Qantas 744 Depressurisation
I am just a pilot...but I have been around for a little while...so please accept my comments with that caveat.
I would postulate that the failure started at either, the top or the bottom of the fractured area. That would mean the failure mode was preciptated by either of two completely different causes.
1. If the failure stared at the bottom of the rupture area, it can be seen that the margin of the damage started along the fastener lines. This might possibly be the result of high cycle fatigue and possibly induced by corrosion, poor manufacturing, poor repair or just good old age (high cycle fatigue).
2. If the failure started at the top of the rupture area, then I would start to get a little excited. To my inexperienced view, I can see a panel of metal that seems to show clear deformation from a blunt object trying to escape from inside. There seems to be clear evidence of skin overload and tearing in an area that is not related to (or weakened by) the lines of fasteners. The honeycomb filled wing root fairing in the associated area also seems to have failed in overload and subsequently the aerodynamic forces have caused the failure of the fasteners resulting in detachment of the major portion of the fairing.
My gut feel is with the second suggested mode of failure.
In summary, I am suggesting an overload failure from some mechanical source as opposed to high cycle fatigue emanating from an undetected corrosion induced crack or prior damage.
But, of course this is pure speculation on my part. The investigators will enlighten us in due course with the actual failure mode. I hope this adds to the discussion.
I would postulate that the failure started at either, the top or the bottom of the fractured area. That would mean the failure mode was preciptated by either of two completely different causes.
1. If the failure stared at the bottom of the rupture area, it can be seen that the margin of the damage started along the fastener lines. This might possibly be the result of high cycle fatigue and possibly induced by corrosion, poor manufacturing, poor repair or just good old age (high cycle fatigue).
2. If the failure started at the top of the rupture area, then I would start to get a little excited. To my inexperienced view, I can see a panel of metal that seems to show clear deformation from a blunt object trying to escape from inside. There seems to be clear evidence of skin overload and tearing in an area that is not related to (or weakened by) the lines of fasteners. The honeycomb filled wing root fairing in the associated area also seems to have failed in overload and subsequently the aerodynamic forces have caused the failure of the fasteners resulting in detachment of the major portion of the fairing.
My gut feel is with the second suggested mode of failure.
In summary, I am suggesting an overload failure from some mechanical source as opposed to high cycle fatigue emanating from an undetected corrosion induced crack or prior damage.
But, of course this is pure speculation on my part. The investigators will enlighten us in due course with the actual failure mode. I hope this adds to the discussion.
Join Date: Jun 2006
Location: godsowncountry
Posts: 4
Likes: 0
Received 0 Likes
on
0 Posts
Referance to Boeing Illustrated Parts Catalog (IPC) 35-20-00-02-001 clearly shows on Manufacturers Serial Number (MSN) 24806 which is VH-OJK that there should be an oxygen bottle showing through the gap between Station 800 and 820 which is where the hole is. Where is it? Did IT cause the rupture? My money is on the fact that it played a major part in this incident.
By the way Hi Tech post 284 implies that if it was Oxy then there would be burn marks. Oxy only explodes or burns if there is an ignition source. It supports combustion but does NOT burn in itself.
Also note that the brown stains that people on this forum are implying is corrosion is in fact a brown anti corrosion compound (possibly LPS 3 or boeshield) that is sprayed on the rivet lines during maintenance. Corrosion in this area of B747s is very rare.
Over and out till the 'sperts finish their investigation.
By the way Hi Tech post 284 implies that if it was Oxy then there would be burn marks. Oxy only explodes or burns if there is an ignition source. It supports combustion but does NOT burn in itself.
Also note that the brown stains that people on this forum are implying is corrosion is in fact a brown anti corrosion compound (possibly LPS 3 or boeshield) that is sprayed on the rivet lines during maintenance. Corrosion in this area of B747s is very rare.
Over and out till the 'sperts finish their investigation.
Join Date: Nov 2006
Location: Asia
Posts: 183
Likes: 0
Received 0 Likes
on
0 Posts
An aircraft unit won't decompress as it's not pressurised, the front curtain on it is designed to keep the bags/freight in and dry, nothing else. As for a container "blowing apart". I don't think so.
As for freight coming through the aft wall of Compartment 2. I think this aircraft may have had more problems than just the hole in the fuselage if that had happened
As for freight coming through the aft wall of Compartment 2. I think this aircraft may have had more problems than just the hole in the fuselage if that had happened
Right cargo clown,
I agree with you. By "blow apart", I meant "fall apart." I didn't mean to imply that a ULD is a pressure vessel. It is not. It is a flimsy non-air-tight box with no sides but tin foil doors if it even has that. But it is sitting with higher pressure relative to 30,000 feet as is everything inside the pressure vessel. The differential will instantly suck those flimsy doors off along with whatever was inside. More of an external tornado of air moving from the upper decks towards that hull breech and disrupting anything that gets in the way.
But I'm still surprised to see the bottom of the pallet ripped off the flooring pallet locks, and moved aft if that's what that is.
Join Date: Apr 2008
Location: London
Posts: 26
Likes: 0
Received 0 Likes
on
0 Posts
The location of the damage is right where two of the Oxygen cylinders are approximately STA 800-840 ref IPC 35-20-00 and was wondering whether the passengers actually had a supply of oxygen as all the bottles are linked in parallel so when the bottle left the aircraft the system would quickly bleed away. Obviously in the intial part of the incident there was sufficient Oxygen in the system to open all the PSU doors in the cabin, this may explain why some of the passengers were feeling sick as nausea is a symptom of altitude sickness.
There have been some really good posts in the last 24 hours making this thread worthwhile reading. Unfortunately they are still embedded along the 10-90 rule of only 10% good. 
Some of the best have been from examination of the photos with some experience in either loading and/or maintenance. So to continue I have enhanced some more photos hopefully to match up with some early release factuals from the Australian investigators.
Some of the best have been from examination of the photos with some experience in either loading and/or maintenance. So to continue I have enhanced some more photos hopefully to match up with some early release factuals from the Australian investigators.
Join Date: Nov 2006
Location: Asia
Posts: 183
Likes: 0
Received 0 Likes
on
0 Posts
Right, but we used to cruise at .84 econ on the -200's,
So if he threw out the boards and if he threw out the gear (I know, I know: the gear speed is what on the -400 mach at alt? but it can be done) it's gotta be a higher decent rate than that....
Surely....
So if he threw out the boards and if he threw out the gear (I know, I know: the gear speed is what on the -400 mach at alt? but it can be done) it's gotta be a higher decent rate than that....
Surely....
Join Date: Sep 2007
Location: Paris, France
Posts: 350
Likes: 0
Received 0 Likes
on
0 Posts
Some of the discussion here (and even more so in the media) seems to me like a tremendous dramatization of an incident that harmed no one and simply required an emergency landing. Something made a hole in the aircraft, pressurization was lost, the crew did exactly what it was trained to do, the aircraft behaved exactly as it should, landing was uneventful and nobody was hurt at all. It's almost a non-event. But I guess the hole looks good on TV.
People should be reassured by this, in a way, because even though a hole blew open in the aircraft, it still flew just fine, and everyone got down safely with nothing more than an exciting story to tell the grandkids. All the procedures worked. Nobody was ever in any real danger. That's quite unlike what the fictional Hollywood or mass-media verisons of the story might be. Everything worked by the book and everything went fine. Charleton Heston didn't have to be resurrected to fly the plane, and Joe Patroni could still sleep late.
Some media love having a nice big hole to photograph, although it's difficult to sensationalize it very much without any bodies. Fill the screen with the picture, talk about the "dangerous plunge" as if it were an accident rather than a deliberate and controlled descent, try to find a few passengers emotional enough to put on camera, and lower your voice when you mention that nobody was actually hurt (but be sure to mention the ones who vomit).
The only real concerns here are technical and cannot really be adequately addressed until an investigation is completed. Was this incident linked to the age of the airframe? Was it improper maintenance or operation? Was it simply a freak accident? Ultimately what the industry needs to know is the likelihood that it will happen again: if that likelihood is low, no problem, if it is significant, something will have to be done to reduce it to insignificance. Either way, I don't see anything to worry much about.
Personally I rather like the 747-400, so I hope that it turns out to be something Qantas messed up rather than an issue linked to the age or design of the airframe. Sometimes I get the (highly subjective?) impression that people are trying to find excuses to retire 747s just because they've been on the top of the heap for a couple of decades.
People should be reassured by this, in a way, because even though a hole blew open in the aircraft, it still flew just fine, and everyone got down safely with nothing more than an exciting story to tell the grandkids. All the procedures worked. Nobody was ever in any real danger. That's quite unlike what the fictional Hollywood or mass-media verisons of the story might be. Everything worked by the book and everything went fine. Charleton Heston didn't have to be resurrected to fly the plane, and Joe Patroni could still sleep late.
Some media love having a nice big hole to photograph, although it's difficult to sensationalize it very much without any bodies. Fill the screen with the picture, talk about the "dangerous plunge" as if it were an accident rather than a deliberate and controlled descent, try to find a few passengers emotional enough to put on camera, and lower your voice when you mention that nobody was actually hurt (but be sure to mention the ones who vomit).
The only real concerns here are technical and cannot really be adequately addressed until an investigation is completed. Was this incident linked to the age of the airframe? Was it improper maintenance or operation? Was it simply a freak accident? Ultimately what the industry needs to know is the likelihood that it will happen again: if that likelihood is low, no problem, if it is significant, something will have to be done to reduce it to insignificance. Either way, I don't see anything to worry much about.
Personally I rather like the 747-400, so I hope that it turns out to be something Qantas messed up rather than an issue linked to the age or design of the airframe. Sometimes I get the (highly subjective?) impression that people are trying to find excuses to retire 747s just because they've been on the top of the heap for a couple of decades.
Join Date: Jan 2003
Location: Manchester
Age: 45
Posts: 615
Likes: 0
Received 0 Likes
on
0 Posts
I agree with you. By "blow apart", I meant "fall apart." I didn't mean to imply that a ULD is a pressure vessel. It is not. It is a flimsy non-air-tight box with no sides but tin foil doors if it even has that. But it is sitting with higher pressure relative to 30,000 feet as is everything inside the pressure vessel. The differential will instantly suck those flimsy doors off along with whatever was inside. More of an external tornado of air moving from the upper decks towards that hull breech and disrupting anything that gets in the way.
But I'm still surprised to see the bottom of the pallet ripped off the flooring pallet locks, and moved aft if that's what that is.
But I'm still surprised to see the bottom of the pallet ripped off the flooring pallet locks, and moved aft if that's what that is.
)Far more than "tinfoil". To make one fall apart would need considerably more force than a rapid decompression. As they aren't a pressure vessel, I'm sure an 8psi differential would just blow the curtain open, or more likely push the curtain out to release the pressure far slower than a hull breach would.
As for the pallet jumping the locks. Again, I can't see it, the locks and pallet base are stressed to silly levels for turbulence purposes, something like 6g with a full PMC. I really can't see a decompression getting anywhere near those levels. Now if the pallet weren't locked down properly.......
Join Date: Jul 1999
Location: 58-33N. 00-18W. Peterborough UK
Posts: 3,040
Likes: 0
Received 0 Likes
on
0 Posts
it's gotta be a higher decent rate than that....
Join Date: Mar 2007
Location: Roguesville, cloud cuckooland
Posts: 1,197
Likes: 0
Received 16 Likes
on
5 Posts
Blacksheep and others. No dramatisation here. I'll say it one last time; this was not a canned simulator depressurisation exercise. (Bang, don mask, initiate descent, checklist, land.)This crew had multiple unrelated system failures to deal with subsequent to the depressurisation. The sort of failures that one may criticise in a simulator exercise as being negative training due to being "too unrealistic". They did a helluva job. Nuff said.
Join Date: Nov 2000
Location: not a million miles from old BKK
Posts: 494
Likes: 0
Received 0 Likes
on
0 Posts
Forget
Yup.
There's been a 'bang', the cabin has de-pressurised, as Captain you have no idea what caused it or what structural damage the aircraft may have suffered, you know you have x number of minutes of passenger oxygen available to get you down to 12,000 feet or so where the air is breathable.
Rather than stress the airframe with a maximum rate of descent one might slow it down a bit to be on the safe side.
There's been a 'bang', the cabin has de-pressurised, as Captain you have no idea what caused it or what structural damage the aircraft may have suffered, you know you have x number of minutes of passenger oxygen available to get you down to 12,000 feet or so where the air is breathable.
Rather than stress the airframe with a maximum rate of descent one might slow it down a bit to be on the safe side.
Looking at Lomapaseo's enhanced photos, I am led to suspect that:
- the initial rupture was lower down and abrupt -- that piece seems to be missing
- sucked baggage plugged the initial hole
- the upper breach is weakened structure that peeled away in a less abrupt fashion to let the air out.
Warning Toxic!
Disgusted of Tunbridge
Disgusted of Tunbridge
Join Date: Jan 2005
Location: Hampshire, UK
Posts: 4,011
Likes: 0
Received 0 Likes
on
0 Posts
It is getting a bit tiring amateur sleuths venting their opinions on what happened and in what sequence! I am happy to read from someone who knows what they are talking about and is in the industry, but please no more armchair opinions! It is becoming a cacophany of opinions from instant amateur self-appointed accident investigators, and there is just no way of picking out the good information from the absolute dross and tosh! We now have people telling us how airline pilots think having never flown a big jet?
Might I suggest anyone with an opinion on what happened preface their posting with what their expertise is please? It is becoming unreadable! 17 pages of which 15 are dross. The 'I must be first with a possible explanation' brigade have struck even here. Shooting stars......love it! But dross, nevertheless.
Might I suggest anyone with an opinion on what happened preface their posting with what their expertise is please? It is becoming unreadable! 17 pages of which 15 are dross. The 'I must be first with a possible explanation' brigade have struck even here. Shooting stars......love it! But dross, nevertheless.
Join Date: Jun 2005
Location: AEP
Age: 80
Posts: 1,420
Likes: 0
Received 0 Likes
on
0 Posts
From a 747 pilot
Hello to everyone -
xxx
Captain 747 "Classic" here - also TRI/TRE with 6100 command hours on type...
Not qualified on 400, but I fly the 200s, and have flown 300s, rather similar.
Not a pilot with Qantas.
xxx
In view of the location of the damage, I first suspected explosion of O2 bottles.
Maybe, or maybe not. Who knows at this stage. Investigations take time.
All baggage were likely inside a container. Yet they appear on the picture...
Or were they loaded as bulk...?
I would say maybe corrosion - toilets probably above that area...
I do not know the QF 400 cabin/toilets location and configuration.
xxx
My airline leased former VH-EBA, an old 238, ex QF. Was a high time airplane.
Low cycle it was as well, and in rather good condition.
QF is above average reputation in maintenance. QF crews are professionals.
xxx
Apparently, the incident happened in cruise at FL 290, initial cruise level.
Maybe the cabin was already at its preprogrammed cabin altitude -
So, the cabin pressure differential would have been still low - 6 Psi... ?
xxx
I do not think that the emergency descent was as spectacular as described.
Such a maneuver is generally flown at about 6,000 feet per minute.
Lesser rate even, 5,000 ft/min if flown using autopilot.
Expediate down to FL 140, then shallow descent to FL 100...
Unlikely also that they got the gear down for a steeper descent.
A "clean configuration" is preferable when structural integrity is questionable.
I am certain the flight crew suspected structural problem. I would have.
We practice emergency descents in simulators every 6 months.
Nothing spectacular as a maneuver. If time left, give a PA to cabin...
Obviously, the "rubber jungle" hanging in the cabin is impressive to SLFs.
xxx
I had a different but somehow "similar" incident long ago, flying a 707-321.
The plexiglas lens cover (landing lights) had blown near the RH wing root.
The airplane flew with slight buffets due to disturbed airflow over elevators.
Possible this crew here, got same buffets during the flight into Manila.
xxx
For the rest - I leave the Pprune experts and press reporters decide.
Retiring in 110 days - Probably one of my last posts.
Happy contrails -
xxx
Captain 747 "Classic" here - also TRI/TRE with 6100 command hours on type...
Not qualified on 400, but I fly the 200s, and have flown 300s, rather similar.
Not a pilot with Qantas.
xxx
In view of the location of the damage, I first suspected explosion of O2 bottles.
Maybe, or maybe not. Who knows at this stage. Investigations take time.
All baggage were likely inside a container. Yet they appear on the picture...
Or were they loaded as bulk...?
I would say maybe corrosion - toilets probably above that area...
I do not know the QF 400 cabin/toilets location and configuration.
xxx
My airline leased former VH-EBA, an old 238, ex QF. Was a high time airplane.
Low cycle it was as well, and in rather good condition.
QF is above average reputation in maintenance. QF crews are professionals.
xxx
Apparently, the incident happened in cruise at FL 290, initial cruise level.
Maybe the cabin was already at its preprogrammed cabin altitude -
So, the cabin pressure differential would have been still low - 6 Psi... ?
xxx
I do not think that the emergency descent was as spectacular as described.
Such a maneuver is generally flown at about 6,000 feet per minute.
Lesser rate even, 5,000 ft/min if flown using autopilot.
Expediate down to FL 140, then shallow descent to FL 100...
Unlikely also that they got the gear down for a steeper descent.
A "clean configuration" is preferable when structural integrity is questionable.
I am certain the flight crew suspected structural problem. I would have.
We practice emergency descents in simulators every 6 months.
Nothing spectacular as a maneuver. If time left, give a PA to cabin...
Obviously, the "rubber jungle" hanging in the cabin is impressive to SLFs.
xxx
I had a different but somehow "similar" incident long ago, flying a 707-321.
The plexiglas lens cover (landing lights) had blown near the RH wing root.
The airplane flew with slight buffets due to disturbed airflow over elevators.
Possible this crew here, got same buffets during the flight into Manila.
xxx
For the rest - I leave the Pprune experts and press reporters decide.
Retiring in 110 days - Probably one of my last posts.
Happy contrails -