file in the docket copies of the 
referenced reports for this proposed rule.
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    When an engine ingests a bird, the amount of bird mass 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 result in the bird being moved further 
outboard and away from the core. That makes it less likely that bird 
material will enter the core during the current test compared to the 
proposed test. Conversely, a lower fan speed and higher airspeed, for a 
given fan blade width, makes it more likely that the bird material will 
enter the core.
    Currently, the MFB test is conducted using 100 percent power or 
thrust and 200 knots airspeed, simulating takeoff conditions. 
Consequently, the current MFB 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 existing test. 
Therefore, the existing small and medium flocking bird test prescribed 
in Sec.  33.76(c) do not provide the intended demonstration of core 
durability against bird ingestion for climb and descent conditions.

B. Related Actions

    Before proposing this rule, the FAA reviewed other actions taken by 
this agency to reduce threats of engine bird ingestion and concluded 
that these actions would not mitigate the specific risk discussed 
above. These actions include the following:
    (1) Advisory Circular (AC) 150/5200-33B, ``Hazardous Wildlife 
Attractants on or Near Airports'' provides guidance on certain land 
uses that have the potential to attract hazardous wildlife on or near 
public-use airports.
    (2) AC 150/5200-34A, ``Construction or Establishment of Landfills 
Near Public Airports'' provides guidance to minimize the impact to air 
safety when landfills, that often attract birds, are established near 
public airports.
    (3) 14 CFR 139.337, Wildlife hazard management, identifies 
certified Airport Operator responsibilities with respect to hazardous 
wildlife issues.
    (4) FAA Airport Safety website, Wildlife Strike Resources, 
available at http://www.faa.gov/airports/airport_safety/wildlife/resources/, provides information on wildlife strike prevention, 
database links, and bird strike/ingestion report forms, for use by 
airport authorities, airlines, industry, and the public.
    Most bird ingestions occur within five miles of an airport, and the 
ACs discussed above generally only apply within that radius. However, 
the Flight 1549 accident occurred more than five miles from La Guardia 
Airport, and the ingested birds were migratory. Therefore, while 
airport bird mitigation efforts are necessary to reduce engine bird 
ingestion incidents, these efforts will neither eliminate all flocking 
bird encounters, nor reduce the chance that such encounters could 
affect more than one engine on an airplane.

C. National Transportation Safety Board (NTSB) Recommendations

    The National Transportation Safety Board (NTSB) has issued two 
engine-related safety recommendations to the FAA:
    (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 LFB 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 working group addressed both NTSB safety recommendations. 
In response to NTSB safety recommendation A-10-64, the ARAC working 
group recommended the test in this proposed rule. The ARAC working 
group found that its recommendation would also address the intent of 
NTSB safety recommendation A-10-65, since the kinetic energy of the 
bird in the proposed rule is of the same magnitude as a LFB test.

[[Page 31482]]

III. Discussion of the Proposal

A. Hazard Identification

    There are two types of engine bird ingestion hazards related to 
turbofan-powered aircraft: Single- and multiple-engine bird ingestion. 
This proposed rule addresses the multiple-engine bird ingestion hazard, 
which can happen concurrently or sequentially, during the same flight.
    Multiple-engine bird ingestion occurs when the airplane flies 
through a bird flock that spans the distance between the engines. This 
can cause engine damage that prevents thrust production, which can then 
force an off-airport landing. The ARAC working group found that the 
existing rules and controls are not sufficient to address the threat 
from multi-engine core ingestion events.\5\
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    \5\ The existing controls to prevent these hazards include 
airport mitigation strategies (previously mentioned), and regulatory 
controls that include 14 CFR: (a) Part 25 installation requirements, 
concerning uncontained engine debris (e.g., Sec.  25.903(d)(1)) and 
minimizing hazards to the airplane from foreseeable engine 
malfunctions (such as Sec. Sec.  25.901(c) and 25.1309); (b) Section 
33.76 certification test requirements; and (c) Part 33 requirements 
(such as Sec. Sec.  33.19 and 33.94 containment requirements, Sec.  
33.17 fire protection requirements, etc.).
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B. Safety Risk Analysis

    The ARAC working group conducted a risk analysis to evaluate the 
bird ingestion threat using criteria that included (a) bird size class, 
(b) engine inlet size class, (c) phase of flight, and (d) recorded 
events with evidence of engine core flow path bird ingestion. The 
analysis included (a) the overall bird ingestion rate per flight, (b) 
rate of multi-engine ingestions per flight, (c) rate of power loss 
resulting in available power below 50 percent of takeoff per flight, 
and (d) the percent of events during each flight phase. Results from 
these analyses were used to determine:
    (1) If the civil air transport fleet is currently meeting its 
safety goal.
    (2) If engines in certain inlet size groups are performing worse 
than others.
    (3) If evidence of engine core ingestion indicates a greater chance 
of engine power loss (post-event power available less than 50 percent 
of takeoff thrust).
    (4) Which flight phase poses the highest threat to engines designed 
under existing regulations.
    The ARAC working group also analyzed the bird ingestion threat from 
(a) engine damage, and (b) engine failure to produce thrust due to 
stall, surge, etc. Thrust loss from bird damage generally refers to 
damage or failure of engine internal static and rotating parts. Damage 
that causes any of these hazards and those listed in Sec.  33.75 
(except complete inability to shut down the engine), would result in 
the pilot reducing thrust to idle, or shutting down the engine. 
Therefore, damage that causes any of the hazards listed in Sec.  
33.75(g)(2) \6\ was considered to have the same effect as internal 
damage to static and rotating engine parts.
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    \6\ The hazards are: (1) Non-containment of high-energy debris; 
(2) concentration of toxic products in the engine bleed air intended 
for the cabin sufficient to incapacitate crew or passengers; (3) 
significant thrust in the opposite direction to that commanded by 
the pilot; (4) uncontrolled fire; (5) failure of the engine mount 
system leading to inadvertent engine separation; (6) release of the 
propeller by the engine, if applicable; and (7) complete inability 
to shut the engine down.
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    The ARAC working group considered two engine performance conditions 
after bird ingestion, namely, less than 50 percent and more than 50 
percent takeoff thrust available. Less than 50 percent takeoff thrust 
available is a hazard, since it could prevent the airplane from 
climbing at a safe rate to avoid obstacles, or maintain altitude. More 
than 50 percent takeoff thrust available was not considered a hazard, 
as the airplane could still climb at a safe rate to avoid obstacles, or 
maintain altitude. Based on bird ingestion data from the Phase I 
through Phase III reports, the ARAC working group found it is extremely 
improbable that an airplane with more than two engines would have power 
loss greater than 50 percent of takeoff thrust on three or more 
engines.
    Since a surge or stall could occur upon bird ingestion, the ARAC 
working group assessed whether engine surge or stall, without 
significant physical damage to the engine's rotating parts, would 
prevent continued safe flight and landing. Based on its review of in-
service incidents, the ARAC working group determined that surge and 
stall are transitory events unlikely to cause an accident, since engine 
power can be recovered when the ingested material is cleared.
    Modern fan blades have relatively wider fan blade chords than those 
in service when the small and medium flocking bird core test in Sec.  
33.76(c) was developed. At takeoff, the fan speed is higher and the 
airspeed is lower than during climb. Therefore, the existing MFB core 
test of Sec.  33.76(c), does not provide the intended demonstration of 
core durability against bird ingestion for climb and descent 
conditions. In contrast to other phases of flight, takeoff conditions 
(which are simulated under the current MFB test) are more likely to 
move bird material away from the core section and into the fan flow 
path than climb and descent conditions (which are not simulated under 
the current MFB test). Testing the engine at the bird speed and fan 
speed representative of the airplane climb condition is more likely to 
result in significant bird material entering the engine core during the 
engine test. If the engine is designed so that no bird material enters 
the core during climb, then a test at the bird speed and fan speed 
associated with approach (lower bird speed but significantly lower fan 
speed) is another way to ensure significant bird material enters the 
core.
    The FAA agrees with the ARAC working group conclusion that, for 
modern engine designs, the existing Sec.  33.76(c) small and medium 
flocking bird test does not demonstrate engine core flow robustness 
against bird ingestion as intended.

C. Alternatives

    The ARAC working group determined there were six (6) MFB test 
options, as follows:
    (1) Conduct the existing test; then add a new and separate core 
test using a single bird at climb conditions.
    (2) Conduct the existing test, but leave out the core bird test 
described in Sec.  33.76(c)(2),\7\ add a new and separate core test 
using a single bird at climb conditions.
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    \7\ The MFB test defined in Sec.  33.76(c)(2) requires that 
largest of the birds fired at the engine must be aimed at the engine 
core primary flow path.
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    (3) Conduct the existing test without the existing core bird test; 
change the engine and bird speed conditions to match airplane climb 
conditions, and then fire the final bird.
    (4) Conduct the existing test using the existing core bird test; 
change the engine and bird speed conditions to match airplane climb 
conditions, and then fire the final bird.
    (5) Combine a new MFB engine core bird test with the existing LFB 
test. Fire an additional, MFB at the engine core, at least one minute 
after the LFB, but before the run-on portion of the test (for 
reference, the LFB is fired at 50 percent blade radius or higher, well 
outside the core).
    (6) Make no changes to the existing MFB regulation.
    The ARAC working group concluded that a modified Option 1 is 
necessary. The working group rejected options that would have 
eliminated the current core bird testing requirements set forth in 
Sec.  33.76(c)(2) once the new test is in place. The working group 
determined that the current requirements are still needed to test the 
ability of the engine

[[Page 31483]]

fan blades to withstand impact with a bird at the higher speeds present 
during takeoff. Because the new test proposed in this rule uses lower 
fan speed and higher bird speed than those specified in the current 
core bird testing requirements, it would be able to measure the ability 
of the engine core to withstand impact of bird mass that passes through 
the engine fan blades during the climb and descent phases of flight. 
However, the new test would not ascertain whether the engine fan blades 
could safely withstand a higher-kinetic-energy impact with a bird 
during the takeoff phase of flight while operating at 100 percent 
takeoff power or thrust (which is measured by the current testing).
    The FAA notes, however, that some aircraft are designed to operate 
such that their engine power during takeoff is nearly identical to 
their engine power during the climb and descent phases of flight. 
Because the takeoff and post-takeoff conditions for this group of 
engines are so similar, requiring an additional test that mimics post-
takeoff conditions would be needlessly repetitive for these engines, as 
the current testing already measures bird ingestion during takeoff 
conditions. Accordingly, this proposed rule would allow the new test to 
be combined with the existing test, if the climb fan rotor speed of the 
engine being tested is within 1 percent of the first fan stage rotor 
speed at 100 percent takeoff thrust or power.
    The new test would ensure that the core flow path of future engines 
remains sufficiently robust to maintain the civil fleet catastrophic 
hazard rate objective from bird ingestion. The ARAC working group chose 
this option since the other options did not address the safety risk, 
because they introduce unnecessary program test risk with no additional 
safety benefit.
    Because the Flight 1549 accident involved the ingestion of two 
birds into each engine, the FAA also considered requiring that, as part 
of the new test proposed in this rule, an engine must be capable of 
sustaining an ingestion of two MFBs into the engine core. However, the 
FAA rejected this approach as needlessly burdensome, because the 
simultaneous ingestion of two MFBs into the cores of multiple engines 
is an extremely rare event.

D. New Bird Ingestion Test

    Under this proposed rule, Sec.  33.76 would be amended to require 
turbofan engine manufacturers to demonstrate compliance with an 
additional bird ingestion test. The new test would require firing the 
largest MFB required by Sec.  33.76 (Table 2) at the engine core, at 
one of the following two conditions:
    The first test condition is at a speed of 250-knots, with the 
engine fan set at the speed associated with the lowest expected climb 
setting for the engine while the airplane is climbing through 3,000 
feet above ground level. The post-test run-on requirements would remain 
the same as the existing Sec.  33.76(d)(5). Because the climb setting 
may be significantly less than takeoff thrust, less than 50 percent 
takeoff thrust would be allowed up to one minute after bird ingestion. 
After one minute, the engine would be required to demonstrate at least 
50 percent takeoff thrust. The FAA notes that current MFB testing, 
which simulates takeoff conditions, does not allow a reduction below 50 
percent takeoff thrust. If this condition is present for only one 
minute during one of the post-takeoff phases of flight, it would not 
result in an unsafe condition because a pilot would have more time to 
respond to this issue without hazard. Requiring the engine to operate 
satisfactorily for one minute without throttle movement will ensure 
that the engine will not stall or shut down in the time it takes the 
pilot to understand that the engine has ingested a bird.
    The proposed requirements of the first condition above are intended 
to simulate the worst threat to the engine core in expected operating 
conditions. The maximum airspeed allowed below 10,000 feet is 250-knots 
indicated airspeed. Higher airspeed corresponds to less time for a bird 
to be in contact with the fan blades, reducing the likelihood that the 
bird would be centrifuged (moved radially outward) away from the core. 
Thus a test where the bird is fired at a higher speed is more likely to 
result in the bird going into the core as intended. The altitude, 3,000 
feet AGL, was chosen for two reasons: (1) 91 percent of bird ingestion 
events occur at or below 3,000 feet AGL and (2) during typical takeoff 
and climb profiles, engine speeds are increased and the aircraft climbs 
quickly after reaching 3,000 feet AGL. The post-test run-on 
requirements for the climb point would be the same as the existing LFB 
test (Sec.  33.76(d)(5)). The LFB post-test run-on requirements were 
chosen because the major threat to the engine core happens away from 
the airport when the airplane is well above the ground.
    The second test condition, should the applicant determine that no 
bird mass will enter the core during the test at the climb condition, 
must be successfully conducted at a speed of 200-knots indicated 
airspeed, with the engine fan set at the lowest expected mechanical fan 
speed while the airplane is descending through 3,000 feet AGL on 
approach to landing. The post-test run-on requirements would consist of 
the final seven minutes of the existing LFB 20-minute post-ingestion 
run-on requirement (Sec.  33.76(d)(5)) based on the assumption that the 
airplane would already be lined up with the runway during this phase of 
descent.
    The conditions for the approach test point are based on a typical 
aircraft approach profile. The post-test run-on requirements for the 
approach test point were selected based on the airplane approach being 
lined up with the runway and ready for landing. In addition, the 
possibility of having a multi-engine power loss (more than 50 percent 
loss per engine) on approach, combined with another simultaneous event 
that could prevent a safe landing, is considered extremely improbable. 
Finally, the approach test point would be run only if the engine has 
been designed to centrifuge all bird material away from the core of the 
engine during the takeoff and climb phases of flight. This test point 
would reduce the total risk of power loss from engine core bird 
ingestion.
    Additional bird ingestion testing at the 200-knot 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-knot climb 
condition may not be able to centrifuge away the same amount of bird 
material at the lower (200-knot) speed approach condition.
    The FAA notes that this proposed rule may result in the engine 
manufacturer having to run an additional bird ingestion test. If the 
manufacturer discovers during the 250-knot climb test that no bird 
material enters the engine core, then it is required to run the 200-
knot approach test. However, the FAA anticipates the two-test scenario 
is unlikely, because manufacturers would evaluate the design of its 
engine prior to engine bird ingestion testing. Thus, a manufacturer 
would be able to determine, prior to commencing certification testing, 
whether their engine will centrifuge all bird material away from the 
core. Based on this determination, the manufacturer would select the 
appropriate bird ingestion test (either the 250-knot climb or 200-knot 
approach test) proposed in this rule.
    The European Aviation Safety Agency (EASA) has notified the FAA 
that it

[[Page 31484]]

intends to incorporate requirements similar to those proposed here into 
its engine bird ingestion rule, CS-E 800. Incorporating the proposed 
test conditions into Sec.  33.76 would harmonize FAA requirements with 
EASA requirements and ensure that applicants would only need to comply 
with one set of regulations. Furthermore, incorporating these changes 
would prevent confusion within the FAA and EASA when validating engines 
developed under each other's regulations.
    With respect to the NTSB's recommendation to apply the LFB 
requirement to engines with inlet areas less than 2.5 square meters 
(3,875 square inches), the evidence from the Flight 1549 accident did 
not indicate a deficiency in current bird ingestion requirements for 
the fan blades. The Phase II report supports the FAA's conclusion that 
for engines with inlets of less than 2.5 square meters (3,875 square 
inches), a LFB test requirement is not necessary to meet the safety 
objective of preventing catastrophic effects from fan blade failure, 
for engines of that size.
    The FAA also considered whether to increase the required size of 
the bird aimed at the core during the MFB test as recommended by the 
NTSB. The FAA evaluated the relative effects of ingesting a MFB at the 
new proposed climb condition, against a LFB at the take-off condition 
in the current regulation (Sec.  33.76(d)). The LFB condition resulted 
in a smaller mass fraction of the bird entering the core (0.39 versus 
0.52 at the MFB condition). However, in terms of mass, a LFB fired into 
the core resulted in a 20 percent higher total mass into the core than 
the MFB. The FAA determined that the difference in impact energy 
delivered to the core inlet was insignificant between the LFB and MFB 
ingestion conditions (<plus-minus>2 percent). This is a result of the 
slower aircraft and engine fan rotor speed associated with the LFB 
ingestion criteria. For this reason, this proposed rule would not 
change the current LFB requirement (Sec.  33.76(d)).

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, this Trade Act requires agencies to consider 
international standards and, where appropriate, that they be the basis 
of U.S. standards. Fourth, the Unfunded Mandates Reform Act of 1995 
(Pub. L. 104-4) requires agencies to prepare a written assessment of 
the costs, benefits, and other effects of proposed or final rules that 
include a Federal mandate likely to result in the expenditure by State, 
local, or tribal governments, in the aggregate, or by the private 
sector, of $100 million or more annually (adjusted for inflation with 
base year of 1995; current value is $155 million). This portion of the 
preamble summarizes the FAA's analysis of the economic impacts of this 
proposed rule. The FAA suggest readers seeking greater detail read the 
full regulatory evaluation, a copy of which the FAA placed in the 
docket for this rulemaking.
    In conducting these analyses, the FAA has determined that this 
proposed rule: (1) Has benefits that justify its costs, (2) is not an 
economically ``significant regulatory action'' as defined in section 
3(f) of Executive Order 12866, (3) is ``non-significant'' as defined in 
DOT's Regulatory Policies and Procedures; (4) would not have a 
significant economic impact on a substantial number of small entities; 
(5) would not create unnecessary obstacles to the foreign commerce of 
the United States; and (6) would not impose an unfunded mandate on 
state, local, or tribal governments, or on the private sector by 
exceeding the threshold identified above. These analyses are summarized 
below.

I. Total Benefits and Costs of This Rule

    The FAA proposes the addition of a new test requirement to the 
engine bird ingestion airworthiness regulation. This new requirement 
would ensure that engines can ingest the medium flocking birds into the 
engine core at climb conditions. The ingestion of small and medium size 
birds can cause thrust loss from core engine bird ingestion if enough 
bird mass enters the engine core, which in turn can cause accidents or 
costly flight diversions. This proposed rule would add to the 
certification requirements of turbine engines a requirement that 
manufacturers must show that their engine cores can continue to operate 
after ingesting a medium sized bird while operating at a lower fan 
speed associated with climb out or landing. Engine manufacturers have 
the capability of producing such engines.
    The FAA estimates the annualized cost of the proposed rule to be $4 
million, or $52 million over 27 years (discounted at 7%).\8\ The FAA 
estimates annualized benefits of $5 million, or $61 million over 27 
years. The following table summarizes the benefits and costs of this 
proposed rule.
---------------------------------------------------------------------------

    \8\ The FAA uses a 27-year period of analysis since it 
represents one complete cycle of actions affected by the proposed 
rule. One life cycle extends through the time required for 
certification, production of the engines, engine installation, 
active aircraft service, and retirement of the engines.

                                          Summary of Benefits and Costs
                                                  [$Millions] *
----------------------------------------------------------------------------------------------------------------
                                                    27-Year total present value             Annualized
                     Impact                      ---------------------------------------------------------------
                                                        7%              3%              7%              3%
----------------------------------------------------------------------------------------------------------------
Benefits........................................           $61.0          $100.6            $5.1            $5.5
Costs...........................................            51.5            71.5             4.3             3.9
                                                 ---------------------------------------------------------------
    Net Benefits................................             9.4            29.1             0.8             1.6
----------------------------------------------------------------------------------------------------------------
* Estimates may not total due to rounding. The FAA uses discount rates of seven and three percent based on OMB
  guidance.


[[Page 31485]]

    Furthermore, this proposed rule would address two engine-related 
safety recommendations that the National Transportation Safety Board 
(NTSB) issued to the FAA: (1) A-10-64 and (2) A-10-65.
ii. Who is potentially affected by this rule?
    Aircraft operators and engine manufacturers.
iii. Assumptions
    <bullet> The analysis is conducted in constant dollars with 2016 as 
the base year.
    <bullet> Present value estimate follows OMB guidance of a 7 percent 
and a 3 percent discount rate.
    <bullet> The analysis period is 27 years with 10 years of new 
engine certificates.
    <bullet> Based on the actual production numbers of a common airline 
engine, it is estimated that about 220 engines are produced per year 
per certification.
    <bullet> The FAA estimates that the average life of an engine is 
27,500 cycles (flights) and that engines fly on average 1,748 flights 
per year. Therefore, the estimated average service life of an engine is 
about 16 years.
    <bullet> The FAA estimates the average fuel consumption will 
increase by $750 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 would have a significant economic impact on a substantial 
number of small entities. If the agency determines that it would, the 
agency must prepare a regulatory flexibility analysis as described in 
the Act. Two groups would be affected by this rule: aircraft operators 
and engine manufacturers.
    The FAA believes that this proposed rule would not have a 
significant economic impact on small aircraft operators. Affected 
operators would incur higher fuel burn costs due to increase in engine 
weight (heavier blading/components) and resultant consequent increase 
in total aircraft weight. The FAA estimates fuel burn costs of $750 per 
year per aircraft, which would not result in a significant economic 
impact for small aircraft operators.
    Similarly, the FAA believes that this proposed rule would not have 
a significant economic impact on engine manufacturers. The FAA 
identified one out of five engine manufacturers that meets the Small 
Business Administration definition of a small entity. The annual 
revenue estimate for this manufacturer is about $75 million.\9\ The FAA 
then compared that manufacturer's revenue with its annualized 
compliance cost. The FAA expects that the manufacturer's projected 
annualized cost of complying with this rule would be 0.7 percent of its 
annual revenue,\10\ which is not a significant economic impact.
---------------------------------------------------------------------------

    \9\ Source: http://www.manta.com.
    \10\ Ratio = annualized cost/annual revenue = $557,459/
$74,800,000 = 0.7 percent.
---------------------------------------------------------------------------

    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 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 proposed rule and determined that 
it has legitimate domestic safety objectives and would harmonize with 
forthcoming EASA standards. Accordingly, this proposed 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 proposed 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. According to the 1995 
amendments to the Paperwork Reduction Act (5 CFR 1320.8(b)(2)(vi)), an 
agency may not collect or sponsor the collection of information, nor 
may it impose an information collection requirement unless it displays 
a currently valid Office of Management and Budget (OMB) control number.
    The FAA has determined that there would be no new requirement for 
information collection associated with this proposed 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 proposed regulations. The proposed regulation 
is harmonized with changes the European Aviation Safety Agency (EASA) 
plans to make to its certification specifications.

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

[[Page 31486]]

paragraph 5-6.6(f) 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 FAA, when modifying its regulations in a manner 
affecting intrastate aviation in Alaska, to consider the extent to 
which Alaska is not served by transportation modes other than aviation, 
and to establish appropriate regulatory distinctions. 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 proposed rule under the principals and 
criteria of Executive Order 13132, Federalism. The agency has 
determined that this action would 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, would not have 
federalism implications.

B. Executive Order 13211, Regulations That Significantly Affect Energy 
Supply, Distribution, or Use

    The FAA analyzed this proposed rule under Executive Order 13211, 
Actions Concerning Regulations that Significantly Affect Energy Supply, 
Distribution, or Use (May 18, 2001). The FAA has determined that it 
would not be a ``significant energy action'' under the executive order 
and would not be 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 FAA has determined that this 
action would eliminate differences between U.S. aviation standards and 
those of other civil aviation authorities, by ensuring that Sec.  33.76 
remains harmonized with EASA CS-E 800.

D. Executive Order 13771, Reducing Regulation and Controlling 
Regulatory Costs

    Executive Order 13771 titled ``Reducing Regulation and Controlling 
Regulatory Costs,'' directs that, unless prohibited by law, whenever an 
executive department or agency publicly proposes for notice and comment 
or otherwise promulgates a new regulation, it shall identify at least 
two existing regulations to be repealed. In addition, any new 
incremental costs associated with new regulations shall, to the extent 
permitted by law, be offset by the elimination of existing costs. Only 
those rules deemed significant under section 3(f) of Executive Order 
12866, ``Regulatory Planning and Review,'' are subject to these 
requirements.
    This proposed rule is not expected to be an E.O. 13771 regulatory 
action because this proposed rule is not significant under E.O. 12866.

VI. Additional Information

A. Comments Invited

    The FAA invites interested persons to participate in this 
rulemaking by submitting written comments, data, or views. The agency 
also invites comments relating to the economic, environmental, energy, 
or federalism impacts that might result from adopting the proposals in 
this document. The most helpful comments reference a specific portion 
of the proposal, explain the reason for any recommended change, and 
include supporting data. To ensure the docket does not contain 
duplicate comments, commenters should send only one copy of written 
comments, or if comments are filed electronically, commenters should 
submit only one time. Commenters must identify the docket or notice 
number of this rulemaking.
    The FAA will file in the docket all comments received, as well as a 
report summarizing each substantive public contact with FAA personnel 
concerning this proposed rule. Before acting on this action, the FAA 
will consider all comments it receives on or before the closing date 
for comments. The FAA will consider comments filed after the comment 
period has closed if it is possible to do so without incurring expense 
or delay. The agency may change this proposal in light of the comments 
it receives.
    Proprietary or Confidential Business Information: Commenters should 
not file proprietary or confidential business information in the 
docket. Such information must be sent or delivered directly to the 
person identified in the FOR FURTHER INFORMATION CONTACT section of 
this document, and marked as proprietary or confidential. If submitting 
information on a disk or CD ROM, mark the outside of the disk or CD 
ROM, and identify electronically within the disk or CD ROM the specific 
information that is proprietary or confidential.
    Under 14 CFR 11.35(b), if the FAA is aware of proprietary 
information filed with a comment, the agency does not place it in the 
docket. It is held in a separate file to which the public does not have 
access, and the FAA places a note in the docket that it has received 
it. If the FAA receives a request to examine or copy this information, 
it treats it as any other request under the Freedom of Information Act 
(5 U.S.C. 552). The FAA process such a request under Department of 
Transportation procedures found in 49 CFR part 7.

B. Availability of Rulemaking Documents

    An electronic copy of rulemaking documents may be obtained from the 
internet by
    1. Searching the Federal eRulemaking Portal (http://www.regulations.gov);
    2. Visiting the FAA's Regulations and Policies web page at http://www.faa.gov/regulations_policies or
    3. Accessing the Government Printing Office's web page at http://www.access.gpo.fdsys/.
    Copies may also be obtained by sending a request to the Federal 
Aviation Administration, Office of Rulemaking, ARM-1, 800 Independence 
Avenue SW, Washington, DC 20591, or by calling (202) 267-9680. 
Commenters must identify the docket or notice number of this 
rulemaking.
    All documents the FAA considered in developing this proposed rule, 
including economic analyses and technical reports, may be accessed from 
the internet through the Federal eRulemaking Portal referenced in item 
(1) above.

List of Subjects in 14 CFR Part 33

    Bird ingestion.

The Proposed Amendment

    In consideration of the foregoing, the Federal Aviation 
Administration proposes to amend 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.


[[Page 31487]]


0
2. Amend Sec.  33.76 by revising paragraph (a)(1) and adding paragraph 
(e) to read as follows:


Sec.  33.76   Bird ingestion.

    (a) * * *
    (1) Except as specified in paragraph (d) or (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.
* * * * *
    (e) Core engine 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) may be used to satisfy 
this requirement only 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) 250-knot climb core engine 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 fan stage or stages that, 
on a standard day, produces the lowest expected power or thrust 
required during climb through 3,000 feet above ground level.
    (B) Bird weight must be the largest specified in Table 2 of this 
section for the engine inlet area.
    (C) Ingestion must be at 250-knots bird speed.
    (D) The bird must be aimed at the first exposed rotating fan 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) Conditions 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 to paragraph (e)(1)(iii) introductory text: Durations 
specified are times at the defined conditions.

    (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. Power lever movement in this condition is limited to 
10 seconds or less.
    (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) 200-knot approach flocking bird core engine test (performed 
only if test or analysis shows no bird material will be ingested into 
the core during the test at the conditions of paragraph (e)(1) of this 
section):
    (i) Test requirements are as follows:
    (A) Before ingestion, the engine must be stabilized 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 above ground level.
    (B) Bird mass and weight must be the largest specified in Table 2 
of this section for the engine inlet area.
    (C) Ingestion must be 200-knot bird speed.
    (D) Bird must be aimed at the first exposed rotating fan 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) Conditions 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 to paragraph (e)(2)(iii) introductory text: Durations 
specified are times at the defined conditions.

    (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.
    (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.
    (3) Applicants must show that an unsafe condition will not result 
if any engine operating limit is exceeded during the run-on period.
    (4) The core engine flocking bird test of this paragraph (e) may be 
combined with the MFB test of paragraph (c) of this section, if the 
climb fan rotor speed calculated in paragraph (e)(1) of this section is 
within 1 percent of the first fan 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) of this section, the test conducted 
under paragraph (c) of this section satisfies the requirements of this 
section if the bird aimed at the core of the engine meets the bird 
ingestion speed criteria of either:
    (i) Paragraph (e)(1)(i)(C) of this section; or
    (ii) Paragraph (e)(2)(i)(C) of this section if testing or validated 
analysis shows that no bird material will be ingested into the engine 
core during the test.


[[Page 31488]]


    Issued in Washington, DC, on June 21, 2018.
David W. Hempe,
Deputy Executive Director for Regulatory Operations, Aircraft 
Certification Service.
[FR Doc. 2018-14270 Filed 7-5-18; 8:45 am]
 BILLING CODE 4910-13-P


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