Oxygen bottle blamed for Qantas plane explosion

CANBERRA (Reuters) - Australian air safety investigators on Friday blamed an oxygen bottle for a mid-air explosion which blew a minivan-size hole in the side of Qantas 747, but said they don't know why the bottle blew up.

The Qantas 747-400 suffered a sudden loss of cabin pressure during a flight from Hong Kong to Melbourne on July 25, forcing the aircraft to make an emergency descent before diverting to the Philippines, where it landed safely in Manila.

Australian Transport Safety Bureau (ATSB) director Julian Walsh said it was clear one of the plane's cargo hold oxygen bottles had ruptured, blowing a hole in the fuselage and sending the bottle up through the passenger cabin floor.

"It happened very quickly," Walsh told reporters as he released a preliminary report on the ATSB's investigations.

"The oxygen bottle went from the base of the aircraft, to the ceiling of the first-floor cabin," he said, adding it hit the handle of the cabin door on the way.

But the preliminary report into the incident gave no explanation on why the oxygen cylinder, the fourth in a line of seven cylinders along the right side of the cargo hold, failed under pressure.

The tank was part of a batch of 94 cylinders made in February 1996, and had undergone regular three-yearly checks. It was serviced and refitted to the plane six weeks before it failed.

The resulting explosion tore a 2-metre by 1.5 meter hole in the plane's fuselage, destroying cabling and disabling the plane's instrument landing system, one of the flight management computers, and the anti-skid brake system, the report said.

The pilot landed the plane manually, with help from air traffic controllers in Manila, where all 346 passengers and 19 crew disembarked safely. (Reporting by James Grubel; Editing by Valerie Lee)