The bulletin
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SPECIAL AIRWORTHINESS
INFORMATION BULLETIN
Aircraft Certification Service Washington, DC
U.S. Department of Transportation Federal Aviation Administration
NM-06-29 February 7, 2006 http://www.faa.gov/aircraft/safety/alerts/SAIB This is information only. Recommendations aren’t mandatory.
Introduction
This Special Airworthiness Information Bulletin alerts you, owners and operators of airplanes with pilot and copilot seats equipped with unguarded rotary seat belt buckles. These buckles have the potential of being activated unintentionally, releasing the seat belts attached to them. These buckles may be installed on, but are not limited to the aircraft listed in Table 1.
Background
We have researched the design of pilot and copilot rotary seat belt buckles and have determined there is a potential for the rotary buckle to be activated unintentionally, releasing the seat belts attached to them.
The National Transportation Safety Board (NTSB) issued recommendation A-03-057 after investigating the January 8, 2003, crash of a Raytheon (Beechcraft) 1900D, shortly after takeoff from Charlotte-Douglas International Airport.
NTSB Recommendation A-03-057:
“Identify all airplanes equipped with unguarded flight crewmember rotary seatbelt buckles and require replacement with guarded buckles that cannot be inadvertently unlatched”
The investigation determined that the captain’s rotary seat belt buckle became unbuckled during the accident. A Beech 1900 pilot also told NTSB investigators that he had previously experienced the uncommanded (unintentional) release of a rotary buckle. The buckle released when the pilot pulled the control yoke aft and contacted the vanes of the rotary buckle. The Air Line Pilots Association (ALPA) reported it was aware of five similar events.
NTSB staff conducted post-accident ground tests on a Beech 1900D airplane during which a person about the same height as the captain, seated in a crewmember seat, pulled aft on the yoke and rotated the yoke. The tests showed that it was possible for the yoke to contact the rotary seat belt buckle vane and rotate the seat belt buckle. This series of events is consistent with information on the accident flight’s digital flight data recorder.
2 Recommendation
We recommend you conduct an evaluation of your installations by performing the procedure described below. A test pilot developed this procedure during flight test evaluations of an airplane. The pilot inadvertently unlatched the buckle during some testing and then showed that he could consistently unlatch the buckle by performing the actions described in the procedure.
Procedure
Seat a person approximately 5 feet tall (this height represents approximately 5% females in the US) in the flight crew seat, with the seat placed in the most forward location. Have the person pull the control yoke back to the most aft position, rotate the yoke fully to the right and then to the left. Test observers should check if the yoke engages the fins of the seat belt buckle.
If any part or feature of the yoke including, but not limited to the map/chart holder, engages the fins on the buckle, then we recommend you replace the buckle with a guarded buckle.
It isn’t necessary for the buckle to disengage for the test to be considered a failure.
NOTE: This SAIB only affects pilot and copilot seats equipped with unguarded buckles on airplanes with control yokes.
Airplanes equipped with stick and side stick controls are excluded. Movement of these types of controls doesn’t create a rotary movement that could engage the fins of an unguarded rotary buckle.
For Further Information Contact
Alan Sinclair, Aerospace Engineer, FAA Transport Airplane Directorate, Standards Staff, Airframe/Cabin Safety Branch, 1601 Lind Ave. SW, Renton, Washington 98055;
phone: (425) 227-2195; fax: (425) 227-1149;
email: alan.sinclair@faa.gov
3 TABLE 1 - AFFECTED AIRCRAFT
ATR42 ATR72 Aerospatiale (S.N.I.A.)
SN-601 "Corvette" ATP BAe 146 BAE Systems Limited Jetstream 4100 Series 707 717 727 737 747 757 767 Boeing 777 Bombardier Aerospace Inc.
BD-100-1A10 (Challenger) BD-700-1A10 (Global Express) CL-600-1A11 (CL-600 series) CL-600-2C10 (CRJ 700 series) CL-600-2D24 (CRJ 900 series) DHC-3 DHC-4 DHC-6 Bombardier Inc.
DHC-7 British Aerospace Airbus Limited BAC 1-11 500 550 S550 560 560XL Cessna Aircraft Company 750 Fan Jet Falcon Mystere-Falcon 20 Mystere-Falcon 200 Mystere-Falcon 50 Dassault- Aviation Mystere-Falcon 900
Falcon 900EX Falcon 2000 Dassault- Falcon 2000EX EMB-120 EMB-135 Embraer EMB-145 328-100 Fairchild Dornier GmbH 328-300 F27 Fokker Services F.28 G-IV GV Gulfstream Aerospace Corporation GV-SP Astra Gulfstream Aerospace LP (Israel Aircraft Industries, Ltd.)
Galaxy Israel Aircraft Industries, Ltd.
1121 24 25 31 35 45 55 Learjet 60 Lockheed Martin Corporation L-1011 DC-8 DC-9 DC-10 McDonnell Douglas MD-11 BAe.125 BH.125 DH.125 HS.125 Raytheon 1900D SAAB 2000 Saab Aircraft AB SAAB 340 SD3-30 Short Brothers PLC SD3-60