80 FR 42753 - Bird Strike Requirements for Transport Category Airplanes

DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration

Federal Register Volume 80, Issue 138 (July 20, 2015)

Page Range		42753-42756
FR Document		2015-17404

This document solicits public comments on the need for, and the possible scope of, changes to the bird strike certification requirements for transport category airplanes. The FAA is not currently proposing a specific regulatory action. The purpose of this request is to gather comments from airplane manufacturers and other interested parties on this subject.

Federal Register, Volume 80 Issue 138 (Monday, July 20, 2015)

[Federal Register Volume 80, Number 138 (Monday, July 20, 2015)]
[Proposed Rules]
[Pages 42753-42756]
From the Federal Register Online [www.thefederalregister.org]
[FR Doc No: 2015-17404]

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Proposed Rules
Federal Register
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This section of the FEDERAL REGISTER contains notices to the public of
the proposed issuance of rules and regulations. The purpose of these
notices is to give interested persons an opportunity to participate in
the rule making prior to the adoption of the final rules.

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Federal Register / Vol. 80, No. 138 / Monday, July 20, 2015 /
Proposed Rules

[[Page 42753]]

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2015-2490]

Bird Strike Requirements for Transport Category Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Request for comments on bird strike requirements for transport
category airplanes.

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

SUMMARY: This document solicits public comments on the need for, and
the possible scope of, changes to the bird strike certification
requirements for transport category airplanes. The FAA is not currently
proposing a specific regulatory action. The purpose of this request is
to gather comments from airplane manufacturers and other interested
parties on this subject.

DATES: Send comments by November 17, 2015.
Comments to: Todd.Martin@faa.gov.

ADDRESSES: Send comments, identified by Docket No. FAA-2015-2490, using
any of the following methods:
Federal eRulemaking Portal: Go to http://www.regulations.gov and follow the online instructions for sending your
comments electronically.
Mail: Send comments to Docket Operations, M-30; U.S.
Department of Transportation, 1200 New Jersey Avenue SE., Room W12-140,
West Building Ground Floor, Washington, DC 20590-0001.
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.
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 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: Todd Martin, Airframe and Cabin Safety
Branch, ANM-115, FAA, Transport Airplane Directorate, Aircraft
Certification Service, 1601 Lind Avenue SW., Renton, WA 98057-3356;
telephone (425) 227-1178; facsimile (425) 227-1232; email
Todd.Martin@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

The FAA invites interested persons to comment on the need for, and
the possible scope of, changes to the bird strike requirements for
transport category airplanes by submitting written data, views, or
arguments as they may desire. We have conducted a review of bird strike
data, and we are considering whether to revise the requirements, as
described in this document. We invite comments relating to the
technical or economic impact that might result from any of the rule
changes discussed herein, as well as any alternative suggestions.
Substantive comments should be accompanied by estimates of their
economic impact if possible. All comments received by the closing date
for comments will be considered by the FAA.

Background

Bird strike requirements for transport category airplanes are
specified in Title 14, Code of Federal Regulations (14 CFR), part 25,
and vary depending on the structural component being evaluated. Section
25.775 requires windshields and their supporting structure withstand,
without penetration, impact with a four-pound bird at VC
(design cruising speed) at sea level. This regulation has been in place
and is unchanged since part 25 was introduced in 1965.
Section 25.631 requires the empennage structure be designed to
assure continued safe flight after impact with an eight-pound bird at
VC at sea level, including consideration of control system
elements. This regulation was introduced at Amendment 25-23 (effective
May 8, 1970) as a result of the 1962 Vickers Viscount accident, which
was caused by impact with a swan, estimated to weigh between 12 and 17
pounds, that damaged the horizontal stabilizer and elevator.
Section 25.571 considers the rest of the airframe and requires the
airplane be capable of continued safe flight after impact with a four-
pound bird at VC at sea level, and .85 VC at 8000
feet. This regulation was introduced at Amendment 25-45 (effective
December 1, 1978) with some changes in the speed definition since then.
A speed criterion is provided at 8000 feet to ensure adequate bird
strike resistance capability up to that altitude.
In 1993, the FAA was developing a notice of proposed rulemaking to
establish a consistent eight-pound bird requirement for all structures.
The FAA decided instead to task the Aviation Rulemaking Advisory
Committee (ARAC) to evaluate the bird strike requirements and make
recommendations. The working group completed its deliberations in 2003
without reaching agreement. All members in the working group, except
the FAA, favored reducing the eight-pound bird requirement in Sec.
25.631 to four pounds, thus establishing a consistent four-pound bird
requirement for all structures. Other changes to the requirements were
considered by the group, but none were adopted. The working group
report is available at: http://www.faa.gov/regulations_policies/rulemaking/committees/documents/media/TAEgshT1-031593.pdf.
More recently, the National Transportation Safety Board (NTSB)
issued the following Safety Recommendation to the FAA as a result of a
fatal Cessna 500 accident that occurred in 2008: A-09-072, ``Revise the
bird-strike certification requirements for Part 25 airplanes so that
protection from in-flight impact with birds is consistent across all
airframe structures. Consider the most current military and

[[Page 42754]]

civilian bird-strike database information and trends in bird
populations in drafting this revision.''
To determine the adequacy of current bird strike certification
requirements, the FAA reviewed a number of reports, including the 2003
ARAC report, and other reports that address bird populations. We also
reviewed recent bird strike event data and compared the energy levels
of bird strike events to the energy levels prescribed in the current
requirements. We found numerous bird strike events in which the energy
level exceeded that specified in current part 25 requirements.

Sample of Bird Strike Event Data

The severity of a bird strike depends primarily on kinetic energy,
which is proportional to mass times velocity squared. Bird strikes
involving birds greater than four pounds occur often, but usually at
speeds below the design cruising speed, VC. Therefore, the
energy level of such strikes is usually below that specified in current
requirements. However, in some cases, that energy level is exceeded.
In each of the bird strike events shown below, the FAA estimates
that the energy level of the strike exceeded that specified in current
requirements. This is not an exhaustive list; these are just some
examples of events that occurred in the US since the 2008 Cessna
accident. For these events, we estimated the energy level of the event
and compared it to the current four-pound bird requirement specified in
Sec. Sec. 25.571 and 25.775.

Recent Examples of Bird Strike Events in Which the Energy Level Exceeded
the Current Airplane-Level Standard
[4 Pound Bird at VC]
------------------------------------------------------------------------

-------------------------------------------------------------------------
1. Energy level approximately 1.8 times current certification standard:
Date: 4 March 2008.
Aircraft: Cessna Citation Model 500.
Airport: Wiley Post (OK).
Phase of Flight: Climb (3,100' MSL (mean sea level)).
Estimated Airspeed: 198 KTAS (knots true airspeed).
Effect on Flight: Crashed.
Wildlife Species: American white pelican (mean weight 12.5 lb.).
Multiple birds.
Damage: Aircraft destroyed. Five fatalities. Shortly after takeoff,
the airplane flew through a flock of birds. There was no evidence
that any pieces of the airplane separated in flight. Bird residues
were identified on the right horizontal stabilizer and the right
side of the vertical stabilizer.
2. Energy level approximately 2.3 times current certification standard:
Date: 8 April 2008.
Aircraft: Bombardier Challenger 600.
Airport: Colorado Springs (CO).
Phase of Flight: Climb (8,000' MSL).
Estimated Airspeed: 260 KTAS.
Effect on Flight: Precautionary landing.
Wildlife Species: American white pelican (mean weight 12.5 lb.).
Multiple birds.
Damage: One bird penetrated the fuselage below the cockpit windows,
through the forward pressure bulkhead and into the cockpit. Both
engines ingested at least 1 bird. The #1 engine had fan damage; the
#2 engine lost power and had a dented inlet lip. Noise and wind in
the flightdeck. The left engine had high vibration levels. The
fuselage skin and forward pressure bulkhead were penetrated and
contained bird matter. The left engine thrust reverser torque box
assembly and pylon tracks were bent, and the engine cowl supports
were broken.
3. Energy level approximately 1.5 times current certification standard:
Date: 3 February 2009.
Aircraft: Boeing 757-200.
Airport: Denver International (CO).
Phase of Flight: Climb (7,500' MSL).
Estimated Airspeed: 270 KTAS (Airspeed not recorded. Airspeed
estimate assumes airplane was flying 10 knots below 250 KIAS speed
restriction. At 7500' MSL, 250 KIAS is approximately equal to 280
KTAS).
Effect on Flight: Emergency landing.
Wildlife Species: Bald eagle (mean weight 10.4 lb.). Single bird.
Damage: Bird hit right side of engine cowling making a large dent
before entering the engine where it damaged all fan blades.
4. Energy level approximately 4.2 times current certification standard:
Date: 10 August 2010.
Aircraft: Embraer 145.
Airport: Salt Lake City International (UT).
Phase of Flight: Approach (11,000' MSL).
Estimated Airspeed: 290 KTAS.
Effect on Flight: Landed using back up radio.
Wildlife Species: American white pelican (mean weight 12.5 lb.).
Multiple birds.
Damage: Birds punctured the nose of the aircraft between the nose
cone and windshield. The birds damaged the skin, stringers,
structural mounts and various avionics equipment. One bird
penetrated the airplane's skin and entered the forward avionics
bay. The captain lost a number of his primary instruments.
5. Energy level approximately 2.3 times current certification standard:
Date: 08 November 2010.
Aircraft: Bombardier DHC-8.
Airport: Los Angeles International (CA).
Phase of Flight: Approach (6,600' MSL).
Estimated Airspeed: 243 KTAS.
Effect on Flight: Emergency landing.
Wildlife Species: Common loon (mean weight 9.1 lb.). Single bird.

[[Page 42755]]

Damage: Bird impact resulted in a 12-inch hole in the right wing
leading edge, and internal structural damage to the right wing and
fuel tank.
6. Energy level approximately 1.2 times current certification standard:
Date: 15 November 2010.
Aircraft: Embraer 170.
Airport: Minneapolis-St. Paul International (MN).
Phase of Flight: Climb (5000' MSL).
Estimated Airspeed: 270 KTAS.
Effect on Flight: Precautionary landing.
Wildlife Species: Snow goose (mean weight 5.8 lb.). Multiple birds.
Damage: Radome, engine, fuselage. Autothrottle system disengaged.
First officer's primary flight display had alert flags for the
indicated airspeed and altitude parameters. Substantial damage to
the radome and its underlying structural components. The forward
pressure bulkhead web contained a dent and puncture. The left
engine compressor section was damaged.
7. Energy level approximately 1.4 times current certification standard:
Date: 01 November 2011.
Aircraft: Airbus 320.
Airport: Minneapolis-St Paul International (MN).
Phase of Flight: Climb (3300' MSL).
Estimated Airspeed: 220 KTAS.
Effect on Flight: Precautionary landing, emergency declared.
Wildlife Species: Tundra swan (mean weight 14.8 lb.). Single bird.
Damage: Bird hit right side of nose. Substantial damage to the
radome, nose, #2 engine and forward pressure bulkhead.
8. Energy level approximately 1.8 times current certification standard:
Date: 25 October 2012.
Aircraft: Boeing 757-200.
Airport: Boise Air Terminal (ID).
Phase of Flight: Climb (14,000' MSL).
Estimated Airspeed: 390 KTAS.
Effect on Flight: Precautionary landing.
Wildlife Species: Snow goose (mean weight 5.8 lb.). Multiple birds.
Damage: The radome was penetrated and the bulkhead was punctured.
There was extensive damage to the #2 engine.
9. Energy level approximately 2.2 times current certification standard:
Date: 12 October 2013.
Aircraft: Cessna 525.
Airport: Lincoln (NE).
Phase of Flight: Climb (6400' MSL).
Estimated Airspeed: 220 KTAS.
Effect on Flight: Precautionary landing.
Wildlife Species: American white pelican (mean weight 12.5 lb.).
Single bird.
Damage: Substantial damage to the outer right wing spar.
------------------------------------------------------------------------

These event data, including estimated airplane altitude and
airspeed, are derived from the following reports:
1. The FAA Wildlife Strike Database, available at: http://www.faa.gov/airports/airport_safety/wildlife.
2. The FAA Aviation Safety Information Analysis and Sharing (ASIAS)
System, available at: http://www.asias.faa.gov. This includes the FAA
Accident/Incident Data System, and the NTSB Aviation Accident and
Incident Data System.
3. National Transportation Safety Board. 2009. Aircraft Accident
Report: Crash of Cessna 500, N113SH, Following an In-Flight Collision
with Large Birds, Oklahoma City, Oklahoma, March 4, 2008. Aircraft
Accident Report NTSB/AAR-09/05. Washington, DC.
In addition to the events listed above, there are hundreds of
examples of bird strike events in which the energy level did not exceed
current requirements, but substantial damage to the airframe occurred.
In addition to structural damage, major damage to electrical, flight
control and fuel systems has occurred, and there have been dozens of
incidents in which the flight deck was penetrated.

Bird Population Trends

The bird strike threat has increased, especially the threat due to
larger birds. In a report commissioned by the FAA, Assessment of
Wildlife Strike Risk to Airframes; Herricks, Mankin, and Shaeffer;
December 2002; the authors wrote, ``The findings of this report,
supported by other literature, indicate that future operational
environments for aircraft can be expected to contain larger numbers of
birds, and larger numbers of birds with weights greater than four
pounds.''
According to Wildlife Strikes to Civil Aircraft in the United
States, 1990-2013, US Depts. of Transportation and Agriculture, July
2014: ``Many populations of large bird and mammal species commonly
involved in strikes have increased markedly in the last few decades and
adapted to living in urban environments, including airports. For
example, the resident (non-migratory) Canada goose population in the
USA and Canada increased from about 0.5 million to 3.8 million from
1980 to 2013 (Dolbeer et al. 2014, U.S. Fish and Wildlife Service.
2013). During the same time period, the North American snow goose
population increased from about 2.1 million to 6.6 million birds (U.S.
Fish and Wildlife Service. 2013). Other large-bird species that have
shown significant population increases from 1980 to 2012 include bald
eagles (6.4 percent annual rate of increase), wild turkeys (9.5
percent), turkey vultures (2.7 percent), American white pelicans (7.9
percent), double-crested cormorants (6.1 percent), sandhill cranes (5.9
percent), great blue herons (1.2 percent), and ospreys (3.0 percent,
Sauer et al. 2014). Dolbeer and Begier (2013) examined the estimated
population

[[Page 42756]]

trends and numbers for the 21 species of birds in North America with
mean body masses greater than 4 pounds and at least 10 strikes with
civil aircraft from 1990-2012. Of these 21 species, 17 had shown
population increases from 1990-2012 with a net gain of 17 million
birds. Previous research had documented that 13 of the 14 bird species
in North America with mean body masses greater than 8 pounds showed
significant population increases from 1970 to the early 1990s (Dolbeer
and Eschenfelder 2003).''

Airspeed Information

In the U.S., Sec. 91.117 prescribes a speed restriction of 250
knots indicated airspeed below 10,000 feet mean sea level. The 250 knot
speed restriction is also in place in Mexico and Canada, and in many
areas around the world, but not everywhere. Where this speed
restriction is in place, it provides a significant safety benefit with
respect to bird strikes.
While deviations to this speed restriction are allowed, and the
requirement is not global, it does indicate that limiting airspeed
below 10,000 feet is operationally feasible for transport category
airplanes. Indeed, to meet current bird strike criteria, some
manufacturers specify relatively low VMO and VC
airspeeds up to 8000 feet, that increase above that altitude. These
speed ``cutbacks'' at lower altitudes are beneficial for three reasons:
(1) They increase safety by reducing the energy of any bird strike that
occurs below 8000 feet, (2) they apply to all airspace, not just those
areas covered by US operating regulations, or those of other countries,
and (3) they reduce the bird strike speeds to which the airplane must
be designed.
To encourage these speed cutbacks, we believe establishing the bird
strike speed criteria based on VMO rather than VC
may be warranted. While most structures rules are based on
VC, allowing these very speed-dependent criteria to be based
on VMO may make the establishment of speed cutbacks easier
to achieve.

Summary of FAA Findings

Our review of bird strike event data and bird population data
indicates the following:
1. Bird strikes have occurred and will continue to occur at energy
levels that exceed the level provided by current requirements.
2. Numerous bird strikes have resulted in penetration into the
flight deck, mostly below the windshield, even at energy levels below
current requirements. Penetration of the cockpit obviously introduces a
number of significant risks to the airplane. Currently, there is no
requirement that specifically prohibits penetration of the flight deck
through structure other than the windshield.
3. The bird strike threat has increased, especially the threat due
to larger birds. Therefore, current fleet history may not be indicative
of what to expect in the future.
4. Bird strike events often involve more than one bird. Such
multiple bird strikes may result in structural damage in several areas,
pilot disorientation, engine failure and systems failures. Any one of
these effects can significantly reduce the controllability of the
airplane. Sections 25.571 and 25.631 assume a single bird strike,
rather than multiple bird strikes. The FAA believes that this single
bird strike approach is an adequate approach for airframe structure as
long as the single bird strike criteria are robust. By showing the
structure capable of withstanding a significant bird strike in any one
area, a bird strike to that area should not compound the hazard from
strikes in other areas.
5. Limiting airspeed below 10,000 feet is operationally feasible
for transport category airplanes. Bird strike data indicate numerous
damaging bird strikes have occurred above 8000 feet, but above 10,000
feet, bird strikes are rare. Therefore, expanding the envelope above
8000 feet, but limiting it at 10,000 feet, may be warranted.
6. Establishing reduced VMO and VC airspeeds
at lower altitudes provides a significant safety benefit with respect
to bird strikes.

Request for Comments

The FAA invites interested persons to comment on the need for, and
the possible scope of, changes to the bird strike requirements for
transport category airplanes by submitting written data, views, or
arguments as they may desire. We invite comments relating to the
technical or economic impact that might result from any considerations
discussed herein, as well as any alternative suggestions. In
particular, we invite information, comments, and opinion on the
following questions:
1. Should the bird weight requirement be applied consistently
across the airplane?
2. Should the bird weight requirement be increased, to eight pounds
or some other value?
3. Should a ``no-penetration'' requirement be applied to the entire
fuselage, not just the windshields?
4. Should the bird strike criteria be expanded to 10,000 feet?
5. Should the 0.85 speed reduction factor at 8000 feet, currently
specified in Sec. 25.571, be removed?
6. Should the speed criterion for bird strikes be based on
VMO rather than VC?

Conclusion

This document solicits public comments on the need for, and the
possible scope of, changes to the bird strike certification
requirements for transport category airplanes.

List of Subjects in 14 CFR Part 25

Aircraft, Aircraft safety.

Issued in Renton, Washington, on June 25, 2015.
Jeffrey E. Duven,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 2015-17404 Filed 7-17-15; 8:45 am]
BILLING CODE 4910-13-P

42753

Proposed Rules Federal Register
Vol. 80, No. 138

Monday, July 20, 2015

This section of the FEDERAL REGISTER process. DOT posts these comments, and is unchanged since part 25 was
contains notices to the public of the proposed without edit, including any personal introduced in 1965.
issuance of rules and regulations. The information the commenter provides, to Section 25.631 requires the
purpose of these notices is to give interested www.regulations.gov, as described in empennage structure be designed to
persons an opportunity to participate in the the system of records notice (DOT/ALL– assure continued safe flight after impact
rule making prior to the adoption of the final
rules.
14 FDMS), which can be reviewed at with an eight-pound bird at VC at sea
www.dot.gov/privacy. level, including consideration of control
Docket: Background documents or system elements. This regulation was
DEPARTMENT OF TRANSPORTATION comments received may be read at introduced at Amendment 25–23
http://www.regulations.gov at any time. (effective May 8, 1970) as a result of the
Federal Aviation Administration Follow the online instructions for 1962 Vickers Viscount accident, which
accessing the docket or go to Docket was caused by impact with a swan,
14 CFR Part 25 Operations in Room W12–140 of the estimated to weigh between 12 and 17
West Building Ground Floor at 1200 pounds, that damaged the horizontal
[Docket No. FAA–2015–2490]
New Jersey Avenue SE., Washington, stabilizer and elevator.
Bird Strike Requirements for Transport DC, between 9 a.m. and 5 p.m., Monday Section 25.571 considers the rest of
Category Airplanes through Friday, except Federal holidays. the airframe and requires the airplane be
FOR FURTHER INFORMATION CONTACT: capable of continued safe flight after
AGENCY: Federal Aviation Todd Martin, Airframe and Cabin Safety impact with a four-pound bird at VC at
Administration (FAA), DOT. Branch, ANM–115, FAA, Transport sea level, and .85 VC at 8000 feet. This
ACTION: Request for comments on bird Airplane Directorate, Aircraft regulation was introduced at
strike requirements for transport Certification Service, 1601 Lind Avenue Amendment 25–45 (effective December
category airplanes. SW., Renton, WA 98057–3356; 1, 1978) with some changes in the speed
telephone (425) 227–1178; facsimile definition since then. A speed criterion
SUMMARY: This document solicits public (425) 227–1232; email Todd.Martin@ is provided at 8000 feet to ensure
comments on the need for, and the faa.gov. adequate bird strike resistance
possible scope of, changes to the bird capability up to that altitude.
strike certification requirements for SUPPLEMENTARY INFORMATION:
In 1993, the FAA was developing a
transport category airplanes. The FAA is Comments Invited notice of proposed rulemaking to
not currently proposing a specific establish a consistent eight-pound bird
The FAA invites interested persons to
regulatory action. The purpose of this requirement for all structures. The FAA
comment on the need for, and the
request is to gather comments from decided instead to task the Aviation
possible scope of, changes to the bird
airplane manufacturers and other Rulemaking Advisory Committee
strike requirements for transport
interested parties on this subject. (ARAC) to evaluate the bird strike
category airplanes by submitting written
DATES: Send comments by November data, views, or arguments as they may requirements and make
17, 2015. desire. We have conducted a review of recommendations. The working group
Comments to: Todd.Martin@faa.gov. bird strike data, and we are considering completed its deliberations in 2003
ADDRESSES: Send comments, identified whether to revise the requirements, as without reaching agreement. All
by Docket No. FAA–2015–2490, using described in this document. We invite members in the working group, except
any of the following methods: comments relating to the technical or the FAA, favored reducing the eight-
• Federal eRulemaking Portal: Go to economic impact that might result from pound bird requirement in § 25.631 to
http://www.regulations.gov and follow any of the rule changes discussed four pounds, thus establishing a
the online instructions for sending your herein, as well as any alternative consistent four-pound bird requirement
comments electronically. suggestions. Substantive comments for all structures. Other changes to the
• Mail: Send comments to Docket should be accompanied by estimates of requirements were considered by the
Operations, M–30; U.S. Department of their economic impact if possible. All group, but none were adopted. The
Transportation, 1200 New Jersey comments received by the closing date working group report is available at:
Avenue SE., Room W12–140, West for comments will be considered by the http://www.faa.gov/regulations_
Building Ground Floor, Washington, DC FAA. policies/rulemaking/committees/
20590–0001. documents/media/TAEgshT1-
• Hand Delivery or Courier: Take Background 031593.pdf.
comments to Docket Operations in Bird strike requirements for transport More recently, the National
Room W12–140 of the West Building category airplanes are specified in Title Transportation Safety Board (NTSB)
Ground Floor at 1200 New Jersey 14, Code of Federal Regulations (14 issued the following Safety
mstockstill on DSK4VPTVN1PROD with PROPOSALS

Avenue SE., Washington, DC, between 9 CFR), part 25, and vary depending on Recommendation to the FAA as a result
a.m. and 5 p.m., Monday through the structural component being of a fatal Cessna 500 accident that
Friday, except Federal holidays. evaluated. Section 25.775 requires occurred in 2008: A–09–072, ‘‘Revise
• Fax: Fax comments to Docket windshields and their supporting the bird-strike certification requirements
Operations at 202–493–2251. structure withstand, without for Part 25 airplanes so that protection
Privacy: In accordance with 5 U.S.C. penetration, impact with a four-pound from in-flight impact with birds is
553(c), DOT solicits comments from the bird at VC (design cruising speed) at sea consistent across all airframe structures.
public to better inform its rulemaking level. This regulation has been in place Consider the most current military and

VerDate Sep<11>2014 16:10 Jul 17, 2015 Jkt 235001 PO 00000 Frm 00001 Fmt 4702 Sfmt 4702 E:\FR\FM\20JYP1.SGM 20JYP1

42754 Federal Register / Vol. 80, No. 138 / Monday, July 20, 2015 / Proposed Rules

civilian bird-strike database information exceeded that specified in current part requirements. However, in some cases,
and trends in bird populations in 25 requirements. that energy level is exceeded.
drafting this revision.’’ In each of the bird strike events
To determine the adequacy of current Sample of Bird Strike Event Data shown below, the FAA estimates that
bird strike certification requirements, The severity of a bird strike depends the energy level of the strike exceeded
the FAA reviewed a number of reports, primarily on kinetic energy, which is that specified in current requirements.
including the 2003 ARAC report, and proportional to mass times velocity This is not an exhaustive list; these are
other reports that address bird just some examples of events that
squared. Bird strikes involving birds
populations. We also reviewed recent occurred in the US since the 2008
greater than four pounds occur often,
bird strike event data and compared the Cessna accident. For these events, we
but usually at speeds below the design
energy levels of bird strike events to the estimated the energy level of the event
energy levels prescribed in the current cruising speed, VC. Therefore, the and compared it to the current four-
requirements. We found numerous bird energy level of such strikes is usually pound bird requirement specified in
strike events in which the energy level below that specified in current §§ 25.571 and 25.775.

RECENT EXAMPLES OF BIRD STRIKE EVENTS IN WHICH THE ENERGY LEVEL EXCEEDED THE CURRENT AIRPLANE-LEVEL
STANDARD
[4 Pound Bird at VC]

1. Energy level approximately 1.8 times current certification standard:
Date: 4 March 2008.
Aircraft: Cessna Citation Model 500.
Airport: Wiley Post (OK).
Phase of Flight: Climb (3,100′ MSL (mean sea level)).
Estimated Airspeed: 198 KTAS (knots true airspeed).
Effect on Flight: Crashed.
Wildlife Species: American white pelican (mean weight 12.5 lb.). Multiple birds.
Damage: Aircraft destroyed. Five fatalities. Shortly after takeoff, the airplane flew through a flock of birds. There was no evidence that any
pieces of the airplane separated in flight. Bird residues were identified on the right horizontal stabilizer and the right side of the vertical
stabilizer.
2. Energy level approximately 2.3 times current certification standard:
Date: 8 April 2008.
Aircraft: Bombardier Challenger 600.
Airport: Colorado Springs (CO).
Phase of Flight: Climb (8,000′ MSL).
Estimated Airspeed: 260 KTAS.
Effect on Flight: Precautionary landing.
Wildlife Species: American white pelican (mean weight 12.5 lb.). Multiple birds.
Damage: One bird penetrated the fuselage below the cockpit windows, through the forward pressure bulkhead and into the cockpit. Both
engines ingested at least 1 bird. The #1 engine had fan damage; the #2 engine lost power and had a dented inlet lip. Noise and wind in
the flightdeck. The left engine had high vibration levels. The fuselage skin and forward pressure bulkhead were penetrated and contained
bird matter. The left engine thrust reverser torque box assembly and pylon tracks were bent, and the engine cowl supports were broken.
3. Energy level approximately 1.5 times current certification standard:
Date: 3 February 2009.
Aircraft: Boeing 757–200.
Airport: Denver International (CO).
Phase of Flight: Climb (7,500′ MSL).
Estimated Airspeed: 270 KTAS (Airspeed not recorded. Airspeed estimate assumes airplane was flying 10 knots below 250 KIAS speed re-
striction. At 7500′ MSL, 250 KIAS is approximately equal to 280 KTAS).
Effect on Flight: Emergency landing.
Wildlife Species: Bald eagle (mean weight 10.4 lb.). Single bird.
Damage: Bird hit right side of engine cowling making a large dent before entering the engine where it damaged all fan blades.
4. Energy level approximately 4.2 times current certification standard:
Date: 10 August 2010.
Aircraft: Embraer 145.
Airport: Salt Lake City International (UT).
Phase of Flight: Approach (11,000′ MSL).
Estimated Airspeed: 290 KTAS.
Effect on Flight: Landed using back up radio.
Wildlife Species: American white pelican (mean weight 12.5 lb.). Multiple birds.
Damage: Birds punctured the nose of the aircraft between the nose cone and windshield. The birds damaged the skin, stringers, structural
mounts and various avionics equipment. One bird penetrated the airplane’s skin and entered the forward avionics bay. The captain lost a
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number of his primary instruments.
5. Energy level approximately 2.3 times current certification standard:
Date: 08 November 2010.
Aircraft: Bombardier DHC–8.
Airport: Los Angeles International (CA).
Phase of Flight: Approach (6,600′ MSL).
Estimated Airspeed: 243 KTAS.
Effect on Flight: Emergency landing.
Wildlife Species: Common loon (mean weight 9.1 lb.). Single bird.

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Federal Register / Vol. 80, No. 138 / Monday, July 20, 2015 / Proposed Rules 42755

RECENT EXAMPLES OF BIRD STRIKE EVENTS IN WHICH THE ENERGY LEVEL EXCEEDED THE CURRENT AIRPLANE-LEVEL
STANDARD—Continued
[4 Pound Bird at VC]

Damage: Bird impact resulted in a 12-inch hole in the right wing leading edge, and internal structural damage to the right wing and fuel
tank.
6. Energy level approximately 1.2 times current certification standard:
Date: 15 November 2010.
Aircraft: Embraer 170.
Airport: Minneapolis-St. Paul International (MN).
Phase of Flight: Climb (5000′ MSL).
Estimated Airspeed: 270 KTAS.
Effect on Flight: Precautionary landing.
Wildlife Species: Snow goose (mean weight 5.8 lb.). Multiple birds.
Damage: Radome, engine, fuselage. Autothrottle system disengaged. First officer’s primary flight display had alert flags for the indicated
airspeed and altitude parameters. Substantial damage to the radome and its underlying structural components. The forward pressure
bulkhead web contained a dent and puncture. The left engine compressor section was damaged.
7. Energy level approximately 1.4 times current certification standard:
Date: 01 November 2011.
Aircraft: Airbus 320.
Airport: Minneapolis-St Paul International (MN).
Phase of Flight: Climb (3300′ MSL).
Estimated Airspeed: 220 KTAS.
Effect on Flight: Precautionary landing, emergency declared.
Wildlife Species: Tundra swan (mean weight 14.8 lb.). Single bird.
Damage: Bird hit right side of nose. Substantial damage to the radome, nose, #2 engine and forward pressure bulkhead.
8. Energy level approximately 1.8 times current certification standard:
Date: 25 October 2012.
Aircraft: Boeing 757–200.
Airport: Boise Air Terminal (ID).
Phase of Flight: Climb (14,000′ MSL).
Estimated Airspeed: 390 KTAS.
Effect on Flight: Precautionary landing.
Wildlife Species: Snow goose (mean weight 5.8 lb.). Multiple birds.
Damage: The radome was penetrated and the bulkhead was punctured. There was extensive damage to the #2 engine.
9. Energy level approximately 2.2 times current certification standard:
Date: 12 October 2013.
Aircraft: Cessna 525.
Airport: Lincoln (NE).
Phase of Flight: Climb (6400′ MSL).
Estimated Airspeed: 220 KTAS.
Effect on Flight: Precautionary landing.
Wildlife Species: American white pelican (mean weight 12.5 lb.). Single bird.
Damage: Substantial damage to the outer right wing spar.

These event data, including estimated damage, major damage to electrical, have increased markedly in the last few
airplane altitude and airspeed, are flight control and fuel systems has decades and adapted to living in urban
derived from the following reports: occurred, and there have been dozens of environments, including airports. For
1. The FAA Wildlife Strike Database, incidents in which the flight deck was example, the resident (non-migratory)
available at: http://www.faa.gov/ penetrated. Canada goose population in the USA
airports/airport_safety/wildlife. and Canada increased from about 0.5
2. The FAA Aviation Safety Bird Population Trends
million to 3.8 million from 1980 to 2013
Information Analysis and Sharing The bird strike threat has increased, (Dolbeer et al. 2014, U.S. Fish and
(ASIAS) System, available at: http:// especially the threat due to larger birds.
Wildlife Service. 2013). During the same
www.asias.faa.gov. This includes the In a report commissioned by the FAA,
time period, the North American snow
FAA Accident/Incident Data System, Assessment of Wildlife Strike Risk to
goose population increased from about
and the NTSB Aviation Accident and Airframes; Herricks, Mankin, and
Shaeffer; December 2002; the authors 2.1 million to 6.6 million birds (U.S.
Incident Data System.
3. National Transportation Safety wrote, ‘‘The findings of this report, Fish and Wildlife Service. 2013). Other
Board. 2009. Aircraft Accident Report: supported by other literature, indicate large-bird species that have shown
Crash of Cessna 500, N113SH, that future operational environments for significant population increases from
Following an In-Flight Collision with aircraft can be expected to contain larger 1980 to 2012 include bald eagles (6.4
Large Birds, Oklahoma City, Oklahoma, numbers of birds, and larger numbers of percent annual rate of increase), wild
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March 4, 2008. Aircraft Accident Report birds with weights greater than four turkeys (9.5 percent), turkey vultures
NTSB/AAR–09/05. Washington, DC. pounds.’’ (2.7 percent), American white pelicans
In addition to the events listed above, According to Wildlife Strikes to Civil (7.9 percent), double-crested cormorants
there are hundreds of examples of bird Aircraft in the United States, 1990– (6.1 percent), sandhill cranes (5.9
strike events in which the energy level 2013, US Depts. of Transportation and percent), great blue herons (1.2 percent),
did not exceed current requirements, Agriculture, July 2014: ‘‘Many and ospreys (3.0 percent, Sauer et al.
but substantial damage to the airframe populations of large bird and mammal 2014). Dolbeer and Begier (2013)
occurred. In addition to structural species commonly involved in strikes examined the estimated population

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42756 Federal Register / Vol. 80, No. 138 / Monday, July 20, 2015 / Proposed Rules

trends and numbers for the 21 species obviously introduces a number of 5. Should the 0.85 speed reduction
of birds in North America with mean significant risks to the airplane. factor at 8000 feet, currently specified in
body masses greater than 4 pounds and Currently, there is no requirement that § 25.571, be removed?
at least 10 strikes with civil aircraft from specifically prohibits penetration of the 6. Should the speed criterion for bird
1990–2012. Of these 21 species, 17 had flight deck through structure other than strikes be based on VMO rather than VC?
shown population increases from 1990– the windshield.
2012 with a net gain of 17 million birds. 3. The bird strike threat has increased, Conclusion
Previous research had documented that especially the threat due to larger birds.
13 of the 14 bird species in North Therefore, current fleet history may not This document solicits public
America with mean body masses greater be indicative of what to expect in the comments on the need for, and the
than 8 pounds showed significant future. possible scope of, changes to the bird
population increases from 1970 to the 4. Bird strike events often involve strike certification requirements for
early 1990s (Dolbeer and Eschenfelder more than one bird. Such multiple bird transport category airplanes.
2003).’’ strikes may result in structural damage List of Subjects in 14 CFR Part 25
in several areas, pilot disorientation,
Airspeed Information engine failure and systems failures. Any Aircraft, Aircraft safety.
In the U.S., § 91.117 prescribes a one of these effects can significantly Issued in Renton, Washington, on June 25,
speed restriction of 250 knots indicated reduce the controllability of the 2015.
airspeed below 10,000 feet mean sea airplane. Sections 25.571 and 25.631 Jeffrey E. Duven,
level. The 250 knot speed restriction is assume a single bird strike, rather than Manager, Transport Airplane Directorate,
also in place in Mexico and Canada, and multiple bird strikes. The FAA believes Aircraft Certification Service.
in many areas around the world, but not that this single bird strike approach is [FR Doc. 2015–17404 Filed 7–17–15; 8:45 am]
everywhere. Where this speed an adequate approach for airframe
BILLING CODE 4910–13–P
restriction is in place, it provides a structure as long as the single bird strike
significant safety benefit with respect to criteria are robust. By showing the
bird strikes. structure capable of withstanding a DEPARTMENT OF TRANSPORTATION
While deviations to this speed significant bird strike in any one area,
restriction are allowed, and the a bird strike to that area should not Federal Aviation Administration
requirement is not global, it does compound the hazard from strikes in
indicate that limiting airspeed below other areas. 14 CFR Part 39
10,000 feet is operationally feasible for 5. Limiting airspeed below 10,000 feet
transport category airplanes. Indeed, to is operationally feasible for transport
[Docket No. FAA–2015–2462; Directorate
meet current bird strike criteria, some category airplanes. Bird strike data Identifier 2014–NM–224–AD]
manufacturers specify relatively low indicate numerous damaging bird
VMO and VC airspeeds up to 8000 feet, strikes have occurred above 8000 feet,
that increase above that altitude. These but above 10,000 feet, bird strikes are RIN 2120–AA64
speed ‘‘cutbacks’’ at lower altitudes are rare. Therefore, expanding the envelope
beneficial for three reasons: (1) They Airworthiness Directives; The Boeing
above 8000 feet, but limiting it at 10,000 Company Airplanes
increase safety by reducing the energy of feet, may be warranted.
any bird strike that occurs below 8000 6. Establishing reduced VMO and VC AGENCY:Federal Aviation
feet, (2) they apply to all airspace, not airspeeds at lower altitudes provides a Administration (FAA), DOT.
just those areas covered by US operating significant safety benefit with respect to
regulations, or those of other countries, bird strikes. Notice of proposed rulemaking
ACTION:
and (3) they reduce the bird strike (NPRM).
Request for Comments
speeds to which the airplane must be
designed. The FAA invites interested persons to SUMMARY: We propose to adopt a new
To encourage these speed cutbacks, comment on the need for, and the airworthiness directive (AD) for certain
we believe establishing the bird strike possible scope of, changes to the bird The Boeing Company Model 737–100,
speed criteria based on VMO rather than strike requirements for transport –200, –200C, –300, –400, –500 series
VC may be warranted. While most category airplanes by submitting written airplanes. This proposed AD was
structures rules are based on VC, data, views, or arguments as they may prompted by reports of cracked antenna
allowing these very speed-dependent desire. We invite comments relating to support channels, skin cracking
criteria to be based on VMO may make the technical or economic impact that underneath the number 2 very high
the establishment of speed cutbacks might result from any considerations frequency (VHF) antenna, and cracking
easier to achieve. discussed herein, as well as any in the frames attached to the internal
alternative suggestions. In particular, we support structure. This proposed AD
Summary of FAA Findings
invite information, comments, and would require repetitive inspections to
Our review of bird strike event data opinion on the following questions: determine the condition of the skin and
and bird population data indicates the 1. Should the bird weight requirement the internal support structure, and
following: be applied consistently across the follow-on actions including corrective
1. Bird strikes have occurred and will
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airplane? action as necessary. We are proposing
continue to occur at energy levels that 2. Should the bird weight requirement this AD to detect and correct skin
exceed the level provided by current be increased, to eight pounds or some cracking of the fuselage which could
requirements. other value? result in separation of the number 2
2. Numerous bird strikes have 3. Should a ‘‘no-penetration’’ VHF antenna from the airplane and
resulted in penetration into the flight requirement be applied to the entire rapid depressurization of the cabin.
deck, mostly below the windshield, fuselage, not just the windshields?
even at energy levels below current 4. Should the bird strike criteria be DATES: We must receive comments on
requirements. Penetration of the cockpit expanded to 10,000 feet? this proposed AD by September 3, 2015.

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Document Created: 2015-12-15 12:58:27
Document Modified: 2015-12-15 12:58:27

Category		Regulatory Information
Collection		Federal Register
sudoc Class		AE 2.7: GS 4.107: AE 2.106:
Publisher		Office of the Federal Register, National Archives and Records Administration
Section		Proposed Rules
Action		Request for comments on bird strike requirements for transport category airplanes.
Dates		Send comments by November 17, 2015.
Contact		Todd Martin, Airframe and Cabin Safety Branch, ANM-115, FAA, Transport Airplane Directorate, Aircraft Certification Service, 1601 Lind Avenue SW., Renton, WA 98057-3356; telephone (425) 227-1178; facsimile (425) 227-1232; email [email protected]
FR Citation		80 FR 42753
CFR Associated		Aircraft and Aircraft Safety

80 FR 42753 - Bird Strike Requirements for Transport Category Airplanes

DEPARTMENT OF TRANSPORTATIONFederal Aviation Administration

Federal Register Volume 80, Issue 138 (July 20, 2015)

DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration