The Australian Transport Safety Bureau (ATSB) has issued its preliminary factual report into an incident on 25 July in which the fuselage of a Qantas Boeing 747-400 was ruptured by an oxygen cylinder on-board that exploded.

It says because "the failed cylinder was not recovered, the ATSB is currently working with the aircraft manufacturer, other aircraft operators and the oxygen cylinder manufacturer to obtain samples of cylinders from the same manufacturing batch as the failed item".

The missing cylinder was one of a batch of 94 cylinders manufactured in February 1996 and records show it was fitted to the aircraft on 14 June this year, it adds.

In the factual report, the ATSB has an advisory safety notice recommending that "all organisations performing inspection, testing, maintenance and repair activities on aviation oxygen cylinders, to note the circumstances detailed in this preliminary report with a view to ensuring all relevant procedures, equipment, techniques and personnel qualifications satisfy the applicable regulatory requirements and established engineering best practices."

It also makes a similar recommendation to air transport operators.

Qantas - in agreement with Australia's Civil Aviation Safety Authority (CASA) - "commenced a fleet wide programme of detailed visual inspections of its Boeing 747 oxygen system installations" and those inspections were completed on 1 August, it adds.

The ATSB says the ongoing engineering investigation into the apparent oxygen cylinder failure will focus on - but not be limited to - the:  cylinder design, manufacturing methods and type testing procedures; manufacturing quality control processes; modes and mechanisms of cylinder failure; historical oxygen and pressurised cylinder failure experienced; cylinder degradation systems; the adequacy and efficacy of inspection; maintenance and repair processes, procedures and equipment prescribed by the manufacturer and implemented by maintenance organisations; and cylinder filling processes and procedures.


Even though the cylinder at the centre of the investigation was made in 1996, the aircraft - local registration VH-OJK - was manufactured in 1991.

The ATSB says at 09:22 local time on 25 July the aircraft departed Hong Kong for Melbourne and the incident occurred at 10:17 local time.

It says the aircraft - with 365 people on board - was at 29,000ft when "a loud bang was heard by passengers and crew, followed by rapid depressurisation of the cabin."

"The oxygen masks dropped from the overhead compartments shortly afterward" and "after donning their own oxygen masks, the flight crew ...commenced a descent to a lower altitude" so supplemental oxygen would no longer be required.

"After levelling the aircraft at 10,000ft the flight crew diverted to Ninoy Aquino International Airport, Manila."

Once the aircraft landed, a visual inspection "revealed an inverted T-shaped rupture in the lower right size of the fuselage immediately beneath the wing leading edge-to-fuselage transition fairing which had been lost during the event".

It says the rupture was approximately 2m along the length of the aircraft and 1.5 metres vertically.

"After clearing the baggage and cargo from the forward aircraft hold it was evident that one passenger oxygen cylinder, number-4 from a bank of seven along the right side of the cargo hold, had sustained a sudden failure and forceful discharge of the contents into the aircraft hold, rupturing the fuselage."

It says "the cylinder had been propelled upward by the force of the discharge, puncturing the cabin floor and entering the cabin adjacent to the second main door."

The cylinder then "impacted the door frame, door handle and overhead panelling before falling through the cabin floor and exiting the aircraft through the ruptured fuselage".

It also says "both right side first officer's aileron control cables routed along the right side of the fuselage above the passenger oxygen cylinders had been fractured during the rupture event."

Even though the oxygen cylinder went through the cabin floor, the ATSB says no one on board was injured.

Qantas boss Geoff Dixon says in a separate statement today that "our own investigation agrees with the ATSB's preliminary conclusions".

He says Qantas is now having the aircraft repaired at Lufthansa Technik in Manila and the aircraft will be back in service in November at a cost of less than A$10 million ($8.6 million).

Source: Air Transport Intelligence news