Qantas 744 Depressurisation
Quote:
- what's your gripe about that ?
Blacksheep # 306..... read #297 and # 329, maybe you didn't mean it that way, but I'm not alone in interpreting your remarks as a snide sideswipe at the crew - uncalled for.
I agree that the whole thing has been over-dramatised, but what's new in that, regrettable or not ? Many years ago "Roger Bacon", the satirical columnist of "Flight" , threatened to load an aircraft with explosive and ignite it over the Farnborough Air Show so that 100,000 "experts" could categorically state that the aircraft was on fire in the air ! Nothing's changed since then. ( Nb "X" is an unknown quantity, and a spurt is a drip under pressure )
Time we all shut up until some facts emerge.
- what's your gripe about that ?
Blacksheep # 306..... read #297 and # 329, maybe you didn't mean it that way, but I'm not alone in interpreting your remarks as a snide sideswipe at the crew - uncalled for.
I agree that the whole thing has been over-dramatised, but what's new in that, regrettable or not ? Many years ago "Roger Bacon", the satirical columnist of "Flight" , threatened to load an aircraft with explosive and ignite it over the Farnborough Air Show so that 100,000 "experts" could categorically state that the aircraft was on fire in the air ! Nothing's changed since then. ( Nb "X" is an unknown quantity, and a spurt is a drip under pressure )
Time we all shut up until some facts emerge.
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Idle speculation:
Litebulbs comment about the O2 cylinder visible in post 358 pix #2 looks right to the eyeball. From the same pix, the white harness dimly seen just forward of the green object looks as though it might be a collection of four to six white tubes for carrying O2 toward the cabin.
If another O2 cylinder were located just forward of the green shape in the pic, then its lower end might line up rather neatly with the bottom of the visible hole, and its upper end with the tongue of pressure hull skin bent outward at top of the damage area. A pressure cylinder failure originating near the base of the inside surface would provide rocket power to propel much of the disintegrating cylinder outward and upward in a manner consistent with the observed hole.
How would a high-test cylinder suddenly decide to disassemble in this manner? Perhaps the very same cargo pallet visible in the post-incident pictures included a rock or ice-climbing pick - with a very sharp, hard steel point (or something similar..hard, pointy) and some still unexplained shift of the cargo bulk brought this chisel point in contact with the pressurized O2 cylinder, allowing vibration to hammer away at the surface and eventually causing a stress failure at the lower inside-facing part of the gas container - with results as now may be seen.
Litebulbs comment about the O2 cylinder visible in post 358 pix #2 looks right to the eyeball. From the same pix, the white harness dimly seen just forward of the green object looks as though it might be a collection of four to six white tubes for carrying O2 toward the cabin.
If another O2 cylinder were located just forward of the green shape in the pic, then its lower end might line up rather neatly with the bottom of the visible hole, and its upper end with the tongue of pressure hull skin bent outward at top of the damage area. A pressure cylinder failure originating near the base of the inside surface would provide rocket power to propel much of the disintegrating cylinder outward and upward in a manner consistent with the observed hole.
How would a high-test cylinder suddenly decide to disassemble in this manner? Perhaps the very same cargo pallet visible in the post-incident pictures included a rock or ice-climbing pick - with a very sharp, hard steel point (or something similar..hard, pointy) and some still unexplained shift of the cargo bulk brought this chisel point in contact with the pressurized O2 cylinder, allowing vibration to hammer away at the surface and eventually causing a stress failure at the lower inside-facing part of the gas container - with results as now may be seen.
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IT WAS NOT AN OXYGEN BOTTLE EXPLOSION.
2 ways an oxygen bottle explodes:-
1. The head fitting (regulator) blows off. In this incident the bottle would take-off like a rocket, and because its orientation onboard the aircraft was in a vertical position then it would have left a big hole in the bottom of the fuselage. And yes they are adequately secured and have over-pressure relief valves and check valves and thermal relief and every other protection device you could think off . So this did not happen.
2. A breach in the wall of the cylinder, very unlikely but lets say for the argument this did happen. This would be equivalent in force to an explosion as large a bomb going off, and depending on the direction of the blast possible shrapnel damage. If blast direction was inside then expect to see the cabin floor being lifted. If the blast direction was outboard then expect to see more damage and not radiating from a small point in the middle of the hole in fuselage.
Oxygen bottles just don't explode like this, if it was contamination from galley waste that triggered the explosion combining with small leak from cylinder then again the regulator is where that would have occurred.
Yes there is at least one bottle missing but only because the structure supporting it has disappeared.
THINK AGAIN.
2 ways an oxygen bottle explodes:-
1. The head fitting (regulator) blows off. In this incident the bottle would take-off like a rocket, and because its orientation onboard the aircraft was in a vertical position then it would have left a big hole in the bottom of the fuselage. And yes they are adequately secured and have over-pressure relief valves and check valves and thermal relief and every other protection device you could think off . So this did not happen.
2. A breach in the wall of the cylinder, very unlikely but lets say for the argument this did happen. This would be equivalent in force to an explosion as large a bomb going off, and depending on the direction of the blast possible shrapnel damage. If blast direction was inside then expect to see the cabin floor being lifted. If the blast direction was outboard then expect to see more damage and not radiating from a small point in the middle of the hole in fuselage.
Oxygen bottles just don't explode like this, if it was contamination from galley waste that triggered the explosion combining with small leak from cylinder then again the regulator is where that would have occurred.
Yes there is at least one bottle missing but only because the structure supporting it has disappeared.
THINK AGAIN.
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Firstly, I have no aviation knowledge.
Maybe I've misread the thread, but I haven't seen reference to what looks like (original photo) a section of the fuselage wall below the black bags, inside the plane, and reversed.
At the bottom, and in the middle of this section, could there be the top of an oxygen bottle + regulator?
Maybe I've misread the thread, but I haven't seen reference to what looks like (original photo) a section of the fuselage wall below the black bags, inside the plane, and reversed.
At the bottom, and in the middle of this section, could there be the top of an oxygen bottle + regulator?
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Oxygen Bottle?
According to an article on theage.com.au site
‘a source close to the Civil Aviation Safety Authority said exploding oxygen cylinders were the likely cause of the rupture, and would be the main focus of the investigation, as they were stored in the exact location of the explosion and there were no signs of fire.’
Bottles do not explode spontaneously. They vent if over pressure.
‘a source close to the Civil Aviation Safety Authority said exploding oxygen cylinders were the likely cause of the rupture, and would be the main focus of the investigation, as they were stored in the exact location of the explosion and there were no signs of fire.’
Bottles do not explode spontaneously. They vent if over pressure.
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the fire bottles for the cargo area around frame 830, (i believe). They are located on the Right hand side within the area of the hull breach, A good source has confirmed that these fire bottle expiry dates are being looked at as well as the last time they were inspected.
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Looking at the high resolution photos, the red bags appear to me to
be containing rope. This would seem to be again to me that they
are bags containing nets for new pallets/ULDS. When you ship a stack
of pallets, you must have nets for them as well. I know after the
Arrow DC8 accident in MIA, the regulations were upgraded to state that
all nets had to be secured to the pallets in some way. But, when ULDS
are new, the nets have not been attached yet, they are loaded in
sacks and stowed on the pallets for shipment. Or does any one remember
having to get a new net for replacement? You had to open a sack, sometimes red, to get the new net. Could it be these were loaded on a
stack of empty pallets, said pallets shifted and the shifted pallets
hit an o2 bottle behind the interior fairing? By hitting the bottle, I mean
knocked the stem off.
be containing rope. This would seem to be again to me that they
are bags containing nets for new pallets/ULDS. When you ship a stack
of pallets, you must have nets for them as well. I know after the
Arrow DC8 accident in MIA, the regulations were upgraded to state that
all nets had to be secured to the pallets in some way. But, when ULDS
are new, the nets have not been attached yet, they are loaded in
sacks and stowed on the pallets for shipment. Or does any one remember
having to get a new net for replacement? You had to open a sack, sometimes red, to get the new net. Could it be these were loaded on a
stack of empty pallets, said pallets shifted and the shifted pallets
hit an o2 bottle behind the interior fairing? By hitting the bottle, I mean
knocked the stem off.
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Rainboe: re. TWA crash
I have a vivid memory of a widely-reproduced photograph of the TWA aircraft on the ground. It landed on its starboard side — curious in itself. Accident investigators would have had a bit of a job to get at the area fwd of the (absent) stbd wing. Conclusive proof of foul play would have been chemical residues from explosives in the hold and around any breach in it; but perhaps they just found evidence of a substantial fire? Were unfiltered enquiry findings ever released?
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If I were designing a piping system fed by multiple high-pressure gas bottles, I would expect to connect each bottle through a non-return valve. That way it would be possible to remove a bottle whilst leaving others in place and without depressurising the whole system.
Can anyone advise us whether oxygen gas systems on aircraft in general and on the 744 in particular have such fittings? If they do, that could explain why one bottle could escape without the emergency oxygen system failing completely.
Can anyone advise us whether oxygen gas systems on aircraft in general and on the 744 in particular have such fittings? If they do, that could explain why one bottle could escape without the emergency oxygen system failing completely.
There was a report in the age that passengers complained on no air...
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I believe that Boeing is aware of the potential damage from leaking oxygen bottles and other pressurized sources in the 747 cargo hold.
The 747-8 has a new and interesting pressure relief valve to prevent this sort of damage.
Presumably, Boeing will offer this valve for retrofit.
The 747-8 has a new and interesting pressure relief valve to prevent this sort of damage.
Presumably, Boeing will offer this valve for retrofit.
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Looking at the pictures and the way the metal has folded, it would appear that the initial fracture of the hull may have come from around the manufacture join.
The metal around this area looks like it has been folded into the airflow before the wing to body panel disappeared the other damage like it has happened after the fact and it has peeled back with the air flow.
something to think about
The metal around this area looks like it has been folded into the airflow before the wing to body panel disappeared the other damage like it has happened after the fact and it has peeled back with the air flow.
something to think about
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Airbubba "51 planes"
"QF has had some conspicuous bad luck with O2 bottles recently, they were filled with Nitrogen on 51 planes a year or so ago. Perhaps just a coincidence, we'll see..."
Hi there Airbubba,
It was actually only 1 aircraft that had the Nitrogen in the oxy system. Just thought I would clear that up for all.
PS I am a QF LAME.
Devcon
Hi there Airbubba,
It was actually only 1 aircraft that had the Nitrogen in the oxy system. Just thought I would clear that up for all.
PS I am a QF LAME.
Devcon
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The 744 passenger oxygen bottles feed into a common manifold. Each bottle has a pressure relief valve (or rather, frangible disc) which allows the bottles' contents to discharge overboard if the internal pressure is too high. The pressure required to activate this relief valve is significantly higher than the typical system pressure (1800psi), but presumably far lower than the pressure required to rupture a serviceable bottle 
To change a pax bottle on a Qantas 744, you have to close all the other bottles, both in the right hand (Fwd) cargo sidewall and in the (Fwd) cargo ceiling.
Unless I have overlooked something obvious, if one of the bottles ruptured, I would say that the contents of the entire system would start venting. Question to experts: Do the pressure reducers shown in the Boeing Schematics (35-11-00) have inbuilt check valves?
On this type of pax oxygen system, the bottles feed 3 flow-control units. These allow the oxygen to get to the passengers (after being activated by various manual and automatic methods). The oxygen masks drop from the overhead panels via doors which are unlatched by the oxygen pressure surge coming down the lines. Clearly in the videos, the masks have dropped. Ergo... at least some pressure was present. See other PPRuNe message threads for interesting information on the effectiveness of pax oxygen systems. Once the door has released and the mask has dropped, the passenger has to physically pull down on the mask (to allow oxygen to flow from the overhead unit)
I wonder how many of the passengers remembered to pull down on the oxygen masks after paying careful attention to the preflight safety demonstration? There is, of course, automatic announcements during a decompression to remind them
Rgds.
NSEU
To change a pax bottle on a Qantas 744, you have to close all the other bottles, both in the right hand (Fwd) cargo sidewall and in the (Fwd) cargo ceiling.
Unless I have overlooked something obvious, if one of the bottles ruptured, I would say that the contents of the entire system would start venting. Question to experts: Do the pressure reducers shown in the Boeing Schematics (35-11-00) have inbuilt check valves?
On this type of pax oxygen system, the bottles feed 3 flow-control units. These allow the oxygen to get to the passengers (after being activated by various manual and automatic methods). The oxygen masks drop from the overhead panels via doors which are unlatched by the oxygen pressure surge coming down the lines. Clearly in the videos, the masks have dropped. Ergo... at least some pressure was present. See other PPRuNe message threads for interesting information on the effectiveness of pax oxygen systems. Once the door has released and the mask has dropped, the passenger has to physically pull down on the mask (to allow oxygen to flow from the overhead unit)
I wonder how many of the passengers remembered to pull down on the oxygen masks after paying careful attention to the preflight safety demonstration? There is, of course, automatic announcements during a decompression to remind them
Rgds.
NSEU
Last edited by NSEU; 27th Jul 2008 at 01:24.
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Qantas pilot blames MAS
This from The Star :
MAS denies Qantas senior pilot’s claims
By LESTER KONG
PETALING JAYA: Malaysia Airlines has refuted a Qantas pilot's allegation that maintenance of the Qantas Boeing 747 that suffered a ruptured fuselage on Friday had been outsourced to Malaysia, as being baseless.
The Australian-based airline has also confirmed the claim to be untrue.
MAS senior general manager Mohd Roslan Ismail in a statement yesterday said that MAS only handled the engineering and maintenance of Qantas’ Boeing 737 aircraft and not the 747.
He added that MAS’ engineering and maintenance division held an excellent track record.
“The increasing number of foreign airlines who outsource their aircraft to us is a testimony to our success in this field,” he said, adding that third party contracts comprise 40% of their business.
In a press conference in Sydney, Qantas head of engineering David Cox said all of the plane's servicing was undertaken in Australia.
An unnamed senior Qantas pilot yesterday told The Daily Telegraph, a Sydney tabloid, that a mid-air calamity on Qantas flight QF30 from London to Melbourne could have been caused by the airline’s outsourcing of maintenance to Malaysia.
A rupture on the fuselage of the 17-year-old aircraft occurred while flying at 8,839m over the South China Sea from a Hong Kong stopover and forced the pilot to perform an emergency landing in Manila at 11am.
None of the 346 passengers and 19 crew were hurt in the emergency landing.
A sheet of metal was torn from the front of the right wing. The plane had received a new interior at Victoria’s Avalon airport in March.
Wow, big claims from a skygod............the QF engineers will be real happy if it's true; no more outsourcing to MAS, SQ and China. So the recent strike for more $s gets a helping hand here!
MAS denies Qantas senior pilot’s claims
By LESTER KONG
PETALING JAYA: Malaysia Airlines has refuted a Qantas pilot's allegation that maintenance of the Qantas Boeing 747 that suffered a ruptured fuselage on Friday had been outsourced to Malaysia, as being baseless.
The Australian-based airline has also confirmed the claim to be untrue.
MAS senior general manager Mohd Roslan Ismail in a statement yesterday said that MAS only handled the engineering and maintenance of Qantas’ Boeing 737 aircraft and not the 747.
He added that MAS’ engineering and maintenance division held an excellent track record.
“The increasing number of foreign airlines who outsource their aircraft to us is a testimony to our success in this field,” he said, adding that third party contracts comprise 40% of their business.
In a press conference in Sydney, Qantas head of engineering David Cox said all of the plane's servicing was undertaken in Australia.
An unnamed senior Qantas pilot yesterday told The Daily Telegraph, a Sydney tabloid, that a mid-air calamity on Qantas flight QF30 from London to Melbourne could have been caused by the airline’s outsourcing of maintenance to Malaysia.
A rupture on the fuselage of the 17-year-old aircraft occurred while flying at 8,839m over the South China Sea from a Hong Kong stopover and forced the pilot to perform an emergency landing in Manila at 11am.
None of the 346 passengers and 19 crew were hurt in the emergency landing.
A sheet of metal was torn from the front of the right wing. The plane had received a new interior at Victoria’s Avalon airport in March.
Wow, big claims from a skygod............the QF engineers will be real happy if it's true; no more outsourcing to MAS, SQ and China. So the recent strike for more $s gets a helping hand here!
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In the second picture of #358, on the left hand side of the hole, I believe you can see what looks like an O2 bottle. I have had the privilege to hump these things off and on B74's in the past, so I have been up close and personal with them, so I believe that I am at least qualified to suggest that it could be a bottle.
I await a flame!!
I await a flame!!
No flame, how about an attaboy? Good eyeball, good recall.
It looks like a white cylinder all right in that picture at the bottom. I used to have some like that in my hangar. Did you ever notice: did they have red base primer underneth the top coat of white bottle coating? I see red scratch marks on the side.
Does this look like a composite bottle in the picture to you? The end doesn't look like metal to me at least.
"Vortsa" said:
IT WAS NOT AN OXYGEN BOTTLE EXPLOSION.
2 ways an oxygen bottle explodes:-
1. The head fitting (regulator) blows off. In this incident the bottle would take-off like a rocket, and because its orientation onboard the aircraft was in a vertical position then it would have left a big hole in the bottom of the fuselage. And yes they are adequately secured and have over-pressure relief valves and check valves and thermal relief and every other protection device you could think off . So this did not happen.
2. A breach in the wall of the cylinder, very unlikely but lets say for the argument this did happen. This would be equivalent in force to an explosion as large a bomb going off, and depending on the direction of the blast possible shrapnel damage. If blast direction was inside then expect to see the cabin floor being lifted. If the blast direction was outboard then expect to see more damage and not radiating from a small point in the middle of the hole in fuselage.
Oxygen bottles just don't explode like this, if it was contamination from galley waste that triggered the explosion combining with small leak from cylinder then again the regulator is where that would have occurred.
Yes there is at least one bottle missing but only because the structure supporting it has disappeared.
THINK AGAIN.
2 ways an oxygen bottle explodes:-
1. The head fitting (regulator) blows off. In this incident the bottle would take-off like a rocket, and because its orientation onboard the aircraft was in a vertical position then it would have left a big hole in the bottom of the fuselage. And yes they are adequately secured and have over-pressure relief valves and check valves and thermal relief and every other protection device you could think off . So this did not happen.
2. A breach in the wall of the cylinder, very unlikely but lets say for the argument this did happen. This would be equivalent in force to an explosion as large a bomb going off, and depending on the direction of the blast possible shrapnel damage. If blast direction was inside then expect to see the cabin floor being lifted. If the blast direction was outboard then expect to see more damage and not radiating from a small point in the middle of the hole in fuselage.
Oxygen bottles just don't explode like this, if it was contamination from galley waste that triggered the explosion combining with small leak from cylinder then again the regulator is where that would have occurred.
Yes there is at least one bottle missing but only because the structure supporting it has disappeared.
THINK AGAIN.
) that it can't blow up, tank shrapnel has been reported as rumor by one source. As remote as the odds are, it now appears we lost a bottle(s) in this incident. The question of course now is, was the bottle bursting a secondary result of something else impacting it, or did it cause the hull/floor failure in the first place?This is the first time I've ever heard of a bottle failure in flight...... very odd. Anybody else ever hear of a bottle failure on an inflight jet? (no, Valuejet in the Glades doesn't count.)
Last edited by pacplyer; 27th Jul 2008 at 01:51. Reason: quotes added, corrections
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An unnamed senior Qantas pilot
How intelligent are you?