metal fatigue on Qantas jet?

[lazeyjack]

Taking a look at the 747, it seems to me, as tho there has been a crack starting from metal fatigue, note the clean break, and then the tearing of the other in the pressure hull
I am not familiar with the structure, but it looks like there is an inner skin, outer hull with t sections ring frames and stringers
interesting, never happened before here on a 747
Fatigue in aircraft structures has been well studied, and thats where I am taking a guess to the cause of this
Wonder why was not picked up? although fatigue does not show until the failure usually But cracks can start and wonder why if they did, was not picked up
what do you think>

[Petros]

I used to work for Boeing doing structural retrofit desgin. That location is just ahead of the the bulkhead that forms the wing box section, there is no equipment as I recall there, it is just part of the forward cargo hold (you can see the luggage exposed through the hole).

The outter skin is just a fiberglass fairing that fairs the structural fuselage skin to the wing root, it is not primary structure and it would just blow off if the pressurized hull would fail here.

The airframe goes through periodic teardown and inspections with the max fatigue life of the skin, frames, stringers, etc. in mind. So you are correct this should have be caught if it was simply a matter of routine fatigue failure. Quantas has a pretty good reputation with skilled mechanics and a good maintenance program, though it is possible something was missed. Though that is unlikely, you do not see this kind of failure in a 747, which has a pretty robust struture, especialy at this location where the wing root attaches to the fuselage.

It is possible someone packed something imporper into thier luggage, like a porpane stove cartrage or something simmar. Or even a possible terroist's failed attempt to bring down the liner by packing an explosive device in the luggage.

An investigation will tell, it may take weeks. but the strucutre is designed to be "fail-safe" meaning that you can loose skin panels, frames, or stringers and there are tear-stops built into the skin, to prevent the whole structure from blowing open. IT looks like the design worked as intented, a small failure did not result is a catastrophic failure. The design took the damage yet it saved the passagers and crew, as well as the aircraft.

[Guest625101138]

I have inspected a QANTAS 747 stripped down during a major overhaul. The two things that left a lasting impression were the level of corrosion around the galley/toilet areas where liquids run down into panels and the "swiss cheesing" of the door frames to stop cracks propagating. At that time they used about 1/8" drill hole right at the root of the crack. I have no idea if this is still what is done or how long they keep drilling before the frame gets replaced - if ever.

It will be interesting to see the outcome. Did you know it was the plane that took the Pope home?

Generally QANTAS 747s are long haul so the heavy cycle loading is not as frequent as short haul aircraft. That said I have had a couple of rough rides over the Pacific in the past few months. Seems to be worse than I remember but maybe just getting old or you notice it more when you are laying down.

Rick W.

[lazeyjack]

intersting guys,
If you get a chance read Shutes novel the whole thing is based on a failure of a tailspar, due to fatigue, and the scientist who built the test rig to simulate the loads frequencys on the spar and tail
Yes even marine alloys hate human waste, thats why we paint inside the tanks
Shutes NO HIGHWAY
So the outer skin is all grp, , I never knew that---I used to admire the nosecone, , I no longer will!!
that Pope, cast a spell over her!!
just read where Qantas (engineers) said they saw (lots) of corrosion on recent cabin refit< are these the same people who are bleating abt Qantas taking maintenance offshore? and saying "hey thats's unsafe

[Petros]

The investigation is not over yet, but I notice in the news accounts they are calling it an "explosion" rather than a hull failure.

[Guest625101138]

Originally Posted by Petros

The investigation is not over yet, but I notice in the news accounts they are calling it an "explosion" rather than a hull failure.

An oxygen cylinder is the likely cause:
http://www.radioaustralia.net.au/pro...7/s2316128.htm

There are almost daily incidents on QANTAS planes at the moment and the issue of outsourcing maintenance is coming under close scrutiny. Could be you get what you pay for. An aircraft maintenance firm somewhere in SE Asia may not be as protective of QANTAS's safety record as their own employees based in Australia.

The frequency of serious events is getting to the level where you could expect something catastrophic. It would seem systemic rather than isolated incidents but then it is a hot issue and maybe we are just getting more press on it. I am aware of minor incidents that have not been reported in the press before.

Rick W.

[lazeyjack]

wonders
steel or al al O2 bottle, in test, out of test?