NTSB investigating reported fuel-tank explosion on Boeing 727 in India

The National Transportation Safety Board (NTSB) is sending a team of investigators to Bangalore, India, to assist in the investigation of a reported wing fuel-tank explosion on a Transmile Airlines Boeing 727-200. Transmile is a Malayasian air-cargo company. The incident occurred May 4 while the airplane was on the ground in Bangalore. There were no passengers and no one was injured.

The investigation comes just ahead of the 10th anniversary of the loss of TWA-800 off the coast of New York state, with the deaths of all 230 people aboard that Boeing 747. The plane was brought down by a mid-air explosion inside the center fuel tank — not the wing tank. The cause of the ignition inside the tank was never identified. Since then, prevention of fuel-tank explosions has been an intense focus at the NTSB and at the Federal Aviation Administration (FAA).

"The tragic TWA 800 accident in 1996 highlighted the vulnerability of transport aircraft fuel tanks," said NTSB acting chairman Mark Rosenker in a statement today. "A decade later, the issue remains a major concern of the Safety Board and is on our Most Wanted List of Safety Improvements. I am hopeful what is learned in this investigation may provide added impetus for a resolution of this problem without further delay."

After a series of safety studies following the TWA-800 disaster, the FAA proposed a rule that would mandate fuel-tank "flammability reduction systems" on all commercial aircraft that have a center fuel tank and require retrofits on in-service aircraft. Center tanks are heated and more vulnerable to explosions than wing tanks.

The most likely way of meeting the mandated requirement is the fitting of inerting systems, which work by releasing non-flammable nitrogen gas into the space in the tank as the fuel level goes down in flight.

Boeing is currently testing an inerting system and expects in about six months to have it certified and ready to install on all new jets coming off its assembly lines.

The comment period for the FAA proposal ended earlier this month. The Air Transport Association, representing the airlines, submitted comments opposing the rule as not cost effective. The required retrofits on the existing commercial fleet, which would be paid for by the airlines, would be very costly at a time when airlines are losing billions of dollars.

If implemented, the new rule would apply to all current Boeing jet models. However, because the older 727 doesn't have a center fuel tank, the rule in any case would not apply to the jet involved in the incident in Bangalore.