Fuel Tank Blamed for Thai Airways Fire

An explosion that destroyed a Boeing 737 last month on the ground in Bangkok was caused by the same problem that downed TWA Flight 800 off the coast of New York in 1996, according to preliminary evidence.

A Thai Airways International 737 burst into flames March 3. Investigators found no evidence of a bomb and traced the blast to the center fuel tank, the U.S. National Transportation Safety Board ((NTSB) said Wednesday. The NTSB is assisting Thai authorities because of the board's expertise. A flight attendant aboard the jet died.

The jet's cockpit voice recorder captured the sounds of the explosion. The NTSB said those sounds "are similar" to noises recorded in the explosion of the center fuel tank on a Philippine Airlines 737 in 1990.

Last year, the NTSB ruled that TWA's 747 broke apart from a center tank explosion. All 230 people aboard died.

In that explosion, the NTSB suspected frayed wiring or one of several other sources led to a spark in the hot fuel vapors. The safety board has recommended steps to reduce the chances that tanks can explode.

For example, the NTSB said that air conditioning systems be switched off on the ground. The air conditioning units emit heat, which can cause the fuel in the tank to vaporize and become explosive. Last May, Boeing also warned its customers in a letter to switch off air conditioning on the ground.

In both the TWA and Thai accidents, air conditioning systems adjacent to the center tank in the jets were turned on.

The NTSB said the Thai jet's air conditioning system had been operating for about 40 minutes on the ground. The temperature was in the 90s.

It could not be learned why Thai Airways had not heeded Boeing's advice.

Safety advocates say they worry that not all U.S. carriers have been following Boeing's advice, which is not required under federal rules.






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