Aircraft
Certification Service Washington, DC U.S. Department of Transportation Federal Aviation Administration
AIR-21-17
September 13, 2021
This is information only. Recommendations
aren’t mandatory.
Introduction
This Special Airworthiness Information Bulletin (SAIB) provides
information to help all rotorcraft owners, operators, aircrew, and
passengers understand rotorcraft bird strike safety standards. This
SAIB also introduces a voluntary Rotorcraft Safety Promotion Concept
(RSPC) to encourage installation of safety enhancing designs, use of
certain safety equipment, and adoption of operational procedures to
mitigate the risk of bird strike for both Part 27 and Part 29
rotorcraft.
The subject matter of this SAIB does not warrant airworthiness
directive (AD) action under 14 CFR Part 39. However, operating a
rotorcraft with bird strike safety enhancements and following
operational mitigations may reduce the probability of a bird strike
occurring. Additionally, some of these recommendations may reduce the
likelihood or severity of injuries and limit the damage to the
rotorcraft if a bird strike occurs.
Background
Rotorcraft have a unique vulnerability to bird strike in comparison to
other aircraft. Most rotorcraft flight profiles are in the low altitude
environment below 3,500 feet AGL, an airspace that is the also the most
densely populated with birds. In their 2017 report to the Aviation
Rulemaking Advisory Committee, the Rotorcraft Bird Strike Working Group
(RBSWG) cited that more than 90% of bird strikes occurred in this
airspace. The outcome of a bird strike to a rotorcraft may vary from
benign to catastrophic in nature, depending on variables such as the
speed of the rotorcraft, the type of bird, size of bird, and the
location on the rotorcraft where the bird impact occurs. A bird strike
may lead to a loss of control in-flight, either through damage to a
critical system component on the rotorcraft or by penetrating into the
crew area and incapacitating the pilot. For a thorough explanation of
the risk of bird strike to rotorcraft, the full report for the RBSWG is
publicly available at:
https://www.faa.gov/regulations_policies/rulemaking/committees/documents/index.cfm/search/searchResults.
On August 8, 1996, the FAA issued airworthiness standards to protect
against bird strike through Amendment 29-40 of 14 CFR Part 29, section
29.631. While this safety enhancing regulation was limited in
applicability to newly type certificated transport category rotorcraft,
these protections can also be utilized on Part 27 and other Part 29
rotorcraft that fall outside the applicability of the regulation. This
offers a particularly significant safety opportunity for Part 27
rotorcraft since they make up about 80-90% of the U.S. registered
rotorcraft fleet.
A rotorcraft designed to 14 CFR 29.631 requirements increases the
protection to occupants and thus reduces the likelihood of a fatal or
incapacitating injury if a bird strike occurs. Some of the same safety
enhancing design features that are required of newly type certificated
Part 29 rotorcraft may be voluntarily pursued to increase the bird
strike protection for Part 27 rotorcraft and also for the Part 29
rotorcraft that were not required to meet the regulation. There is also
optional safety enhancing equipment available that offers bird strike
deterrence capability that may prevent the bird strike from occurring
in the first place.
Aside from design and equipment considerations, operational mitigations
can reduce the likelihood of a bird strike by pilots knowing and
understanding bird flight patterns and taking appropriate preemptive
actions. Finally, personal protective equipment is another aspect of
operational mitigation that is important in preventing occupant injury
or pilot incapacitation for cases where the bird strike penetrates
through the windshield.
Recommendations
The FAA recommends if you own, operate, or will occupy a seat in a
rotorcraft as a pilot, aircrew, or passenger, you consider the
following two options in order to minimize the potential for bird
strike and maximize the protection to you if a bird strike occurs.
Rotorcraft Design and Equipment Safety Enhancement Options
The FAA is introducing a new
resource, the Rotorcraft Safety Promotion Concept (RSPC), to better
inform and educate stakeholders about the continuum of voluntary design
and equipment safety enhancement options related to bird strike. The
RSPC is available at
https://www.faa.gov/aircraft/air_cert/design_approvals/rotorcraft/media/rot_Birdstrike_RSPC.pdf.
The different areas on the continuum each offer a different safety
benefit in terms of bird strike deterrence or protection. Stakeholders
are encouraged to voluntarily use this resource to determine the design
and equipment features that best fit their operational needs, available
resources, and personal risk tolerances.
For stakeholders interested in the Part 29 rotorcraft that meet the
bird strike protection requirements of 14 CFR 29.631, the FAA maintains
a list at
https://www.faa.gov/aircraft/air_cert/design_approvals/rotorcraft/media/rot_Birdstrike_Compliant_List.pdf.
The RSPC is intended to assist you in making an informed risk-based
decision. If you are not familiar with some of the terms used to
describe different areas on the RSPC continuum in this SAIB, the FAA
recommends the following actions to help you to determine the bird
strike design and equipment capability of a specific rotorcraft.
For those considering owning or leasing a rotorcraft:
Refer to this SAIB and ask the
rotorcraft manufacturer about the bird strike protection and mitigation
of their product compared to the RSPC continuum. Rotorcraft
manufacturers can provide you information on available FAA approved
design modifications that will improve bird strike protection and
mitigation.
For current owners and operators:
Refer to this SAIB and ask your
local FAA Flight Standards District Office (FSDO) about the bird strike
protection and mitigation of your rotorcraft compared to the RSPC
continuum. The FSDO may also connect you to an FAA Aircraft
Certification Office (ACO) to assist in answering this question.
Rotorcraft manufacturers can also provide you information on available
FAA approved design modifications that will improve bird strike
protection and mitigation.
For pilots and aircrew:
Refer to this SAIB and ask your
operator about the bird strike protection and mitigation of their
rotorcraft compared to the RSPC continuum.
For passengers:
Refer to this SAIB and ask the
operator about the bird strike protection and mitigation of their
rotorcraft compared to the RSPC continuum.
For rotorcraft manufacturers and modifiers:
Refer to this SAIB and contact an
FAA ACO if you want to pursue FAA approval of design modifications that
will allow your product to meet a higher level of bird strike
protection and mitigation on the RSPC continuum.
Operational Risk Mitigation Options
Reasonable flight planning and
in-flight decisions can keep the rotorcraft away from bird rich
environments and help prevent bird strikes. In the event a bird strike
does occur, personal equipment is an important consideration that
offers protection. Among the RBSWG’s operational recommendations were
the following.
Learn about the local bird
population and use it to plan and fly your route. Among the key
considerations are seasonal migratory times and concentration patterns
within your typical operating area.
Reduce airspeed when
practical. Three out of four bird strikes (77%) occur during airspeeds
greater than 80 knots. When operating rotorcraft in areas of high bird
concentrations, the likelihood of a damaging bird strike goes up as
airspeed increases. When operating in these areas, fly at 80 knots or
less, particularly when at lower altitudes.
Increase Altitude. Increase
altitude as quickly as possible and practical, when allowed by other
flight variables. There is a 32% decrease of bird strike likelihood for
every 1,000 feet gained above 500 feet AGL. Also, birds fly higher at
night, so you will have to increase your altitude even more than during
the day to try to avoid them.
Wear Personal Protective
Equipment (PPE). A helmet and visor, at least for the crew, should be
worn when practical. This is one of the simplest acts that can improve
safety in rotorcraft operations.
Reminder on Reporting Incidents
Report all wildlife strikes at https://wildlife.faa.gov/home.
For Further Information, Contact
Information on Design and Equipment Safety Mitigations and this SAIB contact:
Jorge Castillo, Manager, Strategic Policy Rotorcraft Section, Aircraft
Certification Service Policy and Innovation Division, 10101 Hillwood
Parkway, Fort Worth, Texas, 76177; phone: (817) 222-5110; fax: (817)
222-5961; email: Jorge.R.Castillo@faa.gov.
Information on Operational Mitigations contact:
Federal Aviation Administration (FAA) General Aviation and Commercial Division’s, Operations Group AFS-830 at 202-267-1100.