STRESS Fractures in the A380

[VMC4ME]

I have it on good authority practically from the horses mouth that they have found stress fractures in the wing of the new A380.

Has anyone got any more info on this?

If it's 100% true then I'd be concerned about the consequences; not for the safety of the aircraft, but rather all the pending orders!

[Swanrider]

Would be keen to hear more, as some Australians have their new "Stress-detecting system" installed all over it. Millions of tiny silicon suction cup sensors in deep along all the ribs etc, feeding into a computer.:ok:

[tipsy]

I'm confused, since when does this A380 thingy qualify for "General Aviation":confused:

tipsy

[Sunfish]

Tipsy, because the cabin crew use Cessna 172's to get from one end of the cabin to the other.

I'm concerned about the use of the term "stress fractures" in this context. Do we mean cracks?

[Woomera]

Sunfish would appreciate an idea about the difference between a "stress fracture" and a "crack".

Are they interchangeable terms, does one follow the other and/or in which order?

[VMC4ME]

Did anyone do physics?

From a basic perspective... from somoene with no idea.

I guess a crack could be caused by anything and could appear anywhere... say a crack in paint caused by movement of parts, physical damage or a whack. Not necessarily caused by stresses in the aircraft.

Stress Fractures you could say are caused by "stress" of components, moving wings, poor design, un-due stress...

Perhaps in summary a crack could be caused by an event, where-as stress fractures can be caused by undue forces?

Breaking your arm / leg - A break is a clean break where you essentially snap the bone, whereas a green-stick fracture is where you crack the bone. This means nothing in relation to an aircraft, however it sounds good.

[FO Cokebottle]

sooooo...

I guess we can replace showing "plumber's crack" with "plumber's fracture" then :D

[Deaf]

Never heard the term "stress fracture" used in relation to engineering materials.

Googling for a definition it appears to be a medical term for a bone fracture caused by repeated stress. Crudely it appears to be related to fatigue cracking although the mechanism is uncertain. This is probably due to the difficulty (practically and ethically) of conducting controlled experiments in living organisms.

[J430]

So now that we have thrashed out the words of the day on Sesame Street, can we get back to any gossip on the A380 having any form of fracture, cracks, parts delaminating, falling off or otherwise not in the state of which its dessigner intended?

This might be a big deal if its true! Now how late are the deliveries going to be?

[Deaf]

I would be surprised if there were not problems of this type.

Where there is a weight critical assembly of a complex structure and loading computer analysis can only take you so far. This is the case with metals which are istropic and relatively well understood. So we have structural test prototypes and fatigue testing.

Where composites are concerned reading through things like reports of conferences and the like give me the impression that there is quite a bit of trial and error ie design, build break redesign etc. This is before we get into issues like quality control, repair etc.

Having said that,

1. Increasing use of composites is the way of the future (specific stiffness if no other reason)

2. Boeing are likely to have the same problems with the 787

3. If these sorts of thing don't happen at the prototype stage then the thing is probably too heavy.

[Chimbu chuckles]

Received an email recently from an Air NZ mate with pictures of the centerbody gear bogies on the A380...seems Airbus didn't bother with center body steering like the 747 to save weight etc...result is some pretty scary tire sideloads/scubbing and tarmac carnage.:ouch:

Might have been a mistake in hindsight?

[donpizmeov]

Chimbu Chuckles,
I think if you get bored and do a search around here, you will find that the pics are a results of a test, where a tug dragged the thing around the tarmac in ever decreasing circles. It seems to have past the test. The informative write up on said email, is total crap.
But hey, that should not be allowed to stop a good rumour.

Don

[QNIM]

Gday VMC4ME
I think you shouldn't just listen to the horse's mouth but check out the rear coz it's probably got BOEING stamped on it's arse.
Cheers Q :p

[VMC4ME]

Unfortunately it's all true... have heard a little more about it. Should be sorted out shortly.

[Sunfish]

Anyone remember the F27? Its landing gear had a cracking problem too when it was new. The solution was to put bloody big holes in the top of the struts so that there was no metal to crack!

[AcroAce60]

I can remember one potential customer saying he'd buy one of our aeroplanes if we'd remove the strut. It'd get in the way of his photography. Something to be said for removing anything that breaks but I wonder what will break instead. Another potential customer was more practical - he was a big man so wanted the whole aeroplane 10% oversize.
While I'm here, might as well mention the use of Glare on the A380 - metal/composite - although not used in the wing, has significantly improved fatigure properties.
From Swanrider, that SMS method of CVM is really good, and good luck to the company. It should be used on every aeroplane where there's a jesus bolt.