National Transportation Safety Board
Office of Public Affairs
(Washington, DC) -- The National Transportation Safety Board (NTSB) is urging the Federal Aviation Administration (FAA) to tighten rules for aircraft repair stations, both in the United Sates and abroad, and to upgrade the sound quality of cockpit voice recorders in all airplanes.
The NTSB recommendations stem from the investigation of a ValuJet accident that occurred in Atlanta on June 8, 1995.
At a public meeting in Washington, DC, the NTSB concluded that the ValuJet DC-9 suffered an uncontained engine failure because a Turkish-based aviation maintenance and overhaul company did not properly inspect a 7th stage engine compressor disk. The engine was bought by ValuJet in 1994 from the Turk Hava Yollari repair station and placed on the DC-9. The failure to catch the detectable disk crack allowed the crack to grow to a length at which the disk ruptured, the Board concluded.
ValuJet flight 597, destined for Miami, Florida, was on its takeoff roll from Hartsfield Atlanta International Airport when the engine failed. Shrapnel from the failed engine penetrated the fuselage and the right engine main fuel line. A cabin fire erupted destroying the aircraft. One flight attendant was seriously injured from shrapnel and the fire. Another flight attendant and six passengers received minor injuries. None of the other 55 people on board were injured.
Contributing to the failure to detect the disk crack, the Safety Board determined, was that the Turkish repair station did not have an adequate recordkeeping system. It did not use "process sheets" to document step-by-step overhaul and inspection procedures.
As a result of its investigation, the Safety Board issued 12 recommendations to the FAA.
The NTSB urged the FAA to review the licenses and operations specifications of all repair stations to make sure that the authority to repair and overhaul aircraft and aircraft parts is clearly spelled out. The NTSB also called for more stringent recordkeeping requirements for all FAA-approved repair stations.
As part of its investigation, the NTSB also uncovered problems with flammable materials used in the aircraft's interior, flight attendant emergency training, the public address system and a lack of a clear cockpit voice recording from the DC-9 that burned.
To correct the shortcomings, the NTSB wants the FAA to require that all aircraft be equipped with upgraded cockpit voice recorders within two years. The Board said that all CVRs should include uninterrupted recordings from boom and mask microphones and headphones for each crewmember's position and from an area microphone. Those recordings should be made on dedicated CVR channels. The recommendation also urges the FAA to require that all audio signals received by hand-held microphones be recorded on the crewmember's CVR channel when keyed to the "on" position.
The NTSB also urged the FAA to require that older aircraft have their cabins upgraded with materials that meet current flammability standards when the aircraft's interior is replaced or when an aircraft is transferred from one carrier to another.
In addition, the NTSB wants the FAA to require that transport-category aircraft built before November 1990 be retrofitted with public address systems capable of operating on independent power sources; emphasize that FAA principal operations inspectors thoroughly review flight attendant training programs before approving them; require that all flight attendants have cockpit keys while on duty; and recommend that crew uniforms conform with FAA safety guidance for airline passenger attire.
The Safety Board's complete printed report, PB96-910403, will be available from the National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22161. The NTIS telephone number is (703) 487-4650.
Media contact: NTSB Office of Public Affairs
The National Transportation Safety Board (NTSB) is an independent federal agency charged with determining the probable cause
of transportation accidents, promoting transportation safety, and assisting victims of transportation accidents and their families.