Friday, March 06, 2009

Interim report on the July 2008 Qantas B-747 depressurization accident

QF30 - July 25, 2008The Australian Transport Safety Bureau (ATSB) has just released an Interim Factual Report regarding the sudden decompression in flight of a Qantas Boeing 747-400 on July 25, 2008. The accident happened during the cruise phase of Qantas Flight QF30, which was en route from Hong Kong to Melbourne. The flight diverted to Ninoy Aquino International Airport, Manila where it landed safely, with no serious injuries to the 365 people on board.

After the aircraft landed, a large rupture in the fuselage was discovered.  The ATSB's preliminary factual report about the accident, issued in August of 2008,  stated that one of the cylinders that supplied emergency oxygen to the passenger cabin had "sustained a failure that allowed a sudden and complete release of the pressurised contents," and that "damage to the aircraft's fuselage was consistent with being produced by the energy associated with that release of pressure" from the oxygen cylinder.

Today's interim report elaborated on damage to the aircraft and its systems, with many photos to illustrate. The report also provided detailed descriptions of the engineering tests carried out (and still underway) on components of the accident aircraft's emergency oxygen system, and on similar oxygen cylinders and fittings.

Among the points included in this lengthy interim report:
  • there was no evidence of an external explosive event or the use of explosive materials around the rupture area
  • no significant maintenance difficulties had been experienced with the passenger oxygen system prior to the accident
  • no anomalies in samples of the oxygen gas used to fill the cylinders were identified that would have contributed to this event
Regarding survivability issues, the ATSB said in a media release accompanying the report:
The investigation has determined that, despite the damage to the aircraft's passenger oxygen system caused by the oxygen cylinder failure, the system would have continued to operate for approximately 65 minutes following the depressurisation event. Passenger oxygen was only required for about 5 ½ minutes during the period between the depressurisation event and when the aircraft reached an altitude of 10,000 ft.
The ATSB expects to issue a final report on this accident investigation by the end of 2009.

Here is the link to the report: ATSB Transport Safety Report: Aviation Occurrence Investigation AO-2008-053, Interim Factual - 62-page 'pdf' file

[Photo Source]