The Federal Aviation Administration will propose modifications in the takeoff alarm systems on virtually all United States commercial jetliners to guard against an electrical short that could keep the alarm from sounding, officials say. The directive, which would apply to more than 3,700 commercial jets, is expected to be announced shortly. Airlines would have until February to comment on the proposal, which the FAA would then be expected to make final.
One FAA official said the changes in the alarm systems are not expected to interrupt normal airline service because they likely will be required during routine maintenance.
The crash on Aug. 16, 1987, of Northwest Airlines Flight 255 during a takeoff from Detroit's Metro International Airport was blamed on the failure of the flight crew to set the plane's wing flaps properly for takeoff. The crashed killed 156 people.
Investigators are also examining the possibility of an improper flap setting in the crash of a Delta Air Lines jet at Dallas last August in which 14 of the 108 people aboard were killed. There was no sounding of the takeoff alarm system in that aircraft either.
The Detroit crash involved a McDonnell Douglas MD-80, while the crash in Texas involved a Boeing 727.
According to sources, the FAA directive will cover virtually all commercial jetliners including those produced by the Boeing Company, McDonnell Douglas, and Airbus Industrie, the European aircraft manufacturing consortium.