Qantas 744 Depressurisation [Archive] - Page 3

G-CPTN

28th Jul 2008, 00:38

Somewhile back someone stated that it wasn't 'possible' for a (vertically mounted) oxygen cylinder to break loose.
http://i337.photobucket.com/albums/n385/motidog/QF30-Cargo-Hold-03.jpg
indicates that the 'missing' cylinder was located 120 (cm?) rearwards of STA700 which can be seen on the left of this photograph:- http://cdn-www.airliners.net/aviation-photos/photos/0/5/8/0312850.jpg
Has anyone a photograph of a cylinder installation from edge-on (or even 'perspective') without the (sidewall) curtains?
http://i337.photobucket.com/albums/n385/motidog/QF30-Cargo-Hold-01.jpg
illustrates that there is a bracket fixed to the (curved) sidewall to support the cylinder.
Is it possible (even if not probable) for the oxygen cylinder to fall vertically should the bracket on which it sits break with the result that it falls onto the curved side of the fuselage and sits chafing the external skin weakening the structure (or maybe damages a previous weak patch) which then fails as the pressure outside falls.

In addition, above the 'missing cylinder' location is the door which was claimed to have the 'hole in the floor' (presumably caused by suction during the depressurisation through the hole in the fuselage structure).
http://www.theage.com.au/ffximage/2008/07/25/qantas2_wideweb__470x354,2.jpg

BTNH

28th Jul 2008, 00:45

Thanks for that! :ok:

lomapaseo

28th Jul 2008, 00:59

Has anyone a photograph of a cylinder installation from edge-on (or even 'perspective') without the (sidewall) curtains

Does this picture add anything?

What I worry about is the possible differences in configuration between the incident aircraft and the pictures.

If the picture is wrong I'll just delete it to avoid confusion.

deleted upon request

G-CPTN

28th Jul 2008, 01:15

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 . . .

Joetom

28th Jul 2008, 01:21

Look like water tanks maybe.....

Brian Abraham

28th Jul 2008, 01:23

Qantas has investigated the complaints from some pax that the system was not working correctly
More than likely a failure of the pax to listen to the brief or read the card where it says "pull to initiate oxygen flow".
Water tanks in the photo. Aft end of forward hold.

propmaker

28th Jul 2008, 01:24

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?

Nov71

28th Jul 2008, 01:25

Can someone explain how to post a .jpg photo in a reply please?

Deaf

28th Jul 2008, 01:28

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.

hetfield

28th Jul 2008, 01:29

@Nov71

Upload it here for example from your pc

ImageShack® - Image Hosting (http://www.imageshack.us/)

than copy and paste to the pprune image link.

cheers

llondel

28th Jul 2008, 01:42

Nov71:
O2 escaping at high pressure even from a slow leak, can create high temps (adiabatic )

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.

PJ2

28th Jul 2008, 02:00

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.

pattern_is_full

28th Jul 2008, 02:05

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.

G-CPTN

28th Jul 2008, 02:13

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:-
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.

rigpiggy

28th Jul 2008, 02:16

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

HotDog

28th Jul 2008, 02:16

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.:ok:

teaboy1

28th Jul 2008, 03:09

who was breathing what on the rapid decent!!!!!

rottenray

28th Jul 2008, 03:47

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?

pacplyer

28th Jul 2008, 03:52

Planes49 mumbled:
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!)

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. :rolleyes:

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. :ok:

SUB

28th Jul 2008, 04:03

Hotdog that photo is from a "D" chk, no big deal.

HotDog

28th Jul 2008, 04:32

Thanks SUB, it just looks so clean and new which made me think it came from the production line.

Aerolex

28th Jul 2008, 04:48

http://www.casa.gov.au/airworth/airwd/ADfiles/over/b747/B747-349.pdf

Boeing Special Attention Service Bulletin 747-35-2114 Revision 1

Maybe applicable... :confused:

11Fan

28th Jul 2008, 04:49

Hotdog,

Nope, they're a lot more shiny coming out of the barn.

wessex19

28th Jul 2008, 04:54

Apparently the flights captain, John Bartels wife had this to say about it on another web site as OZWITCH

Commwealth flying | Neptunus Lex (http://www.neptunuslex.com/2008/07/26/commwealth-flying/)

"You might not recall that my husband was ex-RAN A4. He now flies 747-400. He had the explosive decompression yesterday.

Fun day!

I can give your readers some facts that are solid:

No engines were shut down.
Aeroplane’s controls were unaffected.
Some computer functions and electrics were affected - all 3 ILS shut down and the Capt’s FMC. Antiskid warning came on.
The R2 door alarm activated.
Capt inititated controlled descent from 29K to 10K, which took about 4 mins. Mayday was called (John never ever thought he would have to declare a mayday in his entire career!)

After levelling off, fuel dump of 50 tons was commenced, and plane landed afterwards normally, but used all available runway. Engine #3 was shut down first, then 3 others after and plane was towed to terminal. Passengers disembarked normally via aerobridge.
John praised crew and passengers, who all rose to the occasion.

I have a few pics I can share if you’d like. Let me know, and if any other q’s

Ozwitch"

dj_lethal

28th Jul 2008, 05:07

http://i238.photobucket.com/albums/ff79/kurimaw1/untitled2.jpg

this is the section 42 of 747-400..(fairing attachment)

SUB

28th Jul 2008, 06:19

What about the 2 portable oxy bottles located just fwd of door 2r at the flight attendants seat ? They are in the usually mounted in a box just where the damage in the cabin sidewall was.

JG1

28th Jul 2008, 07:33

Tankengine

28th Jul 2008, 07:44

Most of us already have!:zzz:

Selfloading

28th Jul 2008, 08:30

Does the B744 Configuration Deviation List allow aircraft operation without the wing-to-fuselage fairing? If so, we can totally discount the part of the fairing in this incident and concentrate on what made the hole in the pressure hull.Dunno, is it not possible the the fairing did not come away in one piece but broke up, and in doing so punctured the pressure hull?

G-CPTN

28th Jul 2008, 08:55

Article from: The AustralianJuly 28, 2008 12:01am
QANTAS last night began inspecting oxygen bottles on its Boeing 747-400s after investigators found cylinder fragments embedded in luggage and the cargo hold ceiling of the jumbo jet involved in Friday's mid-air explosion near The Philippines.
While the Australian Transport Safety Bureau was refusing to rule out causes such as structural fatigue for a gaping hole in the Boeing 747-400, aviation sources said oxygen bottle failure was now at the top of investigators' list, The Australian reports.
Aviation sources said the force of the explosion near the base of the aircraft's right wing and underneath a door pushed up the passenger cabin floor as it tore through the metal hull.
They said there were two oxygen bottles in the area near the hole, and a failure was unprecedented.
ATSB spokesman Neville Blyth confirmed last night that a cylinder providing back-up oxygen was missing, but said it was too early to say whether this caused the explosion.

ExSp33db1rd

28th Jul 2008, 09:09

For interest. Early 707, supplementary oxygen bottle stowed on Flt. Deck rear wall near Flt. Eng. panel. Flt. Eng. hung his uniform cap on bottle, hat had plastic square inside to prevent hair grease staining the fabric which of course became greasy. O2 bottle valve had slight leak, hat caught fire, fortunately with no serious consequences. Doesn't help present problem but shall we wait for some FACTS now ? Thank you.

Rainboe

28th Jul 2008, 09:17

It's just a cacophany now, isn't it? Suddenly 100 amateur self-appointed accident investigators crawling out of the woodwork, leading the investigation. Horrifying. At least the 'struck by atmospheric re-entering Slazenger golf club' theory is now excluded! I never knew anybody with a keyboard could come across suddenly as a metallurgist/stress fracture expert. And we are supposed to read their 'analysis'?

pacplyer

28th Jul 2008, 09:25

Selfloading said:
Dunno, is it not possible the the fairing did not come away in one piece but broke up, and in doing so punctured the pressure hull?

Naaaaa. Had lots of fairings come off. They're plastic, composite, honeycombe, or thin sheetmetal affairs (or combinations.) Think flimsy. Think light. Think designed by Mr boeing not to be anchored into important structure without the fastner hardware designed to yield or strip free before it would be able to rip apart something as stout as a Frame or longitudinal stringer or spar.

What most SLF don't realize is that Goldfinger and Airport 77 are fiction. A small hole in the skin (if it doesn't break a crossbeam) probably isn't going to cause a rapid decompression. Conversely the 747 is not a boat; it is not water tight. In it's normal state, it is absolutely full of holes, leaks, seals hissing.....

Stick your hand down near a galley door. Chances are you'll feel it. Cold from the venturi effect of air escaping.

Sure, if it came loose, that fairing would flap around and maybe cause some little holes in the skin or screw up something else down stream when it disintegrated or possibly even go through an engine if you're real unlucky, but I can't see it causing that kind of damage.

IMHO, this is either a structural failure of the pressure vessel which took with it everything fastened to either side of the wall (O2 tanks and fairing)
- OR -
a structural failure of an oxygen tank that destroyed the integrity of the frame latticework.

Always suspect problems when engineers realize that the area has been previously repaired (as in this case.)

I give you as a case study, JAL Flight 123. The engineer who approved the repair committed suicide when it became obvious it was designed improperly.

Japan Airlines Flight 123 - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/JAL_flight_123)

Cause

The official cause of the crash according to the report published by the Japanese Aircraft and Railway Accidents Investigation Commission is as follows:
The aircraft was involved in a tailstrike incident at Osaka International Airport on June 2, 1978, which damaged the aircraft's rear pressure bulkhead.
The subsequent repair performed by the engineers was flawed. Boeing's procedures called for a doubler plate with two rows of rivets to cover up the damaged bulkhead, but the engineers fixing the aircraft used two doubler plates with only one row of rivets. This reduced the part's resistance to metal fatigue by 70%. According to the FAA, the one "doubler plate" which was specified for the job, (the FAA calls it a "splice plate" - essentially a patch), was cut into two pieces parallel to the stress crack it was intended to reinforce, "to make it fit".[10] This negated the effectiveness of one of the two rows of rivets. During the investigation Boeing calculated that this incorrect installation would fail after approximately 10,000 pressurizations; the aircraft accomplished 12,319 take-offs between the installation of the new plate and the final accident.
When the bulkhead gave way, the resulting explosive decompression ruptured the lines of all four hydraulic systems. With the aircraft's control surfaces disabled, the aircraft became uncontrollable.
[edit]Aftermath

The Japanese public's confidence in Japan Airlines took a dramatic downturn in the wake of the disaster, with passenger numbers on domestic routes dropping by one-third. Rumours persisted that Boeing had admitted fault to cover up shortcomings in the airline's inspection procedures and thus protect the reputation of a major customer.[4] In the months after the crash, domestic traffic decreased by as much as 25%. In 1986, for the first time in one decade, fewer passengers boarded JAL's overseas flights during New Years than the previous year.[11]
Without admitting liability, JAL paid 780 million yen to the victims' relatives in the form of "condolence money". Its president, Yasumoto Takagi, resigned, while a maintenance manager working for the company at Haneda committed suicide to "apologize" for the accident.[4]

Also there's this:

Safety Promotion Center - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Safety_Promotion_Center)

Section 41 and section 43 mods addressed known areas of weakness in the 747 design. The drawing supplied to us earlier in this thread is said by the poster to come from section 42.

These are all just my opinions; I am not an expert.

pac

Capt Kremin

28th Jul 2008, 09:34

Selfloading

28th Jul 2008, 09:43

Thanks for the informed and interesting reply pacplyer :ok:

bucket_and_spade

28th Jul 2008, 09:50

56 pages of pet theories/analysis without any official word!

At least Proon's consistent! ;)

Love it.

B&S :ok:

Goffee

28th Jul 2008, 10:19

According to an update on MSNBC (http://www.msnbc.msn.com/id/25867721/)- fragments have been found from a compressed air/oxy tank, specifically the valve, which makes the tank look increasingly like the prime suspect.

Expect the fax machine in your local maintenance office to start churning soon.

sevenstrokeroll

28th Jul 2008, 10:21

interesting bit posted by wife of pilot...if true.

ILS out? is the glideslope antenna in the vicinity of the damage?

blow.n.gasket

28th Jul 2008, 10:47

Was it one of those new composite bottles?
You know the weight saving ones that were being trialed.

Blacksheep

28th Jul 2008, 11:10

The informed discussion on this is taking place in the Dunnunda forum. Pieces of the pax oxy bottle have been found inside the main cabin. They entered the main cabin via the hole that pieces of the bottle punched through the floor at R2. The bottle was apparently six months old.There you go. The facts are slowly unwinding... ;)

Now all we need to know is what initiated the first ever recorded occurrence of an aircraft oxygen cylinder exploding in flight. I'm jiggered if I can think of any initiators off-hand. We can certainly discount maniac firearm owners who want to see "what happens if" like the chaps on You Tube. :confused:

Obie

28th Jul 2008, 11:16

Well, I'd be more than happy to see the pictures the wife has!

Vertiginous

28th Jul 2008, 12:31

‘O2 escaping at high pressure even from a slow leak, can create high temps (adiabatic ) The presence of a small amount of oil/grease can cause ignition’

Sorry, but you're wrong on this point. Adiabatic expansion (and compression) is a system that applies to confined gases that remain confined throughout the process. Escaping gas is not an adiabatic system. Adiabatic compression makes the gas hot, with no loss of heat to the surroundings; adiabatic expansion sees the gas cooling, but again with no heat transfer.

What we have here is the question of escaping gas, which has nothing to do with an adiabatic system. When you release a CO2 fire extinguisher — the cannister and contents being at ambient temp — the gas that emerges is very cold. This is what happens when any compressed gas is allowed to expand rapidly. The gas absorbs a great deal of heat from the surroundings. The warnings on BOC cylinders are about the danger of combustion in the presence of O2.

Vertiginous

28th Jul 2008, 12:36

Vertiginous

28th Jul 2008, 12:55

‘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.

wrenchbender

28th Jul 2008, 13:48

"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.

forget

28th Jul 2008, 13:52

Nope. Glideslope & Localizer antenna are located under the weather radar radome and embedded in the Nose Landing Gear doors.

And what about the co-axial feeders?

wrenchbender

28th Jul 2008, 14:02

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...

Troy McClure

28th Jul 2008, 16:01

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?

BOAC73

28th Jul 2008, 16:51

....must remember to take those 3ft body fairing panel fasteners out of my toolbox!!
B73

Litebulbs

28th Jul 2008, 17:06

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!

BOAC73

28th Jul 2008, 17:09

.....I never mentioned the need for the decal!
B73

Litebulbs

28th Jul 2008, 17:17

Don't worry, I am firmly in the 100 mile brigade!

glhcarl

28th Jul 2008, 18:18

‘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.

The lap joints are bonded as will as riveted, so a lap joint has more than twice the tensile strength as the skin alone.

BOAC73

28th Jul 2008, 18:33

Not if it is compromised by a poor bonding process.
B73

beachfront71

28th Jul 2008, 18:44

Valve in oxygen cylinder the culprit in 747 explosion | theage.com.au (http://www.theage.com.au/national/valve-in-oxygen-cylinder-the-culprit-in-747-explosion-20080728-3maq.html)

Vertiginous

28th Jul 2008, 19:22

‘The lap joints are bonded as will as riveted, so a lap joint has more than twice the tensile strength as the skin alone.’

Apologies. An important point.

lomapaseo

28th Jul 2008, 19:31

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)

wrenchbender

28th Jul 2008, 19:36

The missing cylinder was mounted in a vertical orientation.

broadreach

28th Jul 2008, 19:50

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! :rolleyes:

chris weston

28th Jul 2008, 19:51

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

vortsa

28th Jul 2008, 20:09

OK if we have established that the oxygen cylinder did fail piece of cylinder found embedded [understand not fragments of cylinder but parts from the regulator] then what was the reason for its failure. a reasonably new bottle 6 months 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.

Intruder

28th Jul 2008, 20:41

then what was the reason for its failure.
Maybe the answer lies somewhere in the Australian CASA's issuance of an AD for "certain oxygen cylinder supports"! It is certainly within the realm of credibility that a failed bracket caused part of an O2 bottle to wear against the structure and eventually caused a rupture of a line, valve, or bottle...

TWT

28th Jul 2008, 20:46

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.

The spokeswoman is referring to a different incident involving a 738 not the 744 which is the subject of this thread

TWT

28th Jul 2008, 20:56

Maybe the answer lies somewhere in the Australian CASA's issuance of an AD for "certain oxygen cylinder supports"!

That AD was issued by the FAA and it concerned the crew oxy bottles,not the passenger bottles.Not in the same location and was addressed by Qantas earlier this year.Has been discussed earlier in this thread

lomapaseo

28th Jul 2008, 21:27

Well here we are several days later and we still don't know the chicken from the egg, but the roost should be getting a lot of attention.

I still enjoy this thread though as long as we can get a confirmed fact and better understanding in a few threads.

I still don't know what the deal is about shards of an Oxygen bottle being found. What does the words "shards" refer? Is this only the valve which could be entirely secondary as it worked it's way out?

Midland63

28th Jul 2008, 21:29

SLF with no aviation industry involvement

Am I the only one who thinks the Captain's wife's posting on another blog alluded to above doesn't ring very true?

Unless Mrs Bartels is also an airline pilot, he seems to have regaled it all to her in an extraordinary amount of techie detail and moreover she seems to have remembered all the detail (for e.g. it was 50 tons of fuel dumped, it was the R2 door alarm which activated).

So either it was Cpt B himself who wrote this or it's just another wind up.

What do you pro's think?

If it is genuine, can the professionals draw any clues - e.g. positioning of Antiskid warning circuitry relative to oxygen bottles and holes in fuselage etc.

M63

broadreach

28th Jul 2008, 21:34

TWT
Oops, and thanks.

Litebulbs

28th Jul 2008, 21:39

Well, that is a new one. A repeat inspection for O2 quantity checking? I am not talking about daily/weekly, but more of an out of phase or MEL requirement. A bit iffy that?! I can imagine why though. We were reminiscing last night, as you do?! and I recalled the time when, as an apprentice, we spent all week on a B747, trying to get the pax oxy ring main to stop leaking. It is a big system.

If you were fault finding, you would imagine the fault to be within the cabin or flight deck, because this is the most probable place of a system disturbance. If you use an oxy charging point, as it appears QANTAS do, you would imagine that the last place the leak could be, would be on the bottle. If it had been changed recently, you would check it, but if not, you would be looking at flight deck masks, or passenger O2 PSU's with a bottle of snoop in your hand.

I still can't work out how the bottle let go though. The regulator valve yes, but bits of bottle?

NAPIER10

28th Jul 2008, 21:52

If the incorrect length fastener , ie too long is installed it will only puncture or push off the sealed anchor nut and not rub on any structure and will still secure the fairing and could cause a minor pressure leak.

TWT

28th Jul 2008, 22:01

Oops, and thanks

The 'other incident' involved a 767 (VH-OGK),not a 738 so I was incorrect too :)

Machaca

28th Jul 2008, 22:06

An example of cylinder rupture fragments:

http://i337.photobucket.com/albums/n385/motidog/Cyl-frag32.jpg

Badgeman

28th Jul 2008, 22:13

Midland63, if you can find any samples of Pilot B's typing from before and see if there are any trends or patterns that are similar to his "wife's", then it's him. In a completely other forum I belong to we busted a con-artist by checking the typing his "wife" was doing on the forum while "she" claimed he was hospitalized.

"all the sentences would just ramble on, there were never any capitol letters, the sentences would always end with commas, never a period," ;)

Thus we concluded his "wife" had never keyed a single post to the forum while he was "hospitalized". It was him the whole time.

llondel

28th Jul 2008, 22:32

Litebulbs:
I still can't work out how the bottle let go though. The regulator valve yes, but bits of bottle?

If there was a manufacturing defect (such as a wall void) in the bottle (there's mention somewhere in the thread that it was quite new) then it could have required a few cycles to crack and then split. If it propagated the crack to the valve end early enough then the valve could have been ejected quite forcefully as the bottle broke.

However, if it was such a defect, serious questions would need to be asked of the manufacturing and testing process that let it through.

How are these bottles tested, and how often?

Litebulbs

28th Jul 2008, 22:49

I don't know anything about composite bottles of the size that would be used on a -400. We use a composite bottle for passenger assist, but our crew portable bottles are still cast (iron) alloy. Heavy and robust. Our recharge bottles again are cast and robust. They need to be, when they are being shipped around. They get a fair bashing around.

Again, we were talking last night about O2 bottles. My mate was telling me about a bottle that had a regulator knocked off in a hanger where he was working. It went off like a torpedo, but the bottle stayed intact.

soem dood

28th Jul 2008, 22:59

"How and how often often are these cylinders tested?

Hydrostatic testing. Test interval per spec in table, i.e. every 3 to 5 years:

CASP H-Test Info (http://www.caspaerospace.com/CASP%20htestinfo.htm)

Litebulbs

28th Jul 2008, 23:05

If we run a crew portable bottle below 1/4 full (500psi), then we are not allowed to recharge it, it must be sent off for a shop overhaul/test/replenish.

lowerlobe

28th Jul 2008, 23:07

Fortunately there appear to have been no cabin crew working in that galley at the time
....I think you mean that the galley operator was not in 'THAT' section of the galley at the time.From the video footage a pax took it looks as though the incident happened during a meal service and a crew member would have almost certainly been in the galley close to R2 at the time.

I imagine that all crew when looking at work positions for other flights will now be wondering whether or not it is wise to work in that galley until the answer is found.....

Milt

28th Jul 2008, 23:17

Anyone know whether any persons on board suffered ruptured ear drums?

Those with blocked eustachin ? tubes will have suffered somewhat..

Oh and what alloy is used to make oxy bottles?

Duck Rogers

28th Jul 2008, 23:26

Folks.

These last days have seen us deleting dozens of posts in an attempt at keeping threads on track, something most of the professional members here say they want. So please, can we keep to the subject in hand?

Humour mixed in with an informative post is fine but anything else is just the thin end of the wedge leading to conspiracy theories, diving bottles and anything else the MS FlightSim brigade want to throw in.

You can't ask us to keep this forum professional and then instigate the rot by posting nonsense.

Thanks

Duck

r75

28th Jul 2008, 23:39

Well said that man, lets wait and see what the investigations turn up...and I work 747-400s as an L.A.E.

pacplyer

28th Jul 2008, 23:48

Great post Vortsa,

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.

Thanks for that.

How is the bottle internal corrosion check accomplished? Bora-scope check? Chinese eyeball? Is the inside straight steel or primer?

So a diligent tech would note a [way out reading] of flat (or say, less than 200psi) pressure on the [individual bottle] and not simply re-service it, but have it removed since it inhaled humid air? Is that right? Schedule it to be re-inspected?

Then corrosion takes how long? A week? This mistake happens every month for six months at out stations and Boom?

Sounds like this aircraft was a "leaker" which is not all that uncommon in my experience.

Litebulbs

28th Jul 2008, 23:54

On the Boeing's that I work on now and for crew O2, not pax, the minimum dispatch is 1300psi, so the bottle or bottles would never get to 200 psi. This would be picked up by the engineers or operating crew prior to departure, unless this baby had a serious problem.

pacplyer

29th Jul 2008, 00:10

Yeah bulbs,

That's what I'm talking about; a serious leaker. I've walked onboard and found mechanics engrossed in exactly that: leak isolation that delayed departure. The next station was telexed to watch it when it sat overnight, and a logbook sticker to check pressure was issued.

I've also walked on board a/c that were way low, even though the service check was completed just a few hours prior.....

Mr. Murph says gas can escape. When it is way low what is prudent? Tank exchange?

Weapons_Hot

29th Jul 2008, 00:20

I have viewed the posts to this this thread. Many have been informative, albeit speculative, as to what occurred on the subject flight. Generally, I have been both informed and educated as to what, why, when, how, and (lesser importance) who.
Many, in their posts have considered their view to be "fact", when in fact, there was a lack of fact.
One poster in his many posts has considered this domain, to be the sole domain of "professionals" and should, upon his insistence, banish any one less perfect/"professional" (sic?) than he.
Now I see that the "Moderator" is deleting posts considered by him/her not to be worthy/relevant to this thread. This in itself smacks either of intolerance or secular interests; both a bane on free speech, and certainly manifested by "Removed by Moderator".
Perhaps it is time for the Moderator to exercise moderation.
I say: let everyone have his/her say. I can easily sort "chaff from wheat", but let me first have a full bushel.

hogey74

29th Jul 2008, 00:39

1. Yeah - I wondered if it was one of the ugly sisters too. Apparently from Malaysian and took over a year to iron out all the "squawks" after purchase. Mainly though I heard they have lower rated engines than other -400s so runways apparently look shorter from the pointy end on take off! :)
2. Re censorship of forums - agree that getting the full drum is better but I haven't been around here long enough to know what is likely to be "moderated" - might be offensive or unhelpfully negative stuff maybe?
3. I was unimpressed with the reporting on this incident, even on ABC (Australia) and wrote to ABC about it. They actually have run my email on their online opinion page and you can read it here if you care...

Opinion. ABC News Online (http://www.abc.net.au/news/opinion/emails/)

Dunno how long they stay up but it went up this morning, 29th July 08. I am an enthusiast and a mature-age student pilot on a 150 hour course so sorry to any pros who don't agree with my email - tried to keep it as factual as my experience allows. cheer John

uncle_maxwell

29th Jul 2008, 00:39

Not a professional pilot (yet). Not an engineer either. A few thoughts straight from the armchair at the risk of being censored out of hand by the totalitarian 20,000-hour-on-type forum masters…

Given all previous facts, info & speculation, what would your recommendations be for systems and procedural improvement?

Here a few shots from the hip - some (or many?) of which were mentioned before:

A. Systems Design
1. Location of onboard bombs: Can anyone clarify why pressurised bottles (apart from fire extinguishers & mobile O2 for crew) would knowingly/willingly be kept in the pressure vessel? Is it feasible to carry them on the a/c outside the pressure compartment such that depressurisation or structural damage are unlikely if they fail?
2. O2 for crew:
- There should be 2 indicators for each pilot: one indicating flow (and pressure) and the other indicating content (O2 vs. nitrogen for Qantas I guess, but you could have other contaminants as we know from scuba/technical diving).
- There should be at least one independent back-up: mobile O2 bottle for each pilot within reach of their seats if everything else fails. Again, look at scuba divers. They actually have several back-ups (Main bottle(s): regulator 1, regulator 2, some 3rd regulator; buddy: 1 or 2 spares plus buddy’s main to share; separate independent bottle as last resort giving a few minutes or if buddy is MIA. Yes they take compressed air or nitrox instead of O2 but principle is the same.)
- O2 for crew seems to have failed in previous emergencies. (1st officer on BA w/ 4 engines out due to volcanic ash – any others from the old folks?)
3. O2 for pax:
- Systems need to be designed such that pax need to do nothing apart from putting masks on. If they need to pull to trigger generator, 95% will not know or have forgotten and 5% will pull so hard that the hose separates from the system.

B. Procedures Design
1. Depressurisation crew: Great potential for refinement I think. IMHO the item ‘Establish communication’ is grand BS and wastes precious time. What if PF does not get mask working or O2 flowing? What if both pilots don’t? Their best course of action would still be to initiate immediate descent (possibly at a speed assuming structural failure) – with or without communication. Unless they have an O2 back-up in reach. But maybe not even in that case. Procedures should generally assume that 1st O2 supply does not work and comms cannot be established. How about using hand signs? What about an emergency descent button on the flight control deck that will do exactly that (taking into account GPWS and TCAS)?
2. Ground checks: Good scuba divers check their regulators/air flow/bottle pressure&contents 3 times: once when setting up their systems, once when putting them on, once when doing buddy checks. How come airline crew forget or only do it once?
3. Pax briefing: If strap has to be pulled on rubber jungle than it must be emphasised. (“Pull on strap until you feel flow or you will die.”) Also it has to be shown how hard to pull. Better to eliminate that necessity altogether as above. As mentioned by others before, the rapid descent should be described as standard emergency procedure in briefing.

Corrections & your own additions appreciated! We can then compare the pprune wish list with what the ATSB come up… ;)

Happy landings!

Litebulbs

29th Jul 2008, 00:42

Pacplyer,

It was a long distant memory trying to chase leaks on a B747. It is hard enough finding them on a B757! I would fire toolbox up now, to look for leak rates, but if any of my mates were reading this thread from work, it would be the biggest flame in history on my return!

I was called back to top up crew O2 the other day, that was 80psi above min dispatch, because of the possibility of flying over high terrain, so I find it hard that QANTAS would release a leaky aircraft on a long sector. Unless, because of the leak, they filled the tanks upto max. In my previous life, 1750 to 1800psi was max and now we will top up at 1300ish to about 1700psi. If they had a known problem and it was on a long sector, you would be inclined to get as much as you could in, which, if there was a problem somewhere in the system, would increase the chance of a failure to a weak point.

I still find it hard to believe that a bottle would let go without some external force, other than dropping from its mount, influencing a rupture of the bottle.

As I have said before, they are solid lumps!

******DISCLAIMER******** something within the cargo pallet went off and through the sidewall panel, hit the bottle/regulator at speed and caused the rupture.*********SPECULATION OVER**********

pacplyer

29th Jul 2008, 00:56

Great post Litebulbs, and thanks.

I was called back to top up crew O2 the other day, that was 80psi above min dispatch, because of the possibility of flying over high terrain, so I find it hard that QANTAS would release a leaky aircraft on a long sector. Unless, because of the leak, they filled the tanks upto max. In my previous life, 1750 to 1800psi was max and now we will top up at 1300ish to about 1700psi. If they had a known problem and it was on a long sector, you would be inclined to get as much as you could in, which, if there was a problem somewhere in the system, would increase the chance of a failure to a weak point.

I still find it hard to believe that a bottle would let go without some external force, other than dropping from its mount, influencing a rupture of the bottle.

As I have said before, they are solid lumps!

******DISCLAIMER******** something within the cargo pallet went off and through the sidewall panel, hit the bottle/regulator at speed and caused the rupture.*********SPECULATION OVER**********

My thoughts exactly, this one's a real head-banger. Bulbs, I was just speaking hypothetically. I'm sure Qantas is not going to dispatch a bad leaker on a long segment. But assuming that leak rates will remain constant is an iffy business. :confused: We did the same thing with "oil burner" engines. Put an extention pipe on the oil fill so that the sucker wouldn't run out of oil before getting there!

Could one of you SLF's check and google NTSB oxygen bottle accidents for me? I don't think it's ever happened. Do something useful for a change while Vortas and Bulbs think about this some more....

bubbers44

29th Jul 2008, 01:56

Uncle M, I have been in an emergency descent when I was a copilot on a B737 with a cracked windshield. The captain started an emergency descent between SFO and LAX from FL330 to FL240 but had initiated it before I got my mask on. He tried to talk to me through the interphone but when he pulled his oxygen mask down he pulled out the mike jack. The communicate part was done by taking my mask off to tell him what I was doing getting the descent clearance and shutting off the windshield heat that was arcing and adjusting standby pressurisation. It was an outer pane so the checklist said no restrictions, maintain 250 knots max below 10,000 ft. I guaranty you no pilot is going to maintain level flight in an explosive depressurisation if communications can't be established. The FAA likes to make everything just like you would do in a simulator.

paulg

29th Jul 2008, 02:03

Yes Pacplyer. Have googled NTSB Oxygen Bottle Accdents as directed. Nothing relevant found. :)

treblemaker

29th Jul 2008, 02:09

SLF, but engineer in an unrelated field -- means I see some interesting clues that have not been assembled in one post yet.

Perhaps I may not accurately recall what I have seen in the past 500 or so posts, so feel free to correct. But I think I've seen the following claims:
If valve is detached from the bottle, the bottle is unlikely to have room to accelerate enough to have sufficient momentum to puncture the hull.
Escaping O2 will be quite cold due to the expansion from extreme high pressure in the bottle.
Passenger O2 bottles are mounted inverted (valve at the bottom) (This is the one of which I'm most unsure. Of course now as I search back through the thread I cannot find this)
Therefore very cold, high-speed gas will be impinging on the inward-curving fuselage below the bottle mounting.Would the Aluminum alloys used in the frame and skin tend to become brittle, and therefore weaker, at extreme cold temperatures that might be produced by the expanding gas?
Best Regards,
T.

scuppy1

29th Jul 2008, 02:21

i work for qantas it was vh-ojk

ampclamp

29th Jul 2008, 02:28

Plenty of oxy systems leak.Never seen bottle explode (until now maybe) If there was no sign of fire it sounds like a rupture/mech cylinder failure.
Blown the reg out of the end of it or a cracked cylinder serhaps?

I've avoided endless speculation but given they've found bits and pieces it seems pretty clear, it just remains as to why.

If a leak is noted ie more px drop than what would be expected or a history of too regular top ups it must be investigated.

There are no allowable leaks that I am aware of.

Sure gas escapes over time, it must, but real leaks are no go.

I'd say that 98% or more of leaks are the lines, joins, and charge fittings an maybe 2% or less regulator on the bottle.Never seen a leaky bottle ever.Just my experience speaking, others may have differing view.

Testing around 5 years hydrostatic that is depending if regulator or hydro date expires first.Not sure what internal inspections are carried out or if cylinders are x-rayed or other NDT carried out.

I have seen oxy bottles rejected for fitment by LAME's due to scratching or scores in the cylinder wall ex stores.

The cylinder in question may have been dropped or knocked hard to precipitate a failure long term.Not necessarily in service either.Transport, stores, overhaul are all possible areas.

I just hope there are enough clues not at the bottom of the sea to get a grip on the cause.

Annulus Filler

29th Jul 2008, 03:03

Food for thought.

1. Did the decompression passenger announcement trigger?

2. Why were the passenger video screens still running after the descent as shown by amateur video?

3. Passengers have reported there was no oxygen supply to their masks. Then how did the passenger oxygen masks deploy?

sevenstrokeroll

29th Jul 2008, 03:38

some oxygen masks require the passenger to tug on the line to pull out the guarding pin.

if you listen during the safety briefing, you know this.

and anyone who is looking for their passport instead of keeping their oxygen mask on their face has an odd set of priority.

Semper Amictus

29th Jul 2008, 03:40

<3. Passengers have reported there was no oxygen supply to their masks. Then how did the passenger oxygen masks deploy?>

It is quite possible that they didn't hear (or chose to ignore) the bits in the safety briefing about :

'Pull the mask down to turn on the oxygen supply'

and

'Note that the mask does not inflate'

If they didn't pull them down firmly, no oxygen.
If they didn't see the transparent 'balloon' bit inflating, perceived lack of oxygen !

74tweaker

29th Jul 2008, 03:53

Passenger masks are deployed automatically by an aneroid switch in the cabin ceiling. Once the cabin altitude climbs through a preset limit (on the 767 it's 14,000 feet) the switch activates and drops the masks. Should the switch fail or the captain think it's warrented - the crew can deploy the masks by pushing a switch in the cockpit.

Now - some people didn't get oxygen probably because 1 bottle was missing and I WOULD GUESS at least some of the other bottles and parts of the system were most likely damaged.

It has been confirmed by investigators that the #4 O2 bottle was missing and that pieces of it were found in the aircraft. One piece, identified as part of the valve assy, was found in the passenger cabin after making a 20cm hole in the floor.

They still don't know if this was a cause or after effect.

chris.dever

29th Jul 2008, 03:54

In one of the (hundreds of) previous posts was a quote from a SLF stating that passengers put their passports in their pocket in case of a crash! :sad:

ZAGORFLY

29th Jul 2008, 03:57

A gas bottled explosion? I'm doubt, too little damage, but also can't be a rocket..

BTW can somebody kindly expalin me haw simply post a photo ? I have one quite interesting about the location of the Oxygen Bottles in the A 330 ER.

regards

ampclamp

29th Jul 2008, 05:22

Too little damage? you are kidding surely? If they've found the reg in the cabin (via the floor) and bits elsewhere I think the cylinder letting go has a fair bit of credibility.
Having a filthy great hole in your fuselage without signs of fire or explosives gives the cylinder theory more weight.

ampclamp

29th Jul 2008, 05:30

Luv the nick AF.
I would guess the altitude s/w worked as advertised, deployed the masks set off the emerg announcements.Having gone less than trip altitude (11,000 to maybe 13,000 ft) or there-abouts the s/w likely reset to normal and PES prob back to normal also.

Pax complaining of no oxy may expect a gushing air supply in their faces, not pulled the lanyard or indeed not had any due to nil supply from non existent cylinder or low flow due to rupture.
We'll find out soon enough.

Wingover68

29th Jul 2008, 06:51

Qantas Boeing 747-400 accident and diversion to Manila on 25 July 2008

29 July 2008

A media conference discussing the progress of the investigation into the circumstances surrounding the Qantas Boeing 747-400 depressurisation and diversion to Manila on 25 July 2008 will be held in Manila today, Tuesday 29 July 2008.
Where: Lufthansa Technik Offices Boardroom, Manila Airport
Time: 2:00 pm Manila time, (4:00 pm AEST)
Mr Neville Blyth, Investigator in Charge (IIC) will discuss factual information known to the investigation team at this time and will outline the investigation process.
Any person/witness with information about the accident is encouraged to contact the ATSB at [email protected]
No further media briefings will be conducted by the on-site team. After this briefing, all media enquiries must be directed to the media contact listed below.
Media Contact: George Nadal

NSEU

29th Jul 2008, 07:05

The daily rags just keep getting worse....

Today, the Daily Telegraph used the pics of the potable water bottles in Post #521 to show what oxygen bottles look like! No doubt, I could have posted a pic of a fire bottles and they wouldn't have known any better :}

Here's a typical installation of passenger bottles in the right hand sidewall of the Forward Cargo (looking slightly towards the aft of the aircraft).

http://members.ozemail.com.au/~b744er/SidewallO2PaxBottles.jpg

As mentioned previously, the 4th bottle along "gave way".

Rumour has it that half (exact percentage not known) the bottle went up through the cargo ceiling (into the cabin), and the other half went through the side of the fuselage.

The tech crew bottles are mounted horizontally, forward of the pax bottles (adjacent to the cargo door). The cargo fire bottles are mounted aft of the last bottle shown here (behind the panel labelled "5".
There are six more passenger bottles mounted in the cargo ceiling on this particular aircraft.

On this particular aircraft, the fabric panels are secured with press studs and velcro. These are shown hanging down. The ceiling panels are zippered and have velcro.

The bottles shown here are not of the Aluminium/Kevlar variety. They appeared to be of the steel(?) type

Regarding the comments about the ILS.... The Localiser system uses the VOR antenna on the top of the vertical stabiliser (fin) until LOCaliser or APProach mode is selected on the Autopilot Mode Control Panel. The coaxial cables must run down the fuselage somehow, but, from memory, I don't know if they run in the ceiling or in the sidewalls. I have seen quite a few coaxes in the ceiling, but they could have been HF.

Rgds.
NSEU

Annulus Filler

29th Jul 2008, 07:07

Can anyone confirm that the decompression passenger safety announcement was activated?

NSEU

29th Jul 2008, 07:23

Can anyone confirm that the decompression passenger safety announcement was activated?

I can't, but I can tell you that on this aircraft, the announcement is triggered by a pressure sensor in one of the flow control units (seen between bottles #2 and #3.. looking left to right in the picture above). When the oxygen starts flowing, the pressure sensor circuit triggers the announcement (plus a lot of other things)

Rgds.
NSEU

Wingover68

29th Jul 2008, 07:36

MEDIA RELEASE

Adjust font size:
http://www.atsb.gov.au/images/DOTARS_fs_off_01.gif (http://www.atsb.gov.au/newsroom/2008/release/2008_26.aspx) http://www.atsb.gov.au/images/DOTARS_fs_on_02.gif (http://www.atsb.gov.au/newsroom/2008/release/2008_26.aspx) http://www.atsb.gov.au/images/DOTARS_fs_off_03.gif (http://www.atsb.gov.au/newsroom/2008/release/2008_26.aspx) http://www.atsb.gov.au/images/DOTARS_fs_off_04.gif (http://www.atsb.gov.au/newsroom/2008/release/2008_26.aspx)

2008/26

Investigation into Boeing 747- 400 depressurisation and diversion to Manila, Philippines

29 July 2008

The ATSB is leading this safety investigation with the assistance of a number of other organisations and agencies, including the Civil Aviation Authority of the Philippines, The National Transportation Safety Board and the Federal Aviation Administration of the USA, the Civil Aviation Safety Authority of Australia and Qantas and Boeing.
Yesterday the aircraft was moved to a hangar. This will provide a safer and more optimal working environment for the investigation team.
The remainder of the freight on the aircraft has been progressively examined and removed from around the area of the rupture. This has allowed the investigation team full access to the area. The team have also been examining and clearing the area adjacent to the disrupted right cabin door.
The investigation team are in the process of examining the interior of the cabin including the onboard oxygen system, the passenger masks and portable crew oxygen cylinders. The aircraft outer panels around the ruptured area have also been removed.
A number of components and parts of components are being retained for further examination and analysis at the ATSB engineering facilities in Canberra.
Last night the aircraft cockpit voice recorder (CVR), which records crew conversations, radio traffic and cockpit ambient sounds, was downloaded by ATSB specialists in Canberra. Unfortunately, the standard two hour recording which works on an endless loop principle did not contain the event. The oldest recording commences after the descent and diversion into Manila, so the event itself appears to have been overwritten. However, the information that has been captured on the CVR may provide valuable insights into the flight crews handling of the situation following the depressurisation.
The aircraft flight data recorder (FDR), which nominally records 25 hours of data, is being downloaded today at the ATSB Canberra facilities. The specialist team should know in the next day or two if the recording contains valid data.
The investigation team plan to continue the examination and collection of evidence from the aircraft. ATSB investigators in Australia are gathering data from the operator. Interviews with both flight crew and cabin crew are being conducted today in Melbourne.
A reminder that the ATSB requests that any passengers that experienced issues during the flight, or those who photographed or videoed the incident, contacts us via email at [email protected]

vortex738

29th Jul 2008, 08:47

No , Tearstoppers in Boeing fuselage frames prevent crack failure progression. This is indicative of catastropic failure of a type expected with pressure vessel internal weakness and or non crystalline metal structure i.e. fatigue related or manufacture deficient. Probably undetectable at time of manufacture. Would be good to retrieve the errant green pill.:hmm:

cambruzzo

29th Jul 2008, 09:16

Interesting that ABC and News Radio are silent on the ATSB release.

They have been canning QF all day, added to by the ADL return last night.

Perhaps they don't want to hear the real story as it is not spectacular enough?

Perhaps they will report on the 737ER over the Himilayas instead

Buster Hyman

29th Jul 2008, 09:44

My Brother in Law has been called almost every day by a QF representative. They are making counselling available for those who need it.

He has also been informed that the full cost of his airfare will be refunded & he will be issued a free ticket to the tune of the same amount. I suggested that when the calls stop, he start the litigation!:p

PS. To all the Journo's that contacted me (who all clearly identified themselves...thank you) I have asked if he wished to speak to the media, but he has declined.

Trackmaster

29th Jul 2008, 10:51

Buster
As a long time squatter, I have finally been stung into action.
I sincerely trust you are trying a little bit of humour regarding the litigation.
QANTAS has obviously been trying in regard to your Brother in Law, if you can be believed. Part of a well rehearsed incident management plan.
What would the litigation involve.?..failure to drive him into the South China Sea at high speed so that his family could sue for even more?
Gotta be a buck in that.
:mad:

Blacksheep

29th Jul 2008, 10:52

Interesting Media Release. No mention of exploded aircraft oxygen cylinders or shrapnel in the aircraft cabin, only that they are examining the oxygen systems and they have retained some components and "parts of components". They do mention the area around the "disrupted right cabin door" but they don't say in what way it is "disrupted" - though we may surmise.

I'm still aghast at the problems an unprecedented exploding oxygen cylinder would bring to our industry. No doubt the investigators are too, which is probably why they're holding their peace.

Meanwhile we who will have to pick up the pieces as it were, and deal with the aftermath, can carry on trying to puzzle out how a cylinder that was firmly installed in its bracket in a secure location, (for six months according to one post) could suddenly and spontaneously burst.

WTF? :confused:

Capt Kremin

29th Jul 2008, 11:01

Guys, as I told you. It was an exploding oxygen cylinder, and unless there was some dodgy handling of the cylinder by QF staff at the installation or maintenance stage, (unlikely at this time) then the upshot of this event should not be a dimunition of the reputation of QF's operational standards, rather, the complete opposite.
I believe QF were the unlucky recipients of a one off event, completely out of their control, and that the crew handled it with aplomb. Time will tell if I am correct..

Buster Hyman

29th Jul 2008, 11:05

Trackmaster. As a long time squatter, if you can be believed, it would pay to learn what this - :p - smilie means...

forget

29th Jul 2008, 11:09

I believe QF were the unlucky recipients of a one off event, completely out of their control, and that the crew handled it with aplomb. Time will tell if I am correct..

I'm guessing you're right. And I do hope you're right.

Noddys car

29th Jul 2008, 12:26

Understand HAECO dispatched VH-OJK that morning under the MEL for a crew oxy indication fault.

LapSap

29th Jul 2008, 12:33

Probably fortunate they weren't at their initial flight planned level of 330 either.

Jets on

29th Jul 2008, 12:35

If the oxygen bottle assembly was only fitted to the aircraft 6 months ago, then who overhauled it and did QANTAS trained engineers fit it or were they contractors working for QANTAS. I ask this as a lot of QF people are under pressure at the moment.
As a previous post stated, if any problem occurs in flight I’d want a QANTAS crew working the problem through. Again, well done Tech and Cabin crew.:D

vortsa

29th Jul 2008, 12:39

Aircraft had been flying under that MEL for max 10 days,...... we are getting closer to the truth ..... keep searching the truth is out there.

Just need to start connecting the dots now..... or have they already done that and need more time before telling the world what actually happened?

Some people may have to be protected first???

Noddys car

29th Jul 2008, 12:46

http://img294.imageshack.us/img294/9103/dsc02332fi5.jpg

Can clearly see the missing bottle location

beamender99

29th Jul 2008, 12:49

Rumour has it that half (exact percentage not known) the bottle went up through the cargo ceiling (into the cabin), and the other half went through the side of the fuselage.

From a SLF view of the many postings.

Can someone pull together the main aspects of the event?

Many have expressed what happens if a valve is knocked off and you get a cylinder acting like a rocket.

Many have at length observed that if the cylinder exploded then there appears little shrapnel type damage in the area.

Am I to surmise that bits of the valve etc went upwards and the whole intact cylinder popped out through the hull and took the fairing with it?

The latest press release does not say much to add to understanding what happened.

Jets on

29th Jul 2008, 12:49

Are QANTAS aircraft flying around with MEL’s that they don’t have personnel or time to rectify. Operating with MEL’s is still operating within the maintenance limits allowed, isn't.

Fargoo

29th Jul 2008, 12:51

http://img294.imageshack.us/img294/9103/dsc02332fi5.jpg

A picture that really does says 1000 words :ok:

Great find Noddy.

Noddys car

29th Jul 2008, 13:00

Look closely at the end of the connector towards middle of photo, Looks like evidence of burning

http://img65.imageshack.us/img65/49/dsc023391sq0.jpg

Re-Heat

29th Jul 2008, 13:01

If the oxygen bottle assembly was only fitted to the aircraft 6 months ago, then who overhauled it and did QANTAS trained engineers fit it or were they contractors working for QANTAS. I ask this as a lot of QF people are under pressure at the moment.

It is irrelevant whether contractors or Qantas did it - the only thing that matters is whether they did it to appropriate Qantas standards (or not).

I hardly think anyone wants this thread to turn into irrelevant union-instigated contractor-bashing, so why not start up another thread if you want to go there?

Jets on

29th Jul 2008, 13:50

Re-Heat
Sorry if I have offended anyone. But as you stated "as long as it was done to Qantas standards" and that is relevant. I have only heard of an oxygen bottle exploding during charging or through contamination with oil, not while stored. And if this forum has speculated that it was an oxygen problem that led to the hull failure then it would be relevant to find out if incorrect installation was a root cause, and if so by whom. QANTAS is now a global company with maintenance done in many countries. Nothing to do with bashing anyone.

LapSap

29th Jul 2008, 14:21

I believe QF were the unlucky recipients of a one off event

I hope you're right Kremin.
Trouble with one off events - they have a nasty habit of repeating themselves.

cloudhawke

29th Jul 2008, 14:38

www.caa.govt.nz/Airworthiness_Directives/Components/emy.pdf

Page 7 may be of interest.

Swedish Steve

29th Jul 2008, 14:46

Thought it might be opportune to explain the oxygen system.
The B744 has a gaseous oxygen system. This was the norm back in the 60s, all aircraft were like this. The oxygen generators appeared in the early 70s, I first saw them on the L1011 where they were standard on the pax system. They are now standard on most aircraft. Unusually the B777 can be seen with both systems depending on the airline.
Anyway back to the B744.
The crew and pax systems are separate. The crew has one or two bottles, the pax side has a row of bottles, the total number depends on the airline fit. All the bottles are filled from one charging point. NRVs separate the crew and pax systems. The pax bottles are all connected to a common main through individual regulators. Loss of one bottle would not affect thesystem, unless the regulator was damaged when the whole system pressure could drain away.
The B744 pax system has two modes, therapeutic and emergency. Therapeutic is selected by a red guarded switch in the flight deck (looks the same as the manual on switch!) A none-surge flow control valve introduces oxygen at about 2psi into the pax supply. Separate masks can be plugged into this main.
If emergency is selected manually, or automatically via a cabin altitude switch, the surge flow control valves introduce oxygen at about 16psi into the same main. This higher pressure opens the PSU doors and allows the masks to drop. Each mask is individually actuated by pulling it down which releases a pin from the supply valve and oxygen starts to flow. The ring main pressure drops to 2 psi after actuation. Oxygen will continue to flow from each actuated mask until the system is switched off.

So, masks are dropped by oxygen pressure (the door latches are not electric)
The whole system is one big ring main.
All the pax bottles feed the same main.
Pulling the mask to your face should be sufficient to pull out the pin, but there is a streamer there that says pull on it.

Oxy generator systems are different in that the doors are opened electrically. Pulling on one mask starts the flow of oxygen to all masks in the same box.
The system cannot be stopped once started.
(Also once it is used it takes forever to replace all the generators).

1DC

29th Jul 2008, 15:21

If the rupture in the hull was caused due to some other reason rather than the failure of the oxygen bottle could the turbulence in the breached hull space be sufficient to cause an O2 bottle to become loose and fracture?

bvcu

29th Jul 2008, 15:37

If i remember correctly PAX oxygen is an option on 747 , i.e some have the gaseous system but most have oxygen generators. same with some other types i.e A340-300 at least one operator has gaseous.

Chris Scott

29th Jul 2008, 15:38

Thanks for your clear and succinct overview, Swedish Steve.

I wonder how many aviation people are as surprised as I am to learn that a B747-400 still uses an oxygen ring-main for the whole cabin; a feature I associate with the likes of the B707 and VC10.

One wonders what would have happened if the nearby flight-crew oxygen system had been taken out as a result of the explosion. It also highlights, however, the less than ideal concept of flight crews themselves having to rely on remote bottled oxygen systems, which I believe are still the norm on new types that use oxygen generators for their cabin systems. Fortunately, most types of flight-crew mask can be transferred to a portable (therapeutic) oxygen bottle, no doubt with limited performance. I dare say that crews on many aircraft types are rehearsing the procedure as I write.

As an ex-pilot, my recollection is that recharging (or exchanging) the bottles has always been a potentially hazardous operation. Are safer systems yet available?

MilktrayUK

29th Jul 2008, 15:50

Interesting Media Release. No mention of exploded aircraft oxygen cylinders or shrapnel in the aircraft cabin, only that they are examining the oxygen systems and they have retained some components and "parts of components".

Maybe there is a lot more to this chain of events than has been revealed so far. Am I the only one confused about the talk of a crew oxygen MEL, when the assumed missing bottle is from the pax supply? It seems too early to jump to the obvious conclusions.

Swedish Steve

29th Jul 2008, 16:18

I wonder how many aviation people are as surprised as I am to learn that a B747-400 still uses an oxygen ring-main for the whole cabin

I think the reason is extended operations over the Himalayas. A lot of B777 have oxygen generators, but the BA aircraft have oxygen bottles for the same reason. Oxygen generators have a limited life. I believe the best is about 30mins. This means you have 30mins to get down to 10000ft, and can impose flight planning restrictions over a large mass of high ground.
I know that when our B767 (with generators) fly certain routes they have to carry loads of portable bottles for this reason.

lomapaseo

29th Jul 2008, 16:33

Pilots' reaction to explosion missing from tape | theage.com.au (http://www.theage.com.au/national/pilots-reaction-to-explosion-missing-from-tape-20080729-3mv6.html)

my exerpts from article are;

..........."Unfortunately, the standard two-hour recording, which works on an endless loop principle, did not contain the de-pressurisation event," senior ATSB investigator Neville Blyth told a media conference in Manila.

"The oldest part of the recording on the cockpit voice recorder commenced after the descent and diversion to Manila, so the event itself appears to have been overwritten."

He said the audio could yet be "very, very useful" - including in relation to examining airflow. "There is a surprisingly large amount of information that can be obtained from acoustic spectrum analysis, if indeed we have a recording of the event," Mr Blyth said.

In some of the previous explosive decompressions the analysis of the CVR could distinguish between a bomb (overpressure followed by outflow) and a pure fuselage rupture (outflow). Additional factors include reverberation (reflected waves off bulkheads) and structure borne dialation waves. Too bad in this case that the info is overwritten. I was surprised about the time frame that the CVR was running after the event.

Mr Blyth acknowledged that the "most likely explanation for the absence of the cylinder" was that it was blown through the fuselage.

I am never sure about news articles and whether they are paraphrasing what is said or whether they are actual quotes. But the quoted article above seems to leave open the possibility that the Oxygen tank might not have ruptured and simply tore loose out the hole afterwards.

http://fromtheflightdeck.com/MEL/N_OXYGEN-200x0.jpg

74tweaker

29th Jul 2008, 17:15

My comments about the valve and pieces of the cyilinder were quoted from a CNN video of a interview with the lead investigator. I can't find the video - but here is the story: Valve in oxygen cylinder the culprit in 747 explosion - News - Travel (http://www.theage.com.au/articles/2008/07/29/1217097193736.html)

""We recovered a valve from an oxygen cylinder," Neville Blyth, a senior investigator with the Australian Transport and Safety Bureau, told a news conference yesterday. "It is likely that that valve is from the missing cylinder."

"The recovered valve is to be subjected to a forensic engineering examination at the ATSB's Canberra laboratory, where the cockpit voice recorder and flight data recorder are being downloaded. Maintenance records, including those for the oxygen supply system, are being scrutinised.

The valve had been found in the passenger cabin a couple of metres away from the bank of about six cylinders.

"The cabin floor of the aircraft has a hole approximately 20 centimetres in diameter above the location of the cylinders," Mr Blyth said. Asked if other 747s could have restrictions placed on them, Mr Blyth said a CASA representative was in Manila monitoring the investigation. This would allow for "any further safety action considered necessary", in addition to Qantas inspecting the oxygen systems on its 747 fleet, which is to happen by Friday."

infrequentflyer789

29th Jul 2008, 17:16

If they didn't pull them down firmly, no oxygen.
If they didn't see the transparent 'balloon' bit inflating, perceived lack of oxygen !

Some reports quote passengers who pulled the masks a bit too firmly and pulled them out of the ceiling. There are also reports of some masks not dropping and flight attendants having to pull them down. My guess is that masks failing to drop might be related to no oxygen pressure - or low pressure further away from the supply - are they all on one line/ring ?

The Beer Hunter

29th Jul 2008, 17:34

The pax bottles are all connected to a common main through individual regulators....The whole system is one big ring main.

masks-are they all on one line/ring ?

:ugh: I'm beginning to understand why the moderators cull these popular threads so hard.

Little_Red_Hat

29th Jul 2008, 17:56

With regards to pax oxy... getting a little bit off topic here, but oh well.

It was mentioned earlier that there's a need for explanation as to how much to pull on the oxygen mask/lanyard/tubing (whatever you want to call it).

I recall during my intial training years ago, my particular airline was quite specific about it being one (and ONLY one) firm pull... it was described to me as being 'about the same as one of those pull-chain lightbulbs'. Of course, not many people probably remember those now!! :}

Unfortunately, a lot of cabin crew out there dont know (or care) WHY the oxygen demo is (mostly) taught this way- not two yanks on the mask, ONE firm pull. So they continue to either 'pull-pull-yank' or just hold the tubing up and place the mask over their face, which further confuses the issue.

Perhaps a little reminder on the oxygen system is needed for the FAs of today?? Just a thought...

787FOCAL

29th Jul 2008, 19:02

The air pressure is not what makes them fall.

Swedish Steve

29th Jul 2008, 19:28

Infrequent flyer
My guess is that masks failing to drop might be related to no oxygen pressure - or low pressure further away from the supply

Swedish Steve
introduce oxygen at about 16psi into the same main. This higher pressure opens the PSU doors and allows the masks to drop.

I will try and explain more slowly. Oxygen pressure opens the latches and the panels in the PSU fall open. The masks are now sitting on nothing and will fall when gravity lets them.
The masks and the coiled up plastic tube are a snug fit in the boxes. Occasionally they will not drop by themselves and need a nudge. It really depends on how well they are packed. I personally find it quite difficult to roll up 4 masks and stow them in a box in situ, but it beats taking the boxes out on a transit!

ChristiaanJ

29th Jul 2008, 19:55

A thought....

The oxygen system is there in case of an emergency.... right?

Bird strike up front going through the window or the front bulkhead.
A window blowing out through a fault or a pax going crazy.
A fault in a door, like a cargo door blowing out.
A structural failure (with the 737 cabriolet as an extreme).

So the oxygen system is there as a backup/emergency system for such rather rare occurrences.

In other words, we thought we had two low-probability events: a rapid decompression AND an oxygen system failure, before we had a real problem

But maybe nobody did the sums for the case where the oxygen system itself was going to be at the origin of the decompression..... ?

Smilin_Ed

29th Jul 2008, 20:12

For those of us who are professional pilots but not airline pilots, what do the terms SLF and MEL mean?

DozyWannabe

29th Jul 2008, 20:27

Hope this isn't a wind-up

SLF - Self Loading Freight, i.e. you and I.
MEL - Minimum Equipment List, a list of items that the aircraft can still be dispatched with if not functioning.

ChristiaanJ

29th Jul 2008, 20:31

Posts: 36
Terminology
For those of us who are professional pilots but not airline pilots, what do the terms SLF and MEL mean?Ed,
In view of your number of posts, I can only just about believe you're not taking the mickey....

SLF: Self Loading Freight. The part of the payload you do not have to tie down on pallets, although, if you're cabin crew, you occasionally wish you could.

MEL: Minimum Equipment List. There are bits on the aircraft that are duplicated, triplicated and even quadruplicated. You ARE allowed to operate with some, but not all, of them inoperative. The MEL sets out in considerable detail what kind of defects you are allowed to carry, and under what conditions.

beamender99

29th Jul 2008, 20:39

A piece of an exploding oxygen tank is believed to have pushed the handle of an emergency door into the opening position, after smashing through the floor on a Qantas flight from Hong Kong.
Last Friday a Qantas international jet was forced to make an emergency landing at Manila after a mid-air explosion tore a hole in the plane's fuselage.
Passengers were not in danger of the doors opening because they are designed so they cannot be opened mid-flight, The Australian reports today.
But after examining photographs, industry observers were surprised the door was pushed into the opening position.
"It's an incredibly rare event for the oxygen tank to explode and for it to hit the door handle and rotate it open is just eye-watering," a source told The Australian.
The aircraft's controls were not affected but some computer functions and electrics were disrupted, including three of the plane's supposedly independent landing systems.
Sources said the emergency descent from 29,000 feet to 10,000 feet took about four minutes.

beamender99

29th Jul 2008, 20:59

Yesterday Qantas and the ATSB refused to comment on an engineer's claim that 346 passengers on the jumbo forced to make the emergency landing in Manila were starved of oxygen for several minutes after supplies were lost.
And an ATSB investigator said the jet's black box voice recorder did not capture the explosion that tore a hole in its fuselage.
The engineer, who can't be identified, said the three intact passenger oxygen cylinders emptied into the atmosphere after a regulator blew off the top of a fourth tank.
Passengers said several children wearing gas masks turned blue in the 10 minutes it took the aircraft to descend from 29,000ft to a safe breathing level of 14,000ft.
An aircraft engineer said there must have been some oxygen available because the doors that release the masks are oxygen-operated.
Sources said the steel regulator penetrated the cabin floor of the 747/400 after blowing off the cylinder in the cargo hold.

and the final info
The tank then flew around the hold like a rocket until it smashed through the outer skin.

Smilin_Ed

29th Jul 2008, 21:47

ChristianJ, I'm a U.S. Navy pilot. We don't use that terminology. :)

BTW, what does "taking the mickey" mean?

Pugilistic Animus

29th Jul 2008, 22:02

Retiring in 110 days - Probably one of my last posts.
:D
Happy contrails -

BelargUSA--I sincerely hope you continue to share your insights and wisdom with us---I hope this is not truly your last post:(

PA

Blacksheep

29th Jul 2008, 22:08

I believe QF were the unlucky recipients of a one off event, Exactly! A baffling unique event.

Try as I might, I haven't been able to find a single other instance of an aircraft oxygen cylinder bursting in flight, other then as combat damage in military aircraft, despite them having been in continuous service on civil airliners since the dawn of pressurised flight. Has anyone else has had more luck in searching for one?

ExSp33db1rd

29th Jul 2008, 22:16

Smilin Ed. Two Nations seperated by a common language !
Maybe you would understand Taking the P*ss ? :ok:

ChristiaanJ

29th Jul 2008, 22:24

BTW, what does "taking the mickey" mean?In the context of this forum, it would be asking a daft question that everybody would already know the answer to, aka "wind-up" or "send-up".

ChristianJ, I'm a U.S. Navy pilot. We don't use that terminology.OK, fair enough :)

SLF (self-loading-freight) is a somewhat deprecatory term that most people on this forum recognise.... It's the part of your payload that will get on board all by itself, without needing palletting or fork trucks. Aka passengers.....

The MEL (minimum equipment list) is a document that lists in considerable detail what defective items you can carry and for how long.
I'm sure the U.S. Navy has something very similar, but you may be calling it by a different name.

Also, from a very long time back, I know there is a vast difference between what you would accept for a peacetime training mission (when you were expected to bring the aircraft back in a state where it could be used again...) and the day when the balloon went up.

CJ

flynerd

29th Jul 2008, 22:31

Consensus appears to be that the bottle in question is one of the newer composite bottles. This has an inner aluminum liner. The regulator would be expected to be brass.

During the 6 months the bottle had been in place I would expect it to have undergone many cycles through a wide temperature range.

The two materials at the threaded top of the bottle would be Aluminum and Brass. These have quite different coefficients of linear expansion (COE). Those being about 24 * 10^-6 per centigrade degree for aluminum, and 19 for Brass.

Cold Aluminum is very brittle and could become cracked over time in the circumstances.
The disparate COE of these metals at this critical joint may be a big factor.

I suspect that this experiment with lighter O2 bottles may be at an end very soon!

Capt Kremin

29th Jul 2008, 22:39

The MEL was for the indicating system of the crew oxy. The indication was intermittent though working on the day. Its not relevant to this incident. The brackets holding the pax oxy bottles are not relevant to this incident. Parts of the bottle did indeed strike the door handle and rotate it more than 90 degrees. Think of the force needed to do that.

Joetom

29th Jul 2008, 23:04

Flynerd, think you hit it on the head.

These new weight/space saving devices are great in the purfect world, and that is the problem, we not in the purfect world.

Excuse the slip, but the 717 was developed because we don't live in the purfect world, fuel prices went up and the 717 was put out to grass.

Lets hope jet fuel slips back to $10 and the 717 has a fair run.

The cost of having these lightweight items fitted/re-fitted to aircraft looks like it may out weight the fuel savings in the future.

Keep yours eyes open for the next AD...it can't be far away.......

Litebulbs

29th Jul 2008, 23:07

Lucky the door didn't open, with equalised pressure not forcing the door closed. The opening mechanism must have been damaged whilst the cabin was still pressurised, because at the angle the door handle is in, it would be cracked open if normally moved.

flynerd

29th Jul 2008, 23:35

Thanks for the explanation re door opening/not opening. I would like to think that airspeed would also be a factor in not allowing the door to open, pressure differential aside. :ooh:

Litebulbs

29th Jul 2008, 23:39

Does it not crack in first, being a plug door?

Litebulbs

29th Jul 2008, 23:41

I would be reasonably sure that opening a door whilst in unpressurised flight was not one of the items that was tested during flight testing as could also be said for an oxygen bottle failure of some sort.

Machaca

29th Jul 2008, 23:48

flynerd

Composite cylinders have been in aviation use for decades -- hardly an experiment. I wouldn't be surprised if this aircraft was delivered with them.

Besides oxygen supply, composite cylinders are used for hydraulic accumulators, fire bottles, evacuation slides and more.

If you have knowledge of any newly uncovered issues re COE/CTE between aluminium and brass please do share it with us.

Machaca

30th Jul 2008, 00:09

A previous cylinder failure and hull breach (http://www.aaib.dft.gov.uk/cms_resources/BAe%20146-300,%20G-JEBB%2006-06.pdf) in a BAe-146:During the approach a loud bang was heard by the
aircrew, followed by a loss of the yellow hydraulic
system. After the aircraft landed safely a hydraulic
accumulator was found to have burst. The failure
was subsequently attributed to a material defect in the
cylinder wall of the accumulator.
The accumulator was . . . installed in the aircraft
10 months prior to the incident...

Probably several similar events over the years that we haven't heard about.

Brakes on

30th Jul 2008, 00:19

Guaranteed no speculation in this post, just a question.
There's something I don't understand about the VCR. It says this runs for two hours and then starts from the beginning and overwrites what's on it.
Quote from post 624:
Last night the aircraft cockpit voice recorder (CVR), which records crew conversations, radio traffic and cockpit ambient sounds, was downloaded by ATSB specialists in Canberra. Unfortunately, the standard two hour recording which works on an endless loop principle did not contain the event. The oldest recording commences after the descent and diversion into Manila, so the event itself appears to have been overwritten.
Unqote
... the event seems to have been overwritten... By what? From the event (1 hour into the flight) to the end of the VCR is about 1 hour, from start of overwrite to the event is another hour so it should have been recorded.
The information I've used here (times of events, technical info etc.) is based on posts in this forum, so some of it may have to be taken with a grain of salt, but at least the press release quoted in post 624 sounded to be from an official source.

rickshaw1

30th Jul 2008, 00:31

Smilin Ed:

ANFE (Aircraft Not Fully Equipped) might be the term you use instead of MEL.

c3pd

30th Jul 2008, 00:32

Quick question (from a passenger flyer only):

Is it not a possibly lucky event that whatever flew off the Oxy Bottle (Presumably the brass regulator?) actually hit the door handle and was therefore able to dissipate some of its energy into a moveable object...rather than hit the roof and possibly hole the aircraft from the inside? That door handle may have saved a bigger event?

Any feedback?

pasoundman

30th Jul 2008, 00:34

flynerd wrote:
Consensus appears to be that the bottle in question is one of the newer composite bottles. This has an inner aluminum liner. The regulator would be expected to be brass.

During the 6 months the bottle had been in place I would expect it to have undergone many cycles through a wide temperature range.

The two materials at the threaded top of the bottle would be Aluminum and Brass. These have quite different coefficients of linear expansion (COE). Those being about 24 * 10^-6 per centigrade degree for aluminum, and 19 for Brass.

Cold Aluminum is very brittle and could become cracked over time in the circumstances.
The disparate COE of these metals at this critical joint may be a big factor.

I suspect that this experiment with lighter O2 bottles may be at an end very soon!

Now THAT is a very interesting analysis.

pasoundman

30th Jul 2008, 00:42

In the old days of magnetic tape it's entirely understable how and why it was necessary to overwrite older recordings.

In these days of modern non-volatile semiconductor memory, could we not do a little better ?

Litebulbs

30th Jul 2008, 00:44

I was under the impression that a CVR recored the last 30 minutes of voice.

A. The voice recorder system preserves a continuing record of the latest 30 minutes of flight crew communications and conversations. The voice recorder receives inputs from the audio selector panels for the captain, the first officer, and the first observer, and from an area microphone in the flight compartment.

Pulled from a Boeing (not B747-400) MM

HotDog

30th Jul 2008, 00:50

Quote from New Zealand Airworthiness Schedule DCA/EMY/27A,24 May 2008
Oxygen Reserve Cylinders-Inspection & Replacement

To prevent oxygen cylinders exploding due to aging and deterioration of the
Aluminium Alloy 5283 (AA5283) cylinder shell material, identify the year of
manufacture of each affected P/N oxygen reserve cylinder made from AA5283 and
replace per the instructions in Eurocopter AS 350 Alert Service Bulletin No. 05.00.54.
Immediately after removing the oxygen cylinder from the aircraft, empty the cylinder
per the instructions in Intertechnique Service Bulletin (SB) GLD/GLF-35-150 dated 20
September 2006.
Note 3: Oxygen cylinders with P/Ns listed in this AD may only be used if the service life is
within the limitations of the compliance of this AD.
Note 4: Oxygen cylinders with P/Ns listed in this AD and which are held as spares are to be
inspected per the requirements of this AD. Identify the year of manufacture of the
cylinder and empty all oxygen reserve cylinders that have reached or exceeded 25
years after manufacture, per the instructions in Intertechnique SB GLD/GLF-35-150.
(EASA AD 2006-0286R1 refers)
Compliance: Within the next 15 days if the TIS cannot positively be established.
When operated in salt-laden atmospheric conditions:
At 15 years since manufacture, or within 15 days whichever occurs later.
When operated in normal climatic conditions:
At 25 years since manufacture, or within 12 months whichever occurs later.

NSEU

30th Jul 2008, 01:00

Cold Aluminum is very brittle and could become cracked over time in the circumstances.

Are we talking about pure aluminium or aluminium alloy? Remember that the entire fuselage is made of aluminium alloy ;)

Capt Kremin

30th Jul 2008, 01:03

The CVR was probably still running after the aircraft came to a halt on the runway. It took some time for it to reach the gate apparently as it was towed in. I don't know how long after that it was powered down. It probably explains why the incident itself was overwritten.

flynerd

30th Jul 2008, 01:12

If you have knowledge of any newly uncovered issues re COE/CTE between aluminium and brass please do share it with us.

No _new_ issues, only those that have existed for all time.
In the Navy, you learn to never tolerate iron/aluminum direct contact joints because of electrolysis.

I do not know what Al alloy is specifically used in these composite bottles, but the boundary interactions between the metals used in the bottle and the regulator would appear to be a real target for the investigators in this case. This despite the fact that they may have been standard practice for some time. This was not an exploding bottle ( my guess). This was a bottle whose regulator popped out in a real hurry. I am not addressing the walls of the bottle, but the brass/aluminum interface. If the bottle could ever be found at the bottom of the sea, I suspect it would be mostly intact with some superficial external damage.

loaded dog

30th Jul 2008, 01:16

Is it not a possibly lucky event that whatever flew off the Oxy Bottle (Presumably the brass regulator?) actually hit the door handle and was therefore able to dissipate some of its energy into a moveable object...rather than hit the roof and possibly hole the aircraft from the inside? That door handle may have saved a bigger event?Interesting thought.
Many people have also probably wondered about what would have happened if the liberated O2 found an ignition source but have tastefully kept their thoughts to themselves. At the risk of starting a bleak discussion, my understanding is that cargo fire systems are based on fire suppression only.

Litebulbs

30th Jul 2008, 01:17

It doesn't take a lot to thread a brass fitting, especially if you use a Boeing spanner!

pacplyer

30th Jul 2008, 01:22

Thanks for those great photo blow ups you guys. I continually marvel at your photo high-res skills. Composites are good stuff if they are not damaged. Carbon fiber by itself won't work good for tension loads, hence Kevlar is added to the pressure vessel of little aircraft like the pressurized lancair IV.

(To the best of my memory. Feel free to correct me.)

Click on this link to see what composite aviation oxygen bottles look like:

SCI (http://www.scicomposites.com/aviation_cylinders.html)

Note the ridges on the side of the bottles from this vender.

Breathable aviation O2 tanks are supposed to be green, I know. For some reason, in the 80's, our composite bottles were white and racked horizontal inboard of the frames in a cluster, not stored against the aircraft skin like you see in the previous space saving photos. But putting them in the side wall of the cargo compartment probably gives this -400 more lower cargo positions; I don't know.

But we are talking about millions and millions of flight hours over decades without a single known cylinder explosion. Kind of looks like a little charing on that last photo blow up. But no way to know which came first.....

Let's revisit the known Leak problem for a minute:
I think it's important to recall that the "shards" so far that we have been hearing about are not talking about actual bottle material, right? Just attached hardware like regulators etc which could have been leaking and snaked their way to a [fuel & ignition] source. So it doesn't necessarily matter whether the leak came from the crew or pax systems in that scenario, it only matters that the oxygen collected in the compartment down near the hull, got in contact with a [fuel & ignition source like a venting battery in the E&E compartment] and blew out the lower 42 skin while also buckling the floor upwards.

The intact missing oxygen bottle (which got sucked through the wall) is now being used by a chinese brain surgeon who bought it at the fish market having spotted it in the netting. ;)

One thing's for sure: Just in case that's wrong, I'll have to start wearing my flack jacket when I stow away down there from now on..... :E

NSEU

30th Jul 2008, 01:26

There's something I don't understand about the CVR. It says this runs for two hours and then starts from the beginning and overwrites what's on it.

According to the report, it sounds like the QF30 had the newer type digital recorder with 120 minutes of recording (although some of the 744's may still have the older 30~40 minute tape type).

The erasure process doesn't wipe out the entire 2 hours. The tape or memory will always have the last 2 hours of the flight on it (or 30 minutes). CVR's on Qantas' 744's are operational whenever there is power on the #3 AC Bus. If the CVR circuit breaker was not pulled and power remained on the aircraft after landing, then the CVR would have continued running ... and the explosive event would have been overwritten.

Barkly1992

30th Jul 2008, 01:29

Loaded dog

Another hole (small) would have been redundant - the one in the hull was all that was required.

O2 does not burn.

Gees

flynerd

30th Jul 2008, 01:47

Are we talking about pure aluminium or aluminium alloy? Remember that the entire fuselage is made of aluminium alloy

Yes mate, but the wall/frame of the AC might heat and cool a lot, and the only thing retarding its movement is the air around it.

The thermal conductivity of Al is about 120k (Btu per fDegree per square foot). For brass this figure is about 67k.

Thus the Al will cool quicker, and will shrink faster ( Al COE=24 as against Brass COE=19 ) around the regulator. Looking at the interface between the two there has to be considerable action/reaction at the joint. Think about how a soft little toadstool can push up through a bitumen road surface.
Now if the Al alloy used is purposely designed to contain a gas, then it could be quite different from one that only needs to behave well with a brass regulator. And I would expect the bottle alloy composition would be far removed from that used in an AC skin.

Boy, would I ever love to get the adjacent bottle and test cycle it -50C to +50C under pressure for another 1000 cycles. Thant said, I would LOVE for it to hold up and disprove my theory.

Machaca

30th Jul 2008, 01:50

Carleton composite cylinder and valve assembly (http://www.carltech.com/pdfs/200-003-902-B42365-1.pdf) (part number B42365-1):

Specifications:

Operating Pressure...0 to 1850 psig @ 70 deg F (0 to 128 barg @ 21 deg C)
Burst Pressure.........6290 psig (434 barg)

Proof Pressure.........3085 psig (213 barg)

Media....................Gaseous Oxygen per MIL-PRF-27210

Materials
...Hand Valve..........Brass & stainless steel
............................Oxygen compatible silicone O rings

...Cylinder..............Aluminum alloy, 6061-T6 liner
...........................T700 Carbon Fiber overwrap

Internal Volume......115 cubic feet (3.26m3) Oxygen @ 1850 psig (128 barg), 70 deg F (21 deg C)

Weight.................19.6 lbs (8.9 kg) maximum empty
...........................29.5 lbs (13.4 kg) maximum full

Cylinder Certification... DOT-E 11194 & DOT-CFFC

Operating Environment:

Temperature......... -65 to 160 deg F (-54 to 71 deg C)

Shock.................. 6 g operational
20 g crash

Vibration ............. 9.5 Grms each axis

Product Interfaces:

Outlet/Fill Port.......CGA-540
..........................903-14NGO-RH ext thread

Safety Outlet Port..MS33649-05 (AS5202-05)

Barkly1992

30th Jul 2008, 02:05

Loaded Dog

What sort of ignition source - a barbeque or something? Your comment just does not make sense. If there was a fire onboard the oxygen would just help to keep it alight for a short while - no doubt go out once the cabin ventilated.

Silly speculation with no reason to raise such hypothesis.

flynerd

30th Jul 2008, 02:14

http://i37.tinypic.com/2wp7di9.jpg

Thanks for the bottle specs Machaca. Looks like they are not using brass-in-aluminum for that bottle.

Looks like we still need to wait on what the ATSB tell us about the bit they recovered from the galley.

loaded dog

30th Jul 2008, 02:40

Point taken grumpy. I had already deleted previous post.
Turns out to be another oxygen irony
Firstly: backup system places demands upon itself (as rumour has it)
Secondly: Redeems itself by creating hole in hull that reduces potentially dangerous enriched oxygen area.

pacplyer

30th Jul 2008, 02:49

Interesting thought.
Many people have also probably wondered about what would have happened if the liberated O2 found an ignition source but have tastefully kept their thoughts to themselves. At the risk of starting a bleak discussion, my understanding is that cargo fire systems are based on fire suppression only.

Point taken grumpy. I had already deleted previous post.
Turns out to be another oxygen irony
Firstly: backup system places demands upon itself (as rumour has it)
Secondly: Redeems itself by creating hole in hull that reduces potentially dangerous enriched oxygen area.

Exactly loadeddog, :D

I think we're all thinking the same thing after that last enlarged photo showing [possible] black charing:

[Hypothetically speaking only:]
The oxygen [and unknown fuel source like hydrogen from a battery] ignited from a spark (perhaps in the adjacent (e&e) electrical bay) caused an explosion yielding the sidewall, causing the decompression.

The decompression snuffed out the fire before it could it could get burning significantly. The debris we see hanging out was sucked into place after the tank, sidewall and fairing fell away in the slipstream; hence, it shows no evidence of scorching and fooled the chit out of us for days.....

Plausible?

pac "Sherlock" plyer

.

lomapaseo

30th Jul 2008, 03:17

I think we're all thinking the same thing after that last enlarged photo showing black charing:

The oxygen ignited from a spark (perhaps in the adjacent (e&e) electrical bay) caused an explosion yielding the sidewall, causing the decompression.

The decompression snuffed out the fire before it could it could get burning significantly. The debris we see hanging out was sucked into place after the tank, sidewall and fairing fell away in the slipstream; hence, it shows no evidence of scorching and fooled the chit out of us for days.....

Plausible?

pac "Sherlock" plyer

You can enter your horse in the race if you want, but you don't need to immagine that you see charing in a photo to speculate that partially confined oxygen between a blanket and a side wall could ignite for a second and cause a local overpressure. Just use the "could have" and the ripped out lower rivet line.

Maybe we can get "Myth Busters" to run this experiment

Buster Hyman

30th Jul 2008, 03:23

With trepidation & clutching my Degree in Aviation Engineering from Corn Flakes University...I stray from reporting on one punters experience to asking a technical question....

Would not a fire trigger the alarms in the cockpit, or are we talking a "flash" fire here?:confused:

pacplyer

30th Jul 2008, 03:25

Good point loma, Thanks

I've changed it to "hypothetically" and "possible black charing."

But that is the 747 freighter procedure for long range fire. Loose the cabin pressure by driving the outflow valves full open; which starves the fire of oxygen. In our leak/bang theoretical, it's a flash fire that gets extinguished almost immediately. Fire detection may not come into play as they are optical sensors that look for obscuration of the internal light source much like your fire detector at home. Dust raised during loading sometimes sets these things off but not sure about a flash fire? Usually smoke would have to be present for a number of seconds to make them decide it's for real. If the air volume gets evacuated in seconds?

(Cornflakes university is one of the better mail order degrees by the way; highly respected :})

Machaca

30th Jul 2008, 03:45

If the failure was at the cylinder neck/valve assembly, then the equal/opposite reaction may have caused the cylinder to pivot at the upper strap mount, forcing the bottom towards the hull and either rupturing or penetrating the hull.

http://i337.photobucket.com/albums/n385/motidog/QF30-Cyl4breach-1.jpg

llondel

30th Jul 2008, 04:04

There's actually quite a lot of stuff that will spontaneously combust in the presence of pure oxygen (hence the "do not grease" instruction for oxygen pipe and valve gear), so it's quite possible that a small leak and some contaminant on the pipe (maintenance guy with slightly greasy hands handling the pipe, perhaps) could generate that if a leak was blowing oxygen along the pipe from its valve connection. Low temperature would tend to inhibit things from starting, but if it started on the ground it could generate enough local heat to be self-sustaining as the environment cooled off.

I'm not sure how any of that would cause the bottle to rupture though, so it might be an after-effect rather than a cause. (OK, I can think of a way but the probability is only marginally greater than the golf-club-from-outer-space theory that appeared earlier in the thread)

Wunwing

30th Jul 2008, 04:41

Buster
As outlined by pacplyer,the fire detection system works on optical obscuration of sensors by combusted particles. The particles/cabin air is drawn through a chamber via cabin differential pressure. If there is no differential pressure such as in a decompression, there is no sampling and no fire alarm.

Wunwing

Annulus Filler

30th Jul 2008, 04:49

Typical part number of an oxygen bottle for this installation is 801307-00.

Aerolex

30th Jul 2008, 05:31

Some FACTS emerging...

4000fpm??? Hardly a 'plunge'!
O2 masks not deploying?? NOT!

http://www.atsb.gov.au/newsroom/2008/release/2008_28.aspx (http://www.atsb.gov.au/newsroom/2008/release/2008_28.aspx)

cambruzzo

30th Jul 2008, 05:59

MEDIA RELEASE

2008/28

Investigation into Boeing 747- 400 depressurisation and diversion to Manila, Philippines

30 July 2008

Introduction

As you are aware the ATSB is leading this safety investigation with the assistance of a number of other organisations and agencies, including the Civil Aviation Authority of the Philippines, the National Transportation Safety Board and the Federal Aviation Administration of the USA, the Civil Aviation Safety Authority of Australia, Qantas and Boeing.
Flight Data Recorder

The data from the flight data recorder has been recovered and downloaded. Initial analysis of the data indicates that the aircraft decent from the decompression event at 29,000 feet to the altitude of 10,000 feet, where no masks are required, took about five and half minutes, with an average descent rate of about 4,000 fpm. The ATSB is still verifying and analysing the data on the recorder.
Door

The ATSB can confirm that it appears that part of an oxygen cylinder and valve entered the passenger cabin and impacted the number 2 right door frame handle, thereby moving the handle part way towards the open position. However, the door handle mechanism has been sheared as it is designed to do if an attempt is made to open the door in flight, so the position of the door handle is not representative of the position of the door lock mechanism or the security of the door. The investigation team have confirmed that the door latches were still engaged. Additionally the door is of the plug-type that first needs to be pulled into the cabin, rotated 90 degrees then pushed out to open. So there was never any danger of the door opening.
Cabin Masks

The investigation team have surveyed the passenger cabin including the oxygen masks. The team found that most of the oxygen masks had deployed correctly from the passenger modules and had been pulled to activate the flow of oxygen to the mask. According to the airline, there were 346 passengers on board. Inspection by the ATSB shows that 484 masks had deployed, that is, dropped from the ceiling. Of those, 418 had been activated by pulling on the mask to activate the flow of oxygen. Only a small number of masks appeared to have had the elastic retaining strap adjusted by the passengers. It also appears that a small number of masks did not deploy from the passenger modules. Investigations into this aspect of the accident are continuing.
Interviews are continuing with the cabin crew in relation to this issue. Additionally, the ATSB is preparing a passenger survey that will be sent to all passengers to gather information about their experience of the event. The ATSB also plans to interview those passengers that encountered specific problems either with the masks or the decompression event.
Oxygen System

The investigation team is still examining the oxygen system, including liaising with the manufacturer to determine if the flow of oxygen was adequate for the five and a half minute descent to 10,000 feet, where the masks were no longer required.
ILS

The team have confirmed that the aircrafts three Instrument Landing Systems (ILS) and the anti-skid system were not available for the arrival and landing at Manila. However, evidence to date indicates that all the aircrafts main systems, including engines and hydraulics were functioning normally. The approach to Manila airport was conducted in visual conditions. It should be noted that other pilot navigation instruments (VOR and NDB) were still available to the crew should the conditions not have been visual. Additionally, Air Traffic Control could have provided radar assistance if the crew had required it.
Flight Crew

From the evidence gathered to date it appears that the flight crew have responded to and managed the emergency situation extremely well. It is apparent that they followed the procedures they have trained for in simulators, which ensured the best possible outcome for the aircraft, the passengers and crew.
Notify ATSB

A reminder that the ATSB requests that any passengers that experienced issues during the flight, or those who photographed or videoed the incident, contacts us via email [email protected] ([email protected]) , telephone: 1800 020 616, or facsimile 02 6247 3117.
The investigation will need time to review and analyse the evidence collected to date and to plan and undertake further evidence gathering and analysis. It is difficult to say how long an investigation such as this will take. However, a preliminary factual report will be released by the ATSB within about 30 days and, should the need for urgent safety action by any agency be identified, the ATSB will immediately notify the relevant agencies who are best placed to address the issue. At this point, unless there is any significant development in the investigation, further media conferences are not anticipated and further information will be released as part of the ATSBs preliminary report.

Media Contact: George Nadal during business hours & after hours duty officer: 1800 020 616

MEDIA RELEASE : 30 July 2008 - Investigation into Boeing 747- 400 depressurisation and diversion to Manila, Philippines (http://www.atsb.gov.au/newsroom/2008/release/2008_28.aspx)

limelight

30th Jul 2008, 05:59

Oxygen cylinder at fault in Qantas emergency: ATSB

full story at Oxygen cylinder at fault in Qantas emergency: ATSB - ABC News (Australian Broadcasting Corporation) (http://www.abc.net.au/news/stories/2008/07/30/2319138.htm?section=justin)

cambruzzo

30th Jul 2008, 06:07

Oxygen cylinder at fault in Qantas emergency: ATSB

Posted 41 minutes ago
Updated 21 minutes ago

Air safety investigators have confirmed an oxygen cylinder was to blame for an explosion on a Qantas 747 last week.
The jet was forced to make an emergency landing in Manila after a blast blew a hole in the fuselage.
The Australian Transport Safety Bureau's (ATSB) preliminary investigations have also found a small number of oxygen masks in the plane did not deploy.
"The team found that most of the oxygen masks had deployed correctly from the passenger modules and had been pulled to activate the flow of oxygen to the mask," the ATSB said in a statement.
"Only a small number of masks appeared to have had the elastic retaining strap adjusted by the passengers.
"It also appears that a small number of masks did not deploy from the passenger modules.
"Investigations into this aspect of the accident are continuing."
The bureau says it intends to interview Qantas cabin crew and passengers who encountered problems with their oxygen masks.
The ATSB also confirmed that the Qantas flight crew handled the situation well.
"From the evidence gathered to date it appears that the flight crew have responded to and managed the emergency situation extremely well," the statement said.
"It is apparent that they followed the procedures they have trained for in simulators, which ensured the best possible outcome for the aircraft, the

passengers and crew."
The ATSB is asking any passengers who managed to photograph or video the in flight drama to come forward.

NSEU

30th Jul 2008, 06:25

Just wondering what corrosion inhibiting compound would do in combination with, say, a tiny leak in the oxygen plumbing? I assume it's a hydrocarbon of some description.

I'm guessing it's not very reactive, however, once the compound dries.

Rgds.
NSEU

Aerolex

30th Jul 2008, 07:17

I've got some Boeshield T9 at home. I'll spray some, let it dry and then throw it on the fire. Very waxxy substance one dry, my guess is it will still go 'wooshkah' when it hits the heat.

MWK7676

30th Jul 2008, 07:54

Fresh off the press

The Australian Transport Safety Bureau (ATSB) said today a piece of the oxygen tank entered the passenger cabin after smashing through the cabin floor and hit an emergency door handle, moving it part way into the open position.

ATSB spokesman Julian Walsh said passengers were not in danger, because the position of the handle did not mean the security of the door was at risk.

Passengers not in danger? Good thing the door handle wasn't a Pax head

Pontius Navigator

30th Jul 2008, 08:04

Passengers not in danger? Good thing the door handle wasn't a Pax head

Don't tempt me, don't tempt me :}

NSEU

30th Jul 2008, 08:33

I've got some Boeshield T9 at home. I'll spray some, let it dry and then throw it on the fire. Very waxxy substance one dry, my guess is it will still go 'wooshkah' when it hits the heat.

No heat required.... oxygen and hydrocarbons provide their own heat ;)

Max Tow

30th Jul 2008, 08:44

Amazing how the press comments reported above mangle the well chosen words of the ATSB statement.

The ATSB has NOT said that the oxygen bottle was to blame for the decompression. All that is apparent is that one disintegrated, which leaves open that this was either a cause or consequence.

The ATSB has NOT said that passengers were not at risk from flying debris or the event per se, simply that there was no risk of the damaged door opening.

Ripline

30th Jul 2008, 09:00

Swedish Steve

30th Jul 2008, 09:04

I would have expected at least a lower cup support

There is. The cylinders are round at the bottom and sit in a cup shaped housing.

beamender99

30th Jul 2008, 09:08

The ATSB can confirm that it appears that part of an oxygen cylinder and valve entered the passenger cabin

So it was not just part of the valve that went up into the cabin.
It still seems very fortunate that the remaining parts of the cylinder left the hull and did not cause more damage.

No mention of any other parts of the cylinder found onboard
No mention of how much or what else got sucked out.

So was it just the top ?/neck of the cylinder that got detached and the almost intact remainder that exited?

Slats One

30th Jul 2008, 09:31

Shoot me down for arrogance why don't you, but on 25th July I posted the comments at base of this post.

(Original post: page 9 post number 166).

I had hoped others would debate the point I raised.But the point was ignored.

It would appear my onservations about damage thru the structure and particularly in the door frame were 100 per cent accurate - resultant not causative context of course.

Given the 36 pages of speculation the event has created, I now claim a golden b...ock award for smugness and accuracy of investigative observation. The media missed it too! Yippee. They had to wait for the ATSB to say it 6 days later...

I thank you.

EXTRACT POST 166:

"Of note is that in the internal galley/door 2 right shots, the internal trim on the forward edge of the door psot has been damaged. This may explain a possible initial cabin crew report of a door going or a main door warning light flashing on the flight deck.

Given that the interior door panel/post is showing damage, it is clear that the force of the so far unknown event did go thru the structure adn it is further evidence just how lucky QF are- and how stong Mr Boeing makes a 'plane."

Ends

Big mustache

30th Jul 2008, 09:39

cwatters

30th Jul 2008, 09:56

Attn Pacplyer,

Can I point out that pure Oxygen does not burn or explode so it makes no sense to talk about the oxygen leaking, finding a source of ignition and exploding. If you toss a lighted match in a room full of oxygen.. the match will burn faster and use up some of the oxygen but once the match is all burnt up the fire goes out. The Oxygen will NOT explode or burn.

Now if the bottle had been filled with hydrogen by mistake and that leaked then it would be a very different matter. No evidence for that though.

chris weston

30th Jul 2008, 10:06

Blacksheep 667

No I can't find reference to any such cylinder failure either, and I guess like you too, have looked assiduously.

I can't even find such a (spontaneous?) failure documented at ground level.

I have worked with, on and off so to speak, a variety of compressed gases (O2, N2, H2, CO2, C2H4, C2H2) over the years.

For the record, the vent hole on all the cylinders I have come across is set at an angle (not sure of exact angle, apparently it can vary). This makes sure that you don't get a 180 degree staight line torpedo in the event of a catastrophic valve assembly failure eg cylinder being dropped from height on a building site. What this means is you get a high speed circular path if the top gets ripped off. :(

Are the various gas cylinders in use on aircraft engineered in the same way I wonder? I can't find that either.

CW

Aerolex

30th Jul 2008, 10:08

No probs NSEU,

I understand the risks of hi pressure O2 and it's ability to ignite even alloys. Some years ago Continental forbid us to replenish systems whilst cylinders were onboard. They were a bit 'edgey' after they lost an ACFT (due to fire) during onboard replenishment.

Anyway, I just like to burn things so i'll still go ahead with my little T9 flammablity test!!!:eek::eek::eek:

Max Tow

30th Jul 2008, 10:13

Interesting photo from Machaca. Like Ripline, I find the restraint and lack of protection of these cylinders quite surprising. Machaca suggests a cylinder failure might have caused the cylinder to pivot to the angle shown. What if a prior failure of restraint or to properly restrain had allowed the cylinder to lie in the position shown, thereby exposing the valve mechanism (always the weak point of a compressed gas container) to be exposed to being whacked by a ULD on one or more occasions. It would be interesting to know the clearances. The comments by Mr Walsh on the ABC website suggest that this is one of many avenues being covered. As many have remarked on this forum, spontaneous explosion of the cylinder body would presumably have left far more debris and wider damage.

Oxygen cylinder at fault in Qantas emergency: ATSB - ABC News (Australian Broadcasting Corporation) (http://www.abc.net.au/news/stories/2008/07/30/2319138.htm)

pacplyer

30th Jul 2008, 10:39

cwatters:

Thanks for that. So by itself, an accumulated concentration of oxygen in a chamber doesn't have the potential to ignite with an explosive force; is that what you're saying? :confused: It must be combined with another element (like hydrogen from a venting battery) to explode?

Though I have never witnessed it, I have read reports in Aviation Safety and Aviation accident classes of personnel burning to death from oxygen soaked clothing. But that is a simple burning process, not an expansion by itself I guess. The crew of apollo one/seven Grissom, White and Caffie experienced an intense rapid fire in the presence of 100% oxygen on the launchpad most likely ignited by a spark from electrical equipment. Nobody could get near it, but I don't recall an explosion except secondary bottles going off If I remember correctly.

But I think what you say is true now that I think about it.

Oxygen by itself is not an explosion hazard; so the leak/bang theory is not plausible without another catalyst of some sort.

Good group on this board... and thanks cwatters for straightening me out on that.

[added: So pure oxygen leaking is a hazardous oxidizer looking for a fuel source. Would you buy that?]

[I have modified my previous posts to include that omission of this theory]

HotDog

30th Jul 2008, 11:38

Max Tow, thereby exposing the valve mechanism (always the weak point of a compressed gas container) to be exposed to being whacked by a ULD on one or more occasions.

It would be extremely difficult to whack any part of the Oxygen system by a ULD as none of it protrudes outside the vertical ribs and covered by panels in the cargo compartment. Have you ever observed the loading of ULDs in the cargo hold? PDUs (Power Drive Units) propel the ULDs along retractable guide rails into the required load position. The ULDs are shape designed to suit the shape of the cargo hold sidewalls and there is no danger of penetration of panels or curtains and interference with oxygen, cargo fire bottles, cabin pressure relief valves or potable water tanks, which they cover.

mickjoebill

30th Jul 2008, 11:44

Is it pure Oxygen? if so why is this used and not air?

Mickjoebill

NSEU

30th Jul 2008, 11:50

Apologies if this has already been mentioned, but would it not be a good idea if the cabin crew mentioned the likelihood of a rapid descent in the event of the oxygen masks being deployed during the safety demonstration, thus depriving the media of the "plummeting towards the ground" stories?

Qantas has additional safety information in their inflight literature, but I doubt many bother to read it. An example, is keeping on your shoes for takeoff and landing... but even the seasoned travellers in business class ignore this.

Some people seem to think that flying around in a metal cylinder at 800kph is perfectly safe :}

ZFT

30th Jul 2008, 11:59

Some people seem to think that flying around in a metal cylinder at 800kph is perfectly safe

In comparision to any other form of mechanical transportation, it is. If your average pax for one second thought it to be unsafe, there wouldn't be an airline industry.

infrequentflyer789

30th Jul 2008, 12:00

Some FACTS emerging...

4000fpm??? Hardly a 'plunge'!
O2 masks not deploying?? NOT!

On masks not deploying - quoting the ATSB:

a small number of masks did not deploy from the passenger modules

That "most" of the masks deployed (which we know from videos) isn't going to be much comfort if it's your row that doesn't deploy.

Also, 346 passengers, but 418 masks activated - something clearly wasn't right.

[ Well, we know something wasn't right since one cyclinder had decided to exit through the hull, so clearly the system was compromised. Questions will be around did it perform as expected/designed in the event of a cylinder going awol. ]

NSEU

30th Jul 2008, 12:02

Is it pure Oxygen? if so why is this used and not air?

I've been told it's pure oxygen.
I assume to get the same amount of oxygen into the passengers' lungs using compressed air, the bottles would have to be 5 times as big.... so there'd be a big weight/space penalty. The air we breath at sea level is 20% oxygen.

And wouldn't any gas under the same pressure be just as "propellant"?

R04stb33f

30th Jul 2008, 12:13

Is it pure Oxygen? if so why is this used and not air?

The number of oxygen molecules in a given space is greater at sea level than at altitude.
A person breathing normal air at sea level has no problems
A person breathing normal air at 30,000 feet can't get enough oxygen into his/her lungs because the air is far less dense.

Applying pure oxygen would increase the percentage of oxygen molecules per ambient air molecules at the lower density, thus maintaining breathable levels.

Incidentally, if compressed air was used, as soon as it left the regulator it would have the same density as the ambient air and would make no difference.

RB

Litebulbs

30th Jul 2008, 12:16

HotDog,

What if the baggage that you can see in the many pictures of the hole, was pallet loaded? I have seen plenty of cargo hold lining damage (a check prior to ETOPS departures) made by ULD's whilst loading. The cargo liner is not particularly thick and the O2 bottles are covered by a fabric curtain.

infrequentflyer789

30th Jul 2008, 12:23

And look out of the window in case the wing is engulfed in fire.

If you mean after an emergency landing / crash, then that is already in the saftey cards (at least the ones I can remember). If you mean in-flight, then I would advise caution - if you keep leaning over to the windows to check the wings, sooner or later someone is going to ask why, and explaining that you are "checking if it is on fire" might well get misunderstood these days.

On the shoes and trousers bit, a friend of mine, if he had had his own way, would have banned anyone not properly dressed for survival.

Might not be a bad idea, there have been a number of crashes where people have survived the impact (with survivable injuries) and died of exposure. On the other hand if you were properly dressed and equiped for survival, you won't get get through security in the first place. Maybe the lifejackets should all have a survival kit attached - say foil blanket, firelighters, flares, knife, etc. :\

RomeoTangoFoxtrotMike

30th Jul 2008, 12:26

SLF Alert....

With reference to Machaca's picture on post #703, I'm amazed that there only appears to be one retaining strap near the tank neck. Given the potential for stored energy to move the cylinder mass around this pivot point (as he illustrates) is this the only mechanism used to stop it going walkies? I would have expected at least a lower cup support or a rear vertical spine plus a lower strap system.

Not exactly relevant I know but I wouldn't dream of flying a hot air balloon without two strapping systems on the flight cylinders - and my landings are (usually) not much more violent than a 747's arrival.

I only ask 'cos I'm interested.

Ripline
G, I imagine that Mr Boeing has assumed that the friction of the strap is sufficient to stop the cylinder from bouncing out of it's "cup" (reference "Swedish Steve"), even in the event of a "firm" landing. Further, I imagine that they assume that any failure of the valve/regulator assembly would result in vertical forces pushing the cylinder down into it's mounting cup... :suspect:

I've no idea about the validity of the latter, but you and I were both taught by the short round chap of the risks associated with the former assumption... :eek:

HotDog

30th Jul 2008, 12:49

Litebulbs, if they load a pallet which is assembled to strict qualifications regarding content and shape, it is still guided into it's designated position by the mechanised loading system; same as the ULDs. Further more, a pallet is a flat piece of metal of approximately 2cm thickness. The neck of an oxygen bottle is about 2/3 up the sidewall of the cargo compartment. If you are familiar with loading cargo, you would also know that once in the desired position as per load sheet, ULDs, pallets, are secured by pallet locks which prevents any shift of cargo until unlocked. I have many hours in my logbook, flying freight; main deck and lower. I do wish however, that a professional loadmaster would voice an opinion on this subject, bless their souls; not many of them left these days in aviation.:sad:

Max Tow

30th Jul 2008, 12:55

Hotdog
As you say, nothing should protrude if everything is where it ought to be - my query was whether the gap between curtain & ULD/pallet was small enough such that a loose cylinder still on its stand but leaning into the curtain would bulge outwards enough to be hit at its extremity (i.e. the valve) during loading. Like Litebulb, I've seen plenty of cargo being loaded and plenty of sidewall damage but am unfamiliar with how generous are the 747 lower deck clearances. I guess the point is that (as the ATSB seem to imply) it's thankfully almost unheard of for a cylinder to just explode without a degree of provocation, & that the valve area is the inherent weakspot.

PS Infrequent Flyer 789: "Also, 346 passengers, but 418 masks activated - something clearly wasn't right." You expect a serious answer to that? Must have been a failure of the bumonseatsensor....

Aerolex

30th Jul 2008, 13:02

Infrequentflyer789,

I don't understand your argument...

The point I was attempting to make is that 'the media are a bunch of wnkrs. :)

There was no 'plunge' or 'plummet' nor was there a critical issue with O2 masks.

FYI when testing O2 systems on RPT ACFT (in Australia anyway) there is a certain number of masks that are permitted not to deploy. The key thing here is that the masks that don't deploy should not be adjacent to each other.

Being an 'infrequent flyer' you might not be aware that there are extra masks in every PSU (pax service unit: above your head). For example, the 3 seats outboard of a 747, there will be 4 masks drop from the PSU in a depresurisation event. Plenty of masks for all even if yours dont drop.

The location of where the masks failed to deploy will be the issue, not the number, trust me. :ok:

As far as numbers go, 418 out of 484 masks for 346 PAX sounds pretty good to me. :)

pacplyer

30th Jul 2008, 13:14

LoL Hotdog,

The real world is different imho. I've had flights where the 2cm steel pallets were stacked to the ceiling and burned out the smart wheels on a freighter because they were so heavy (they were pushed by a forklift on the ground the top ones rotated sticking them into the thin fiberglass liner of the compartment. I've had cargo build ups fall over in turbulence.

I had one flight (A310) where almost all the floor/pallet locks were forgotten in the lower hold, and it sounded like a subway/then a crash even way up in the cockpit everytime we changed deck angle/power. Sent the F/O down to investigate. It ruined his white shirt! (but he got all the locks up.)

Yes, the real world is something different all together. I still agree with you that it seems unlikely that a puncture could damage something in that location, but who knows what's been going on down there unsupervised during loading?

Stuff happens.

SLF hear strange bangs in the night! Contract people scamper off with their tail between their legs and don't tell anybody because they don't want to get canned.

Those reality things said, I should point out that I feel Qantas is a great airline staffed by exceptional pros. If I had to put my family on an airline, it wouldn't be Kor or Dynasty, that's for sure; it'd be Qantas!

HotDog

30th Jul 2008, 13:38

Max TOW, review post #519 on page 26 and post # 621 on page 32.

pacplyer, I don't doubt you at all. However it would help if you had added operator location. Africa maybe? I am pretty certain this situation would not be allowed to occur on a Qantas aeroplane and it certainly did not have anything to do with with the depressurisation incident. The missing bottle was not in the vertical stack on the starboard side of the LFW cargo hold but a horizontally mounted bottle at approximately STA880, aft and above the loading zone.

Litebulbs

30th Jul 2008, 13:50

Hotdog,

I know what a pallet is and I know its location with regard to the bottles. I have seen LD containers jammed, broken and the damage that can cause. This is not a regular occurrence, but it is a far more common event than an O2 bottle uncontained failure. What is a more likely event, an O2 bottle rupture due to an unnoticed mechanical failure or an incorrectly loaded and strapped down pallet allowing whatever is on it to move? Cargo hold sidewall panel blowout panels get dislodged regularly, O2 bottle explosions do not.

SUB

30th Jul 2008, 14:31

Just above the regulators on all of the bottles is the first officers back up aileron cables covered in grease.

TeachMe

30th Jul 2008, 16:56

Lots of comments about O2 on this thread. I wanted to clairify what most already know, O2 will NOT burn on its own. O2 needs a 'fuel' to oxidize. Without something to oxidize, no fire/explosion is possible.

Atmospheric O2 is about 21%. Even in a 100% O2 atmosphere most materials react no different to the naked eye. If anyone has seen Li, it is stored in a liquid (oil????) becuase if it contacts air, the 21% O2 is enough for it to 'burn', while the O2 in liquid is not enough and thus it is more stable.

The same is true in air. There are SOME materials that will self ignite in a 100% O2 atmosphere that do not in a 21% atmosphere. Chemically this comes down to more O2 molecules being able to 'touch' the surface of the material in a given time and thus raise the heat enough to 'sustain' the reaction. (over simple I know but gets the point across)

As a SLF with a first degree in BioChem, I know little of the chemical make ups of materials in the area of the 747 O2 tanks, but would be very surprised to learn any material used on an airframe itself would self ignite even in a 100% O2 atmosphere. I may be wrong, but that is a guess in part based on the very few materials that actualy can self ignite in a 100% O2 enviroment but are 'safe' in a 21% enviroment.

Thus the idea that a leak itself CAUSED an explosion is very unlikly. I can not see pure O2 contacting any material in an aircraft and thus causing a fire. The idea obove of an O2 leak causing a fire by 'touching' a fuel source (Hat on O2 tank in cockpit, O2 leak on rust inhibitor) seems very unlikly, but I would of course not deny it without testing/research. However, if a leak were present and thus an atmosphere with high O2 concentration existed, an ignition source would have a much higher chance of causing an explosion. From posts above, THIS DOES NOT SEEM to be the case.

I would suggest that whatever caused this sitaution is independent of the actual gas compressed in the tank. (unless caused by some interaction of the gas and tank/fittings itself).

TME

Edited to correct O2 concentration to 21% from 16% (16% is after breathing and a mix up from my CPR training :\ )