Qantas 744 Depressurisation
Join Date: Jun 2006
Location: Wellington, New Zealand
Age: 43
Posts: 51
Likes: 0
Received 0 Likes
on
0 Posts
pacplyer: I pretty much agree with you, but I think you still missed the point. That exploded car still shows how much damage one of those bottles can do -- it still takes a large force to blow a car apart like that even though they're not designed to be pressurised and have quite a different structure design compared to an airliner. And Boeings aren't built like tanks, as tanks are designed to withstand external compression, like a car 
Join Date: Aug 2007
Location: Alabama
Age: 58
Posts: 366
Likes: 0
Received 0 Likes
on
0 Posts
Repeat after me everybody: "If it's not Boeing, I'm not Going."
Is this the opinion of an expert?
A statement such this should be deleted from the thread as many other as being deleted. Such statement does not add anything to the thread discussion.
No facts to validate it, or...the a/c is falling apart but I am able to land it, that's a great a/c. Sounds good? not to me.
Note I am not saying anything about the a/c manufacturer...just commenting the post.
regards
Join Date: Jan 2008
Location: Sunny England
Posts: 26
Likes: 0
Received 0 Likes
on
0 Posts
I concur with #845, I in fact did an inspection very similar to this on a 744 today, in this job we try our very best to get to the problem (if there is one) before it gets to us.
Join Date: Jul 2006
Location: Germany
Posts: 44
Likes: 0
Received 0 Likes
on
0 Posts
pcplayer,
in post #844 you say:
Quote: They've repeatedly come home safe with huge portions of the aircraft gone. Unquote, followed by the name of an aircraft manufacturer.
Do you mean you'd rather go on an aircraft manufacturer's planes which repeatedly have developed holes (and come home safely) than on a manufacturer's planes who do not repeatedly develop holes (and come home safely(?
Sorry for thread drift.
in post #844 you say:
Quote: They've repeatedly come home safe with huge portions of the aircraft gone. Unquote, followed by the name of an aircraft manufacturer.
Do you mean you'd rather go on an aircraft manufacturer's planes which repeatedly have developed holes (and come home safely) than on a manufacturer's planes who do not repeatedly develop holes (and come home safely(?
Sorry for thread drift.
Last edited by Brakes on; 1st Aug 2008 at 22:18. Reason: spelling
Join Date: Jul 2003
Location: Australia
Posts: 157
Likes: 0
Received 0 Likes
on
0 Posts
Thank you r75 a point that has been missed by many. The very essence of our profession is to look to prevent a system failure that will cost lives. We rely heavily on testing,procedures,technology,science and experience. Each of these is important in what we call preventative maintenance. Those in the industry understand the term redundant system but even the maintaining of these systems follow the same principle. We don't just rely on the design, every element is important and that is why we will learn from this event and our experience and awareness will profit.
Join Date: Jan 2008
Location: UK
Posts: 36
Likes: 0
Received 0 Likes
on
0 Posts
Attn. Pacplyer post 830
Glad someone reads my posts!! I'd go further, actually. I think the top fitting of the bottle failed when the bottle was held in position. Why? Because the valve travelled on a vertical trajectory. This suggests that either
1. The assembly failed spontaneously; or
2. An item of baggage forcefully contacted the upper part of the tank assy when the latter was in its right and proper place.
The alternative — that the bottle was swinging around all over the place, and the valve assy took off at an angle that exactly compensated for the bottle's leanings — is too daft to contemplate.
My money is on option 1. — spontaneous failure of the cylinder-valve assembly.
1. The assembly failed spontaneously; or
2. An item of baggage forcefully contacted the upper part of the tank assy when the latter was in its right and proper place.
The alternative — that the bottle was swinging around all over the place, and the valve assy took off at an angle that exactly compensated for the bottle's leanings — is too daft to contemplate.
My money is on option 1. — spontaneous failure of the cylinder-valve assembly.
Join Date: Jan 2008
Location: UK
Posts: 36
Likes: 0
Received 0 Likes
on
0 Posts
Pick-up comparison
The fact that a Hilux is not designed to be pressurised is beside the point. Leakage of window- and door-seals when the world outside goes low-pressure is something that you experience over a matter of whole seconds. If pressure were built up gradually inside the truck it would leak out. But this is not what we are dealing with. An O2 tank takes a few milliseconds to fail. The pressure-wave from this event completely demolished the vehicle, a robust structure.
This incident also demonstrates that spontaneous failures happen. (I acknowledge that we do not know the history of this particular bottle.)
This incident also demonstrates that spontaneous failures happen. (I acknowledge that we do not know the history of this particular bottle.)
Join Date: Feb 2004
Location: Australia
Posts: 1,307
Likes: 0
Received 0 Likes
on
0 Posts
We don't yet know the oxygen pressure in the bottles before the event. Top pressure is believed to be 1800 psi and a recharge reportably required if 1300 psi or less. Ultimate design strength another unknown yet. Charge pressure could have been anywhere between 1300 and 1800 psi..
When filling the bottles at the remote fill port near the Forward Cargo door, the engineers use the gauge at the remote fill port to assess tank oxygen pressure. Although the cockpit indication is supposed to be a repeater (as it uses the same oxygen tank averaging system) the cockpit indications always read lower than the fill point gauge (+/-100psi difference is allowable), so the engineers have to put extra pressure in the tanks to get 1800psi in the cockpit. You might say that the fill point gauge is underreading, but this gauge reading is always closer to the gauge reading on the regularly calibrated oxygen servicing cart. Normally the fill pressure from the cart is higher still. I have, on occasions, on other operators, seen cockpit indications over 2000psi on warm days, so I can only imagine the pressures in the bottles on very hot days. I think the highest pressure I've seen in the cockpit on QF is in the mid 1900's (ex-Sydney).
Anyway, these pressures are all well below the design limits of the bottle and the pressure relief blow out disc value (2650~3083psi)
Join Date: Jul 2002
Location: On a park bench near an airport
Posts: 156
Likes: 0
Received 0 Likes
on
0 Posts
gauge reading is always closer to the gauge reading on the regularly calibrated oxygen servicing cart
I wonder if any other 'non-standard' maintenance has been carried out on QF -400 O2 systems that may have contributed to an O2 bottle failure?
Join Date: Nov 2006
Location: Asia
Posts: 183
Likes: 0
Received 0 Likes
on
0 Posts
SLF Here.
Is this the opinion of an expert?
A statement such this should be deleted from the thread as many other as being deleted. Such statement does not add anything to the thread discussion.
No facts to validate it, or...the a/c is falling apart but I am able to land it, that's a great a/c. Sounds good? not to me.
Note I am not saying anything about the a/c manufacturer...just commenting the post.
regards
Is this the opinion of an expert?
A statement such this should be deleted from the thread as many other as being deleted. Such statement does not add anything to the thread discussion.
No facts to validate it, or...the a/c is falling apart but I am able to land it, that's a great a/c. Sounds good? not to me.
Note I am not saying anything about the a/c manufacturer...just commenting the post.
regards
But there's nothing wrong with putting things in the form of a question as moderator Sick Squid has pointed out on stickies many times.But it's amazing to me just how many times the printed english language fails to convey intended meaning isn't it? I'll have to be more attentive to it.
Good point Soup, Airship and others. (Boeing tank; good one!
)Thanks for taking my barbs, everybody. The localized pressure wave of a cylinder exploding O2 tank is clearly is something you don't want in a confined space. Yes, it's a plausible theory imho.
And lastly, Conan the Barber is correct in his post.
I yield the floor to others.
pac
Join Date: Feb 2004
Location: Australia
Posts: 1,307
Likes: 0
Received 0 Likes
on
0 Posts
banana head said:
No, oxygen carts are filled with oxygen. Only nitrogen carts are filled with nitrogen.
Regularly calibrated, and for a time regularly filled with Nitrogen
Join Date: Apr 2008
Location: Sydney
Posts: 265
Likes: 0
Received 0 Likes
on
0 Posts
A few more photos of the door area in this article (u/f very shoddy quality) - experts go to work 
New pictures show interior damage to Qantas plane - News - Travel - smh.com.au
New pictures show interior damage to Qantas plane - News - Travel - smh.com.au
Join Date: Jul 2007
Location: Germany
Posts: 556
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by pasoundman
Originally Posted by NSEU
No, oxygen carts are filled with oxygen. Only nitrogen carts are filled with nitrogen.
Maintenance personnel used a nitrogen cart filled with nitrogen. No mixup there.
The problem was, they were using it to top up the oxygen tanks. And since the fittings didn't, well, fit, they exchanged them for ones that did.
Bernd
Join Date: Dec 1998
Location: .
Posts: 2,994
Likes: 0
Received 0 Likes
on
0 Posts
That's probably one of the reasons we don't fill from the charging point, pressure low change a bottle. So if QF charges from the remote point, the bottles could be sat in there for quite sometime then?
