Investigations into last week’s fuselage rupture and rapid decompression involving a Qantas Airways Boeing 747-400 have determined that parts from an oxygen cylinder blasted into the passenger cabin of the aircraft.
The aircraft’s emergency oxygen system is being looked at closely by Australian Transport Safety Bureau (ATSB) investigators as one of 13 cylinders located in the area of the 747 where the fuselage rupture occurred was found missing after the emergency landing in Manila.
Investigators have been looking into whether the cylinder exploded and as a result Qantas has been inspecting oxygen system bottles on its 29 other 747-400s.
“The ATSB can confirm that it appears that part of an oxygen cylinder and valve entered the passenger cabin and impacted the number 2 right door frame handle, thereby moving the handle part way towards the open position,” says the ATSB, which stops short of saying definitively that the cylinder exploded.
“However, the door handle mechanism has been sheared as it is designed to do if an attempt is made to open the door in flight, so the position of the door handle is not representative of the position of the door lock mechanism or the security of the door. The investigation team have confirmed that the door latches were still engaged. Additionally the door is of the plug-type that first needs to be pulled into the cabin, rotated 90° then pushed out to open. So there was never any danger of the door opening.”
The incident occurred on the morning of 25 July as the 747-400 was operating as flight QF30 from Hong Kong to Melbourne. At around 29,000ft (8,839m) part of the fuselage separated at the forward cargo hold on the right side of the aircraft which led to the rapid decompression. A rapid descent was carried out to 10,000ft, after which the aircraft made an emergency landing in Manila. No passengers or crew were injured.
The ATSB says the flight data recorder has now been decoded and an initial analysis shows the descent from 29,000ft to 10,000ft took around 5-1/2min, with an average descent rate of around 4,000ft per minute.
Some of the 346 passengers on board reported that their oxygen masks were not working. The ATSB says: “Inspection by the ATSB shows that 484 masks had deployed, that is, dropped from the ceiling. Of those, 418 had been activated by pulling on the mask to activate the flow of oxygen. Only a small number of masks appeared to have had the elastic retaining strap adjusted by the passengers. It also appears that a small number of masks did not deploy from the passenger modules. Investigations into this aspect of the accident are continuing.”
The ATSB also says in its update that the aircraft’s three instrument landing systems “were not available” for the landing at Manila, nor was its anti-skid system. But it says all main systems including engines and hydraulics were functioning normally, adding that the approach to Manila airport was conducted in visual conditions.
It goes on to say: “From the evidence gathered to date it appears that the flight crew have responded to and managed the emergency situation extremely well. It is apparent that they followed the procedures they have trained for in simulators, which ensured the best possible outcome for the aircraft, the passengers and crew.”
A preliminary factual report is likely to be released within around 30 days, says the ATSB, but “should the need for urgent safety action by any agency be identified, the ATSB will immediately notify the relevant agencies who are best placed to address the issue”.
Source: flightglobal.com's sister premium news site Air Transport Intelligence news
FLIGHT cutaway of Boeing 747
Source: Flight International
