Aircraft
Certification Service Washington, DC U.S. Department of Transportation Federal Aviation Administration
2023-08
August 1, 2023
This is information only. Recommendations
aren’t mandatory.
Introduction
This Special Airworthiness Information Bulletin recommends the owners
and operators of transport airplanes install safety enhancing features
for certain occupant seating positions. Current FAA guidance allows for
seat configurations with large setbacks that can allow an occupant to
freely flail forward in an accident. However, this condition will not
meet updated methods of compliance with Title 14, Code of Federal
Regulations (14 CFR) 25.785 which specifies that occupants not suffer
“serious injury in an emergency landing” (including 16g forward
deceleration), when making proper use of the safety features provided.
The FAA is in process of changing guidance to no longer accept these
seating configurations unless the torso is supported by some safety
enhancing feature. Until this guidance is published, the FAA is
promoting voluntary adoption of installing safety enhancing features
such as airbags and shoulder harnesses. Installing the features in
these seat locations will enhance passenger safety in the event of an
accident. These features are already required in many general aviation
aircraft and helicopters, and widely used by others seeking increased
safety.
At this time, the airworthiness concern is not an unsafe condition that
would warrant airworthiness directive (AD) action under 14 CFR part 39.
Background
The potential for spinal injuries during a forward impact was not
considered likely until recent Post Mortem Human Subject (PMHS)
research tests uncovered spine injuries when a lap-belt-restrained
occupant experiences 14 CFR 25.562 emergency landing loads (16g
forward).
FAA research report “Comparison of standard and Y-belt aircraft passenger restraints in frontal impacts with PMHS and ATD”1
identifies potentially serious injuries resulting from excessive body
flail in seat configurations with large setbacks, or row-to-row seat
large pitch (i.e., those that permit unrestrained upper torso forward
flail, or free flail, where there is no head contact during an
emergency landing) and lap belt-only restraints. The data was presented
at The Eighth Triennial International Fire & Cabin Safety Research
Conference.2 The unrestrained upper torso flail injury
potential is supported by accident data, including from the Asiana 214
accident in 2013 and Turkish 1951 accident in 2009. Occupants with free
flail suffered spinal injury, while occupants whose torso was supported
by seatback contact did not.
As a result of the research and accident data, the FAA is revising the
advisory circular (AC) 25.562-1b guidance to remove the large setback
allowance for seat installations incorporating lap belt restraints as
an acceptable method of compliance. Additionally, the FAA is cancelling
Policy ANM-115-05-14, which supports a means of compliance to
§§ 25.562 and 25.785 by establishing large seat installation
setbacks.
Recommendations
The FAA is promoting voluntary adoption of installing safety enhancing
features such as airbags and shoulder harnesses for owners and
operators of transport aircraft for seating configurations with large
setbacks with lap belt only restraints at the next available
opportunity.
For Further Information Contact
Patrick Farina, Aerospace Engineer, 3960 Paramount Blvd Ste 100,
Lakewood, CA 90712, United States; phone: (562) 627-6721; fax: (562)
627-5210; e mail: Patrick.Farina@faa.gov.
1 Report published in proceedings of the 53rd Annual Rocky
Mountain Bioengineering Symposium, RMBS 2016 & 53rd International
ISA Biomedical Sciences Instrumentation Symposium 2016. Available from
the internet at https://www.proceedings.com/31943.html
Abstract available on the internet at
https://www.fire.tc.faa.gov/2016Conference/files/Crash_Dynamics_III/HummFrontRowOccupant/HummFrontRowOccupantAbs.pdf 2 Available on the internet at
https://www.fire.tc.faa.gov/2016Conference/files/Crash_Dynamics_III/HummFrontRowOccupant/HummFrontRowOccupantPres.pdf