Cracks found in A380 wing ribs
 

hello all just found this artical in the sydney morning herald Cracks found in A380s during Qantas repairs

Design margins are too thin these days as engineers try to save weight.

This is why DC6s are still in revenue service today. The margins were greater then, admittedly, as they used sliderules and not CAD programs.

Just a sign of the times, but I'm willing to bet there won't be ONE A380 still in revenue service 60 years after the last one rolls off the assembly line.

I don't think they will want a 380 to ferry sheep around in sixty years' time.

DC3s, 6s, and other aircraft are sometimes called "flying barn doors" - pretty hard to break a barn door!

DC-3/C-47
 

When I was flying air tours in the Otis Spunkmeyer DC-3s (C-41), I used to tell the passengers that the plane was designed before we had computers which told us how many times we could bend a piece of aluminum before it would break.

With the DC-1, Douglas built a wing and then drove a steam roller over it. The wing didn't bend or wrinkle, so the engineers figured that it was strong enough.

I thought the difference between good engineers and bad engineers is the ability to design to minimize cost and waste? Anybody can over design. What is the life cycle design parameters of an A380? Is it supposed to last 60 years?

I think it's supposed to last longer than 3 years

Sometimes it does pay to read an article before passing judgement:

Manufacturing error is of course no small matter, but it's quite a lot less hassle to rectify than a design flaw.

I clearly remember the A380 failing the wing loading test, it was news then the big delay became as a result of passenger service wiring!?! Fact is the wing barely made the grade (if there were not errors in the testing equipment) Expect more problems on this young aircraft!

So is this a manufacturing flaw?

There are essentially three types of cracks: Fatigue, stress-corrosion and acoustic fatigue. Each has a different mode of behaviour. Fatigue cracks typically grow perpendicular to major loads, while stress corrosion often grows parallel to the major loads, and acoustic fatigue grows in thin material often in a non-linear fashion (as buckling modes change). Fatigue is directly related to loads, so that is a design and certification testing issue. Stress-corrosion occurs at grain boundaries in rolled, forged or extruded alloys and is usually a heat-treatment or materials selection issue. Acoustic fatigue is related to buffeting and may be difficult to design and test.

Do we know what alloy was used and the directions the cracks are growing?

Storm, meet teacup

A380 Wing Cracks Not Affecting Operations | AVIATION WEEK

In sixty years...I expect this civilization to be living in caves and tending fires. In 2000 years, there will be another bunch of humanoids scratching their heads trying to figure out why the whole world is covered with concrete at least 45m wide and 3+ km long...:E

There is waaaaaaaay to much conjecture regarding this issue at this early stage. For a start, I don't trust most media outlets to report technical issues such as this completely or accurately. Do they have access to the inspection/defect reports raised by the technicians at the airlines affected or are they in possession of a service bulletin from the manufacturer or an airworthiness directive from an airworthiness authority ? Even the spokesman for the industrial organisation covering Australian licensed aircraft maintenance engineers (which the local media calls 'engineers', confusing them with professional engineers) is stirring the pot on this issue this morning berating the local national airworthiness authority for accepting the EASA position on the approach proposed by Airbus in dealing with this issue.

I find it interesting that the SMH article appears in the 'Travel Incidents' section of the 'Travel' pages. What on earth is a travel writer going to understand about airworthiness issues?

This has been all over the news on radio this morning downunder. Here's a more 'informed' article from the ABC, reporting feedback from various parties:

Qantas A380 among planes with wing cracks - ABC Melbourne - Australian Broadcasting Corporation

There's a little more useful information in this article.

It is only a manufacturing flaw if they were not built as designed and that was the cause of the problem, otherwise it is a design flaw. The real question is the cost of the repair now they say it does not limit the aircraft (time + weight + material cost).

Let's take a deep breath and read the description again carefully. Cracks have appeared in, "non-critical wing rib-skin attachments".

It is not cracks appearing in wing root box structures, a la F-111's. It is not cracks appearing in wing ribs. It is cracks appearing in wing-rib skin attachments.

When a wing flexes, as it does continously, it is inevitable that some minor cracking will appear in non-critical components attached to the wing structural components.
This is what is happening in this case. Nothing to see here, folks... move along.

Be more concerned about the composite components of the A380 that perform differently to metals... and which could be subject to decomposition and degradation over a relatively shorter period of time... as compared to the known and utilised metals in aircraft, that are inherently more stable, chemically and physically, over a far longer time frame.

A380 Cracks
 

From the Melbourne Age:

A380 cracks: check fleets now, say engineers

Anyone who has flown on a 380 and watched the wing bend and flex would have worries about how long this large piece of Aluminium that seems to have a strange bending moment about two thirds along it's length will last. Unlike other aircraft like the 747 which seems to have a uniform flexing of the wing along it's whole length the 380 has a totally different way of flexing so much so that I try to do my long haul flights to London on anything else except a 380. I hope that I am wrong but it looks like problems are just starting to appear.:eek:

Please explain further.

Wing flex
 

Have you seen the wings of the B787 in action? I guess you will not be flying that one either?

Ask any senior citizen

Flexible is good

BH - If you have non-structural panels attached to structural sections, and those non-structural panels are on the outer areas of the structural members, where the most lineal movement is encountered during wing flex; it's not unreasonable to expect those non-structural members to develop minor cracks, that are of no concern.
These cracks rarely propagate into safety-threatening levels, and the attitude of Airbus towards these cracks recently found, seems to be quite reasonable.
Let me know the aircraft that you examine or fly, that does not have one minor non-structural crack in it somewhere, after several thousands hours of operation.
The A380's are in commercial service, and racking up the hours. The facts remain, that the only problems encountered so far, have been the engines (supplied by an independent supplier)... and this minor, non-structural cracking.
In an aircraft that is a totally new design, and of such size and complexity, I would say that the performance of the A380 to this point in time, is outstanding.

@StallBoy:
 

keep being ignorant.
Boeing's don't crack, corrode or have other system/engine failures.:rolleyes:

Another nice wingflex video:

At least the 787 passed the load test the first time.

Bend Not Break: Boeing 787 Passes Wing Load Test - CBS News

Unlike the a380 like I had mentioned above and referenced here.

Airbus A380 test wing breaks just below ultimate load target


What was interesting is Boeing traditionally pushes the first one until it pops, mentioned in the first article b777/1994 at 154%. Sounds like they got what they wanted out of the 787 and called it a night. I would like to know what the B787 wing is actually capable of.

Onetrack, I was asking as you posted with a confident engineering outlook.
I have some basic engineering theory, but more a journeyman than a theorist.
After several thousand hours of operation I would expect to find minor cracking, even in structural components. The Airbus 380 in question did not have thousands of hours of operation.
One has carried out inspections on aircraft over the last several years and have not noticed cracking in the rib to skin attach on any.
Airbus do not consider it an immediate airworthiness isse which should allay safety concerns.
Cheers

The more tests the more you know and understand (these things have oodles of information collected)

With one succesful test you only know that it's good enough. With multiple tests you know by how much.

Of course the development time and money matter a little bit to the bottom line.

A quick sidetrack here - I have always been impressed by that China Airlines 747-SP that did the aerobatics over the Pacific. They pulled around 5G's twice and the wings were bent, but did not break.

lomapaseo,

In the aircraft industry, structural qualification tests are not really performed to collect data or to investigate how a particular component will respond to loads. Instead, the primary purpose of structural qualification testing is to validate the analysis used to design the component. As you noted, there is lots of data acquired during a structural test, and this data is used to improve the analytical models. A complex structure like an aircraft wing might be analyzed for 50 or more different load cases, but it is not tested for each of those load cases. I don't mean to discount the value of testing, but when an aircraft design is certified it is the analysis results that really count. The testing is really just a check to ensure that the analysis work was accurate.

As for structural cracks, there should not be any if the aircraft is maintained and operated within design parameters. However, aircraft structural designers acknowledge that cracks may occur for any number of reasons, and they perform detailed analyses just for these conditions. All critical aircraft structures have a Fracture Control Plan, which outlines how the structure will respond to cracks, how cracks will be prevented, and how cracks can be detected when they occur. Aircraft companies employ analysts specializing in fracture mechanics, as well as numerous QA and manufacturing process engineers to develop fracture control plans.

DTDHandbook | Guidelines for Damage Tolerance Design and Fracture Control Planning | Guidelines for Damage Tolerance Design and Fracture Control Planning

Airbus A380 should be grounded....
 

Not seen this anywhere before....
BBC News - Airbus A380 fleet should be grounded, say engineers

Aircraft crack . . . it happens.

Provided it's being monitored. It can't be that serious if there's a 4 yearly inspection/repair scheme.

It would seem that the Engineers who made these suggestions are working for the wrong people. They obviously know far more the the manufacturers so they should be some of their top people.
A simple phone call to Airbus would surely have them so excited about getting such experts to sort out any problems they may have.
Or maybe it should be left to those who designed and bulit the aeroplane.
They may be a tad better at making such a decision.
Airbus aren't stupid , they would make sure it was attended to immediately if they thought it necessary.
Maybe watching the cricket might be better than making these suggestions.
:=:=:=

This will be the same QANTAS engineers that hate the fact that their work is being outsourced to Asia. Axe and grind springs to mind alas.

TRUST ?
 

To those who proclaim, "trust the Manufacturer, they know best " and "trust the Regulator they're a Government Body", I'd say, yeah right.....United 747, Fwd Cargo door, PHNL, remember ?

Boeing and the NTSB didn't come out of that looking too flash.

"Cracks have been found on the wing ribs of at least three Airbus A380s belonging to Singapore Airlines and Qantas Airways.
Both carriers said the cracks were discovered in the 2nd quarter of 2011, and that they have been repaired and posed no danger to safety."

Sorry Jackneville, Qantas mechanic.

Sorry, I thought I was on A.net for a moment. :hmm:

As i understand it if structural damage is reported or found during a inspection then the SRM which is supplied by the manufacturer is the document that is the authoritive guide to engineers in dealing with that defect ,The SRM will state if the damage is within limits/ out of limits can be repaired/ cannot be repaired/ how it is to repaired ect.

Engineers no doubt use the SRM day in day out and i presume trust it to ensure aircraft remain airworthy, so whats different about this case? why do they suddenly not accept what airbus are saying, ie the damage is acceptable and repair can be defered

I think the above has a lot to do with all the media coverage of this matter. I recently saw a televised interview with an Australian based AME who was demanding that the aircraft be grounded - that kind of public posturing is quite uncommon in our industry.

Speaking for myself i have always found licensed maintenance engineers to be very down to earth ,dedicated, knowlegable people and certainly not the sort to cry wolf, if their concerned id be inclined to listen.
No doubt the moves to outsource work away from Oz is one which is causing emotions to run high and hardly suprising, if my job was being outsourced to Asia id be a tad concerned, but quite what that got to do with the point in question im not sure

spot on Topspotter, except where emotionalism over one's salary gets into it.

By the looks of this thread everybody's opinions are suspect by somebody.

Well since we can't just sit around expecting Gus at the corner bar to fix it, I guess we're going have to just let the system that we've got get on with it.

As long as Ted doesn't screw up, no worries.

http://img98.imageshack.us/img98/5318/wingsye5.jpg