Qantas 744 Depressurisation
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Attn. Rottenray
‘What if the bottle blew in the direction of the pressure vessel (fuselage) and caused a failure which allowed the concentration of oxygen to exit? The fluid dynamics work, from a scientific point of view. Large pressure wave, failure, and immediate flow and escape aided by pressure within the vessel. Any comments?’
Yes, I agree entirely. All we need is to verify an earlier story that O2 bottle débris was found in the hold.
[Later] Oops — looks as though it has been verified. Could we be facing the end of the thread? Rainboe will have to take his self-importance elsewhere.
Yes, I agree entirely. All we need is to verify an earlier story that O2 bottle débris was found in the hold.
[Later] Oops — looks as though it has been verified. Could we be facing the end of the thread? Rainboe will have to take his self-importance elsewhere.
Last edited by Vertiginous; 28th Jul 2008 at 13:18.
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"ILS out? is the glideslope antenna in the vicinity of the damage?"
Nope. Glideslope & Localizer antenna are located under the weather radar radome and embedded in the Nose Landing Gear doors.
Nope. Glideslope & Localizer antenna are located under the weather radar radome and embedded in the Nose Landing Gear doors.
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Nope. Glideslope & Localizer antenna are located under the weather radar radome and embedded in the Nose Landing Gear doors.
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I believe the co-ax would run from the nose area to the recievers in the MEC... not really anywhere near the damaged area, but now I wonder if some shrapnel from the cylinder actually penetrated the MEC, causing some damage there? We shall see...
Not familiar with the 747, but on the 737-700 I fly (and don't ask me why....) I paid particular attention to the equivalent fairings on my last walk-round. They're placarded with the words: 'Caution: ensure fasteners used are of correct length'.
If a lazy engineer jammed in a fastener that was too long because it was a long walk to get the correct replacement from stores, is it possible that it could have been left contacting the skin beneath. Then with abrasion over a period of time, could a weak spot have developed that eventually failed explosively under pressurisation, ripping a big hole?
If a lazy engineer jammed in a fastener that was too long because it was a long walk to get the correct replacement from stores, is it possible that it could have been left contacting the skin beneath. Then with abrasion over a period of time, could a weak spot have developed that eventually failed explosively under pressurisation, ripping a big hole?
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Troy, it could and to some smaller extent has. The thing is, most lazy engineers would not be seen within 100 miles of putting fairings of that size back on. Its the young keen wanabe pilot ones that generally do that sort of thing!
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‘So why did the lower sections all seem to separate along a rivet line, while the rest was random tearing?’
It takes less force to separate a riveted lap seam than to rip a panel. In other words, if a panel is ripped, this was achieved with a large amount of energy.
It takes less force to separate a riveted lap seam than to rip a panel. In other words, if a panel is ripped, this was achieved with a large amount of energy.
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O2 tank valve found in cabin ....
Can somebody help me out here.
Does the missing tank lay horrizontal or vertical when secured in place?
(just trying to figure out how a valve hits a floor above)
In the famous picture of the big hole in the fuselage in this thread could one of out artists sketch in the axis of the fuel tank relative to the rips and tears?
From my understanding of the kinematics the light weight valve if broken cleanly off would accelerate faster than the rest of the bottle. I would however only expect a steady force for several seconds on the rest of the tank against its supporting structure.
Of course the extreme rarity of an exploding bottle (not just losing a valve stem) in a confined area is not within my experience bank. (some of our military members may have something to say here through)
Does the missing tank lay horrizontal or vertical when secured in place?
(just trying to figure out how a valve hits a floor above)
In the famous picture of the big hole in the fuselage in this thread could one of out artists sketch in the axis of the fuel tank relative to the rips and tears?
From my understanding of the kinematics the light weight valve if broken cleanly off would accelerate faster than the rest of the bottle. I would however only expect a steady force for several seconds on the rest of the tank against its supporting structure.
Of course the extreme rarity of an exploding bottle (not just losing a valve stem) in a confined area is not within my experience bank. (some of our military members may have something to say here through)
Thank you Beachfront. From the article:
"A Qantas spokeswoman confirmed that flight QF692 "performed a routine air-turn back … due to an indication that one of their landing gear doors failed to retract".
"The aircraft (a Boeing 737-800) landed without incident and all passengers were accommodated on other flights. There was no safety risk at any time," she said."
Fortunately there appear to have been no cabin crew working in that galley at the time and who might differ on the subject of "safety risk". They might even wonder a bit at the spokeswoman's aircraft identification skills.
But what a shame it's all been revealed; this thread could have gone on for at least another twenty pages!
"A Qantas spokeswoman confirmed that flight QF692 "performed a routine air-turn back … due to an indication that one of their landing gear doors failed to retract".
"The aircraft (a Boeing 737-800) landed without incident and all passengers were accommodated on other flights. There was no safety risk at any time," she said."
Fortunately there appear to have been no cabin crew working in that galley at the time and who might differ on the subject of "safety risk". They might even wonder a bit at the spokeswoman's aircraft identification skills.
But what a shame it's all been revealed; this thread could have gone on for at least another twenty pages!
Second Law
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llondel re 529
Correct and you beat me to it sir.
(This thread takes some keeping up with.....)
Expanding a gas adiabatically leads to a fall in temperature, the bigger the presure gradient the bigger the (Joule/Tomson/Kelvin) effect.
And quite correct about the quality of the data being added too, impressive.
CW
Correct and you beat me to it sir.
(This thread takes some keeping up with.....)
Expanding a gas adiabatically leads to a fall in temperature, the bigger the presure gradient the bigger the (Joule/Tomson/Kelvin) effect.
And quite correct about the quality of the data being added too, impressive.
CW
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OK if we have established that the oxygen cylinder did fail
[understand not fragments of cylinder but parts from the regulator] then what was the reason for its failure. a reasonably new bottle
it couldnt be due to internal corrosion or pitting.... ????.
It would have to be due to two other alternatives
1. incorrectly fitted regulator..... but why fail after 6 months ????
2. over pressure... but how could this occur?
1. incorrectly fitted regulator... for a number of weeks now OJK had been flying around with an mel requirement to physically check oxygen pressure every transit....was it leaking??? possibly
The total pressure of all cylinders is summed to give a single reading in cockpit and a single low pressure would not be indicated there the only way to know if the cylinder was low in pressure is when the physical check is done.
2. If this bottle had shown a history of continually under-reading then it would have been replaced earlier due to the requirement of checking every transit for at least 2 weeks. The question of over pressure would only be acceptable if serviced outside of Australia. The servicing procedure here is to service from one single service point and all bottles are then equal in pressure. The procedure adopted by most overseas MRO's is to remove the low bottle/s and service them in a clean environment, which has its merits... but one of the negatives is you you don't have the uniform pressures, and one or more bottles could be over pressure.
Qantas have a standard procedure which requires those persons servicing oxy bottles to complete appropriate training.. we hope that other agents that work on our aircraft are also trained.
piece of cylinder found embedded
6 months
It would have to be due to two other alternatives
1. incorrectly fitted regulator..... but why fail after 6 months ????
2. over pressure... but how could this occur?
1. incorrectly fitted regulator... for a number of weeks now OJK had been flying around with an mel requirement to physically check oxygen pressure every transit....was it leaking??? possibly
The total pressure of all cylinders is summed to give a single reading in cockpit and a single low pressure would not be indicated there the only way to know if the cylinder was low in pressure is when the physical check is done.
2. If this bottle had shown a history of continually under-reading then it would have been replaced earlier due to the requirement of checking every transit for at least 2 weeks. The question of over pressure would only be acceptable if serviced outside of Australia. The servicing procedure here is to service from one single service point and all bottles are then equal in pressure. The procedure adopted by most overseas MRO's is to remove the low bottle/s and service them in a clean environment, which has its merits... but one of the negatives is you you don't have the uniform pressures, and one or more bottles could be over pressure.
Qantas have a standard procedure which requires those persons servicing oxy bottles to complete appropriate training.. we hope that other agents that work on our aircraft are also trained.
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then what was the reason for its failure.
Broadreach
Fortunately there appear to have been no cabin crew working in that galley at the time and who might differ on the subject of "safety risk". They might even wonder a bit at the spokeswoman's aircraft identification skills.
