Boeing issues 737 safety warning

One person was killed in the explosion that happened less than an hour before takeoff

WASHINGTON (CNN) -- Operators of Boeing 737 airliners should not operate fuel boost pumps on almost-empty fuel tanks, the manufacturer Thursday told carriers worldwide.

The warning is based upon a conclusion that a Thai Airways International jet that exploded last month was using a pump in an empty tank.

Investigators and Boeing Co. officials say the fuel pump has not been identified as a cause of the March 3 blast, which occurred as the plane was sitting at a gate at a Bangkok airport. They note that Boeing 737 manuals already tell pilots to turn off pumps when they are not being used.

But Boeing said it decided to reiterate its guidance to airlines after learning that the Thai Airways jet had its pump on at the time of the explosion.

"It may have absolutely nothing to do with this accident but we don't know," Boeing spokesman Tim Neale said. The "message to operators" is "intended to emphasize our recommendation which is in the manual," Neale said.

The message, sent to Boeing 737 operators worldwide, tells pilots to turn off the fuel pump if there is less than 1,000 pounds of fuel in the tank.

A Federal Aviation Administration spokeswoman said the agency is reviewing the Boeing message and is considering issuing an airworthiness directive -- which carries the force of law -- in the matter.

"We're looking at this now, but we haven't made a decision yet," spokeswoman Alison Duquette said.

Boeing's Neale said fuel pumps go through extensive testing before they are certified for use in aircraft. As part of that process, technicians make sure they can be operated safely in empty or partially filled tanks, he said.

"We didn't find that (the pump) is a safety hazard," he said. The message to Boeing operators "just seemed like the prudent thing to do."

Neale said Boeing also intends to rewrite 737 flight manuals to emphasis proper pump usage.

The Thai Airways international plane -- a 9-year-old Boeing 737-400 -- exploded as it was sitting at a gate at Don Muang International Airport in Bangkok. A flight attendant aboard the plane was killed and seven people were injured.

The plane exploded just 35 minutes before it was to depart with the prime minister of Thailand, prompting speculation that a bomb had been planted in an attempt to assassinate him. But investigators say initial tests have shown no signs of a bomb.

Investigators are also looking at any role heat-generating air conditioning units may have played in the blast. The cooling units, located directly under the center wing fuel tank, had been operating for at least 40 minutes while the plane was at the airport gate.

Air conditioners were deemed a "contributing factor" to the explosion of TWA flight 800, which exploded off the coast of Long Island, New York, in the summer of 1996. All 230 people aboard died.

Center wing fuel tank suspected in Thai Airways explosion
April 11, 2001
Thai leader uncertain if explosive caused plane fire
March 4, 2001
Thai jet blaze may have been sabotage
March 3, 2001

FAA
Thai Airways International
Boeing 737 Family
National Transportation Safety Board

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