Qantas 744 Depressurisation
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Ozthai 999
That brings us back to my theory (Expressed weeks back on this very forum) http://www.pprune.org/rumours-news/3...ost4289735That If there was a fastener of incorrect length fitted to that fairing and the tail of the fastener had damaged the pressure hull causing a weak spot....... Would the subsequent failiure cause the O2 cylinder to disintergate aswell? and what damage would that cause?
Rgds Dr I
That brings us back to my theory (Expressed weeks back on this very forum) http://www.pprune.org/rumours-news/3...ost4289735That If there was a fastener of incorrect length fitted to that fairing and the tail of the fastener had damaged the pressure hull causing a weak spot....... Would the subsequent failiure cause the O2 cylinder to disintergate aswell? and what damage would that cause?
Rgds Dr I
I believe that the oxygen bottle is pretty impervious to extremely rough handling, pressure changes etc. The most I could see is the fittings at the top failing.
However since I still have not seen confirmed facts that the bottle itself exploded, all theories are still guesses
However since I still have not seen confirmed facts that the bottle itself exploded, all theories are still guesses
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Is there any possibilty that the hull could have failed first, (for some unknown reason). Subsequently the rapid decompression of the cargo hold caused an extreme pressure difference between the bottle and ambiant pressure then the faulty fitting blew off the bottle and the bottle torpedoed out increasing the hull demage.
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Is there any possibilty that the hull could have failed first, (for some unknown reason). Subsequently the rapid decompression of the cargo hold caused an extreme pressure difference between the bottle and ambiant pressure then the faulty fitting blew off the bottle and the bottle torpedoed out increasing the hull demage.
CASA have just released an urgent AD for improved inspections of lap joints in the area of the wing/fuselage join (eg: right where this occurred).
CASA have just released an urgent AD for improved inspections of lap joints in the area of the wing/fuselage join (eg: right where this occurred).
It seems that if this is not unique to Qantas than the FAA as the regulator of the certicate holder is bound to verify and reissue a broader AD .
I'm not sure yet if this is a clue in this thread.
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The cabin crew in the first class section reported seeing something akin to a blast wave of dust and condensation coming forward from the area of the hole at R2, which then reversed itself as the air was sucked out of the hole.
The clear inference is that the bottle exploded first, causing the hole which then caused the depressurisation.
The clear inference is that the bottle exploded first, causing the hole which then caused the depressurisation.
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Perhaps somebody can post a copy of the words that CASA used to justify the AD in order to see if there is any linkage with this thread discussion.
Here's the text:
Applicability:
Model 747-100, -100B, -100B SUD, -200B, -200C, -200F, -300, -400, 747SR, and 747SP series airplanes, certificated in any category, as identified in Boeing Alert Service Bulletin 747-53A2312, Revision 3, dated February 8, 2007 or later FAA approved revision.
Requirement:
Action in accordance with the technical requirements of FAA AD 2008-16-14 Amdt 39-15632.
Note:
Boeing Alert Service Bulletin (ASB) 747-53A2312 Revision 3 or later FAA approved revision refers.
Compliance:
As specified in the requirement document.
This Amendment becomes effective on 17 September 2008.
Background:
This Directive was prompted by reports of cracking in the stringer 34 lap joint near the interface with the wing-to-body fairing. This condition, if not corrected, could result in an in-flight depressurisation of the aircraft.
Amendment 1 reduced the number of aircraft to be inspected and widened the inspection area to include all lap splice upper rows under the wing-to-body fairing.
Amendment 2 allowed use of ASB 747-53A2312 Revision 3 as an alternative method of compliance with the requirements of FAA AD 94-15-06.
Amendment 3 is issued to change the requirement document. FAA AD 94-15-06 Amdt 39-8977 is superseded by FAA AD 2008-16-14 Amdt 39-15632. This results in a change to the High Frequency Eddy Current inspection method due to possible faulty results when inspecting Alodine-coated rivets; adds an additional one time inspection for cracking; and terminates the adjusting factor for the inspection compliance times based on cabin differential pressure.
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And here's the URL (posted separately in case it's the URL that's causing the moderator flag):
http://www.casa.gov.au/airworth/airw...7/b747-128.pdf
http://www.casa.gov.au/airworth/airw...7/b747-128.pdf
The Reverend
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This confirms my suspicions of the pressure hull breach being caused by an exploding oxygen cylinder. Still does not explain the fact that the overpressure valves were activated?
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I think a couple of cubic feet of oxy turning into many times that in an instant is enough to pop the Op valves.The rate of expansion would imho exceed the rate at which the entire hull could absorb or release the pressure.The hull breach itself may have come very shortly after the initial explosion with parts of the cylinder likely belting around violently.Even if the hull went straight away the instantaneous increase in pressure would likely pop the valves too being the weak point in an OP situation and relatively nearby the source.
Heard an interesting rumour regarding the reason why it went off.Pretty conclusive if its a fact.And not surprising it did go off..... if true.
Heard an interesting rumour regarding the reason why it went off.Pretty conclusive if its a fact.And not surprising it did go off..... if true.
Thanks for the AD link.
Personaly I don't see a direct link to this thread.
It appears that Boeing simply issued a modification to an existing service bulletin and the CAA in an abundance of caution in their current fishbowl raised this to an AD.
No where does it cite new information based on formal investigative findings.
BTW Hotdog
The judges have decided that it is premature to award you a gold medal for the best theory about what caused this incident
Personaly I don't see a direct link to this thread.
It appears that Boeing simply issued a modification to an existing service bulletin and the CAA in an abundance of caution in their current fishbowl raised this to an AD.
No where does it cite new information based on formal investigative findings.
BTW Hotdog
The judges have decided that it is premature to award you a gold medal for the best theory about what caused this incident
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Heard an interesting rumour regarding the reason why it went off.Pretty conclusive if its a fact. And not surprising it did go off..... if true.
As a complete aside- John Coates, the head of Australian Olympic Committee, has conceded publicly that the Poms might edge out the Aussies. "Not bad for a country that has no swimming pools and very little soap." Pom
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It appears that Boeing simply issued a modification to an existing service bulletin and the CAA in an abundance of caution in their current fishbowl raised this to an AD.
No where does it cite new information based on formal investigative findings.
No where does it cite new information based on formal investigative findings.
True that - but it is interesting that it's the area of the blow out, thus my reason for bringing it up
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Iomapaseo - The CAA encouraged by AAIB often found it necessary to raise ADs on US products when the FAA approach seemed insufficiently robust.
But the glass bowl residents in this case are CASA, Aussies, nothing to do with the Brits.
But the glass bowl residents in this case are CASA, Aussies, nothing to do with the Brits.
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comment from crikey.com.au reporting on the Qantas AGM today
"However he did say all of the 737s in question were back in service, and that the damage to the 747-400 that made an emergency diversion to Manila last month would cost less than $10 million to repair and would return to service in October. "
"However he did say all of the 737s in question were back in service, and that the damage to the 747-400 that made an emergency diversion to Manila last month would cost less than $10 million to repair and would return to service in October. "
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to forget
The rumour was, allegedly the bottle was dropped onto concrete during servicing elsewhere and refitted.
The rumour was, allegedly the bottle was dropped onto concrete during servicing elsewhere and refitted.
As a complete aside- John Coates, the head of Australian Olympic Committee, has conceded publicly that the Poms might edge out the Aussies. "Not bad for a country that has no swimming pools and very little soap." Pom
Maybe it should be remembered that the australians ancestors were handpicked by the best english judges?? lol
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to lomapaseo
That of course depends from what height the cylinder was dropped.
From what I hear it was not insignificant.
Anyway just a strong rumour and subject to confirmation.
From what I hear it was not insignificant.
Anyway just a strong rumour and subject to confirmation.