Air Transport

The investigation into the explosion of a Transmile Airlines Boeing 727-200 freighter's left wing during towing at Bangalore airport has found evidence of damaged wiring and electrical arcing within the wing's fuel tank, writes Darren Shannon.

According to the US National Transportation Safety Board (NTSB), which conducted an investigation between 24 May and 2 June, the aircraft involved in the 4 May incident was compliant with a US Federal Aviation Administration airworthiness directive requiring plastic sleeving for all wires, but that this "did not prove to be sufficient to prevent the Bangalore accident".

The incident occurred at Bangalore airport during a ground repositioning without passengers on board, and no injuries were reported.

The NTSB says that "the evidence indicates that an explosion in the left-wing fuel tank destroyed the structural integrity of the wing".

It adds: "Had this explosion occurred in flight, it would have resulted in the catastrophic failure of the wing and the aircraft would have crashed."

An on-scene NTSB-led team, which also travelled to the Malaysian carrier's home country, found evidence of damaged wiring, as well as electrical arcing within the left-wing fuel tank in an aluminium conduit tube that carries 115V AC power to the fuel pumps.

"This accident illustrates that ignition sources continue to exist and fuel tank explosions continue to occur in both wing and centre wing fuel tanks despite the corrective efforts of government regulators and industry," says the NTSB, which believes "the best protection against fuel tank explosions is to eliminate the flammable conditions inside the fuel tanks through design changes such as nitrogen-inerting systems".