Qantas 744 Depressurisation
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It helps (a bit). I presume that the cylinders shown are not in the location of the 'missing' cylinder.
We really need a view more to the left to see the depth of the space in which the oxygen cylinders (of this aircraft) are positioned (and hopefully showing the support bracket).
I appreciate that the upper support is unlikely to break away, so the cylinder will be restrained in its original lateral position, but if the lower support fails . . .
We really need a view more to the left to see the depth of the space in which the oxygen cylinders (of this aircraft) are positioned (and hopefully showing the support bracket).
I appreciate that the upper support is unlikely to break away, so the cylinder will be restrained in its original lateral position, but if the lower support fails . . .
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Qantas has investigated the complaints from some pax that the system was not working correctly
Water tanks in the photo. Aft end of forward hold.
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Is it possible that the 'ST' in the pictures, last one post 492, that was first reported as a 'golf club' could be the curtain in the picture post 521 with 'STA 700' printed on it?
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Only familiar with smaller bottles than these but welding caps to a tube introduces extra problems hence bottles are made in one piece (a similar deep drawing process to cartridge cases). Welded pressure vessels tend to be restricted to low pressures (100's of psi) or big stuff where it is unavoidable.
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@Nov71
Upload it here for example from your pc
ImageShack® - Image Hosting
than copy and paste to the pprune image link.
cheers
Upload it here for example from your pc
ImageShack® - Image Hosting
than copy and paste to the pprune image link.
cheers
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Nov71:
Wrong way round, surely. You take the gas at high pressure and let it expand rapidly and it gets cold, standard refrigeration technique. You'd only get heat if there was ignition, and no one has mentioned any sign of that so far.
Oh, and keep up the good work, those providing photos, diagrams and explanations of systems, it's very educational.
O2 escaping at high pressure even from a slow leak, can create high temps (adiabatic )
Oh, and keep up the good work, those providing photos, diagrams and explanations of systems, it's very educational.
Nov71;
The advice to upload your image(s) to a hosting site is good - Image Shack is fine and there are others.
Once the images are uploaded to the hosting site you've chosen, they are assigned a "URL" or a link. The link to your photo on the hosting site is pasted in forums such as this one.
Copy the link, (highlight it on the hosting site, then click CTRL C). Navigate to the PPRuNe page/thread you want, click on "reply" to open the thread (I know all this is blindingly obvious but for clarity I'm not skipping a step). The click on the small yellow image of mountains, which will say "Insert Image" - when the small dialogue box pops up it will have the "http://" portion of the link ready - you can either delete that portion and click on CTRL V to paste the entire link to your hosted image in the space or you can omit the "http" blahblah part - at this point you can experiment!
You might shrink your images before you post them so they aren't twice screen size, for example - try 640 x 480 for message boards.
The key is to use the correct link as different forums require different links. PPRuNe seems to require the "Direct" link, (the one beginning with "http://" etc). That worked for me when I was trying to upload a while back. Good luck.
The advice to upload your image(s) to a hosting site is good - Image Shack is fine and there are others.
Once the images are uploaded to the hosting site you've chosen, they are assigned a "URL" or a link. The link to your photo on the hosting site is pasted in forums such as this one.
Copy the link, (highlight it on the hosting site, then click CTRL C). Navigate to the PPRuNe page/thread you want, click on "reply" to open the thread (I know all this is blindingly obvious but for clarity I'm not skipping a step). The click on the small yellow image of mountains, which will say "Insert Image" - when the small dialogue box pops up it will have the "http://" portion of the link ready - you can either delete that portion and click on CTRL V to paste the entire link to your hosted image in the space or you can omit the "http" blahblah part - at this point you can experiment!
You might shrink your images before you post them so they aren't twice screen size, for example - try 640 x 480 for message boards.
The key is to use the correct link as different forums require different links. PPRuNe seems to require the "Direct" link, (the one beginning with "http://" etc). That worked for me when I was trying to upload a while back. Good luck.
I'd just toss in this caution in looking at the various post-event pictures of the fuselage hole.
All those flaps of aluminum spent a long time after the event flapping in a 250-knot breeze until the plane landed. The post-landing shapes and extent of twisting or dislodgment may be quite a bit different in the pictures than they were at the actual moment of the "event" or immediately thereafter.
Tears may have grown larger - pieces that were originally bowed "out" or "in" may have bent back the other way over time in the airstream, depending on a host of factors that we can't even guess at given the disrupted airflow in the area (remaining shards of the fairing, the torn metal itself).
I do agree that the piece of beige cloth showing "ST(A?) below the "parcels" is likely one of the hold wall curtains - not necessarily "STA 700" because other curtains are similarly labeled with station numbers, but it is a probable suspect.
There is also CLEARLY no sign whatever of combustion or heat effects on the plasticky red and black wrapping materials plugging the hole, which would be present if this were a chemical blast. Those dacron/nylon/polyethylene-type materials are very sensitive to heat and fire and would quickly show discoloration and charring if there had been any kind of flame/blast, whether or not accelerated with O2.
Which does not rule out an O2 tank (or piping segment) as a physical cause - either as a source of gas pressure, perhaps violent, or as a source of metal wearing on the aircraft structure.
An aside - as a journalist I share everyone else's dismay (disgust?) with the sensational and sloppy reporting accompanying this incident (and other aviation incidents). Even on a smaller scale I am constantly having to explain to colleagues that, e.g. an airplane "stalling" does not mean the engine quit - etc. etc. I'm considering writing a "Reporter's Guide to Aviation" for the staffers at my newspaper - but it will always be an uphill battle, I'm afraid.
All those flaps of aluminum spent a long time after the event flapping in a 250-knot breeze until the plane landed. The post-landing shapes and extent of twisting or dislodgment may be quite a bit different in the pictures than they were at the actual moment of the "event" or immediately thereafter.
Tears may have grown larger - pieces that were originally bowed "out" or "in" may have bent back the other way over time in the airstream, depending on a host of factors that we can't even guess at given the disrupted airflow in the area (remaining shards of the fairing, the torn metal itself).
I do agree that the piece of beige cloth showing "ST(A?) below the "parcels" is likely one of the hold wall curtains - not necessarily "STA 700" because other curtains are similarly labeled with station numbers, but it is a probable suspect.
There is also CLEARLY no sign whatever of combustion or heat effects on the plasticky red and black wrapping materials plugging the hole, which would be present if this were a chemical blast. Those dacron/nylon/polyethylene-type materials are very sensitive to heat and fire and would quickly show discoloration and charring if there had been any kind of flame/blast, whether or not accelerated with O2.
Which does not rule out an O2 tank (or piping segment) as a physical cause - either as a source of gas pressure, perhaps violent, or as a source of metal wearing on the aircraft structure.
An aside - as a journalist I share everyone else's dismay (disgust?) with the sensational and sloppy reporting accompanying this incident (and other aviation incidents). Even on a smaller scale I am constantly having to explain to colleagues that, e.g. an airplane "stalling" does not mean the engine quit - etc. etc. I'm considering writing a "Reporter's Guide to Aviation" for the staffers at my newspaper - but it will always be an uphill battle, I'm afraid.
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I contribute not as an aviation engineer, but as a test engineer who was responsible for investigating failures of experimental vehicles - a sort of accident investigation engineer. The failures were not previously documented (as the vehicles were the first examples of their type) so it was important to quarantine the vehicle, interview the operator(s) then sift through the information and evidence, remaining open-minded (including 'meteor strikes' and the like) until a sufficient amount of information had been collected to create a plausible scenario. Of course I then had to reproduce the failure in order to prove that the analysis was accurate, rather than merely 'adding a patch' (which probably came later, then I had to prove that the fix solved the problem before it could be released for production). Of course we had rigs on which to test (as well as accelerated vehicle operating schedules) in order to speed up the overall development duration.
Think Comet fatigue test tank:-
Think Comet fatigue test tank:-
The Ministry of Civil Aviation decided upon a unique test to find out. They built a tank large enough to hold one of the grounded Comets. The wings protruded from water-tight slots in the sides of the tank. Then the tank and cabin were flooded with water. The water pressure inside the cabin would be raised to eight and a quarter pounds per square inch to simulate the pressure encountered by a Comet at 35,000 feet. It would be held there for three minutes and then lowered while the wings were moved up and down by hydraulic jacks. The hydraulic jacks would simulate the flexing that naturally occurs in aircraft wings during flight. This process continued non-stop, 24 hours a day. This torture test continued until the cabin in the tank had been subjected to the stresses equivalent to 9,000 hours of actual flying. Suddenly, the pressure dropped. The water was drained and the fuselage examined. The investigators were horrified to find a split in the fuselage. It began with a small fracture in the corner of an escape hatch window and extended for eight feet. Metal fatigue! Had the Comet not been under water, the cabin would have exploded like a bomb. Several months later the results of this test were corroborated when an Italian trawler recovered a large section of cabin roof from the sea. A crack had started in the corner of a navigation window on top of the fuselage. Like the escape hatch window of the test Comet, it had square corners. The square design of the windows was the major flaw that doomed the Comet.
Years back I worked in a seasonal mine. in the Spring when we came back in several O2 welding bottles had frozen valves, as we could not leave these in the landfill due to hazard to the Cat buldozing stuff we sat back 100m and shot the valves off, the bottles took of like a shot. 2500psi more or less has a bunch of thrust
The Reverend
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Lomapaseo, your picture of the FWD Cargo hold and the four cylindrical objects reveal the potable water tanks and not the oxygen cylinders. Good picture though, must have been taken on the production line in Seattle.
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O2 Bottle
Okay, folks, we agree that if an 02 bottle ruptured and the concentration of oxygen encountered grease or some other combustible there would be evidence of an incendiary blast, because there would have been just such...
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?
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?
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Planes49 mumbled:
Well Planes49, we just had to endure your little grammatically incorrect jewel there. There are at least 100 INFORMED posts on maintenance which this event is turning towards, which as just a driver (which I doubt even that) you wouldn't necessarily be qualified to pass judgement on. Do you have an A&P? Doesn't sound like it.
I think we need to realize where we are. We are in rumors and news. Not Planes49's private ground school. Oxygen tanks don't just ride around on -400 models. And of course there's going to be an accident report. I suggest you log off and wait for it if it's such a struggle to "fight" through posts you don't understand.
I'm reminded of the basics of free speech. I think we need to learn how to selectively read instead of trying to coerce others into putting up what we want to see posted.
Personally, I encounter a nugget like "joint" or "should keep there [sic] comments to themselves" and I just skip to the next post.
Thanks to the usual posters for putting up those fantastic photos and schematics. Makes this a highly entertaining and intriguing thread.
As an ex -400 driver I have fought my way through a lot of the 504 posts.
Of these, about 30 contain INFORMED comments about the 400. The rest should keep there comments to something they know about, like their own type, if they have one! ( ie- there doesn't appear to be a cargo door there!).
I wouldn't be at all surprised that there will be an accident report that will tell us the facts.
Happy flying.( to those that do!)
Of these, about 30 contain INFORMED comments about the 400. The rest should keep there comments to something they know about, like their own type, if they have one! ( ie- there doesn't appear to be a cargo door there!).
I wouldn't be at all surprised that there will be an accident report that will tell us the facts.
Happy flying.( to those that do!)
I think we need to realize where we are. We are in rumors and news. Not Planes49's private ground school. Oxygen tanks don't just ride around on -400 models. And of course there's going to be an accident report. I suggest you log off and wait for it if it's such a struggle to "fight" through posts you don't understand.
I'm reminded of the basics of free speech. I think we need to learn how to selectively read instead of trying to coerce others into putting up what we want to see posted.
Personally, I encounter a nugget like "joint" or "should keep there [sic] comments to themselves" and I just skip to the next post.
Thanks to the usual posters for putting up those fantastic photos and schematics. Makes this a highly entertaining and intriguing thread.
Last edited by pacplyer; 28th Jul 2008 at 05:25. Reason: better verb-age
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http://www.casa.gov.au/airworth/airw...7/B747-349.pdf
Boeing Special Attention Service Bulletin 747-35-2114 Revision 1
Maybe applicable... 