Cracks found in A380 wing ribs

[rampman]

hello all just found this artical in the sydney morning herald Cracks found in A380s during Qantas repairs (http://www.smh.com.au/travel/travel-incidents/cracks-found-in-a380s-during-qantas-repairs-20120105-1pmyv.html)

[zerozero]

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.

[fantom]

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

[rotornut]

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

[Robert Campbell]

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.

[mtwittm]

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?

[Robert Campbell]

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

[SMT Member]

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

The cause of the cracks in the Nancy Bird-Walton's wing is still to be determined but an initial assessment is believed to pin the blame more on the way the wing ribs were constructed rather than due to the loads and thrust at which the aircraft was operated by Qantas.
Read more: Cracks found in A380s during Qantas repairs (http://www.smh.com.au/travel/travel-incidents/cracks-found-in-a380s-during-qantas-repairs-20120105-1pmyv.html#ixzz1icZZLvDL)



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

[grounded27]

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!

[blackhand]

initial assessment is believed to pin the blame more on the way the wing ribs were constructed rather than due to the loads
So is this a manufacturing flaw?

[blakmax]

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?

[SMT Member]

Storm, meet teacup

A380 Wing Cracks Not Affecting Operations | AVIATION WEEK (http://www.aviationweek.com/aw/generic/story.jsp?id=news/awx/2012/01/05/awx_01_05_2012_p0-411418.xml&headline=A380%20Wing%20Cracks%20Not%20Affecting%20Operations&channel=comm)

[click]

there won't be ONE A380 still in revenue service 60 years after the last one rolls off the assembly line.
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

[A30_737_AEWC]

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 (http://www.abc.net.au/news/2012-01-06/minor-cracks-found-on-a380-wings/3760656/?site=melbourne)

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

[Phalanger]

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

[onetrack]

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.

[pgrwrx]

From the Melbourne Age:

A380 cracks: check fleets now, say engineers (http://www.theage.com.au/travel/travel-incidents/a380-cracks-check-fleets-now-say-engineers-20120106-1pnr6.html)

[StallBoy]

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:

[blackhand]

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.
Please explain further.

[KiloMikePapa]

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.

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

http://www.youtube.com/watch?v=Dscn0rFvukg

[lomapaseo]

Ask any senior citizen

Flexible is good

[onetrack]

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.

[A33Zab]

I try to do my long haul flights to London on anything else except a 380

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

Another nice wingflex video:

http://www.youtube.com/watch?v=WFEs-DatuHs&feature=sub

[grounded27]

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

Bend Not Break: Boeing 787 Passes Wing Load Test - CBS News (http://www.cbsnews.com/8301-505123_162-43641624/bend-not-break-boeing-787-passes-wing-load-test/)

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

Airbus A380 test wing breaks just below ultimate load target (http://www.flightglobal.com/news/articles/airbus-a380-test-wing-breaks-just-below-ultimate-load-204716/)


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.

[blackhand]

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.
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

[lomapaseo]

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


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.

[18-Wheeler]

I would like to know what the B787 wing is actually capable of.

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.

[riff_raff]

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.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 (http://www.afgrow.net/applications/DTDHandbook/Sections/page10_0.aspx)

[halwise]

Not seen this anywhere before....
BBC News - Airbus A380 fleet should be grounded, say engineers (http://www.bbc.co.uk/news/business-16452878)

[Dengue_Dude]

Aircraft crack . . . it happens.

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

[RodH]

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.
:=:=:=

[Skipness One Echo]

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.

[Jackneville]

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.

[oldchina]

"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.

[11Fan]

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

[Topspotter]

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

[V1... Ooops]

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.

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.

[Topspotter]

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

[lomapaseo]

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.


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.

[11Fan]

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

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

[grounded27]

"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."

Ridiculous to find cracks this soon in operation, sounds like they were found during routine phase maintenance and will likely be found in the same general area on all A380 manufactured to date.

The way a wing used to be built was to stress, inspect, beef up and repeat.

Like I mentioned before Airbus had engineered this aircraft to the tightest weight restricting tolerances they could, the largest indication of this was their failure to meet the initial wing load testing. I can not find word one on the INTERNET about their solution and the successful test that deemed the wing capable. It was big news one day.. And then the big delay due to cabin entertainment wiring pushed the aircraft delevery schedule MONTHS! This was all you could read about day after day!!!!

I am sure there is no serious risk but this will mean beefing up those ribs, this will probably result in creating another stress point, beef it up and so on until the aircraft weighs more than they would have been happy selling it for in the first place.

Who knows I could be wrong, time will tell. You can be damn sure Airbus and their customers will keep it as quiet as possible though.

[A33Zab]

:ok:
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.

and if it is not in the SRM, the Airbus design office needs to be contacted before any further flight,
conservative is very progressive compared to the Airbus design office, they don't take any risk.

So no worries about the Airbus statement!!

However since it is the media now, they need to publish detailed information and solution(s) to re-establish the trust to the public.

[PA-28-180]

Re Wing flexing......I remember an episode of wings once that included the Galaxy 5A......you should see THAT one. If I remember right, there is a system to 'dampen' the flexing....when they turned it off, it looked like the d@mn thing was flapping it's wings like a bird. Perhaps Galaxy flyer could confirm this....? Actually, the only thing that bothers me about this problem is that the aircraft are basically brand new, and this is showing up already. I understand with a new design that there are always 'teething pains'.....but this situation is rather surprising. It will be interesting to see what comes next.....

[mitrosft]

Was it the reason to have 4 out of 8 Lufthansa's 380s in the hangar (2 inside 2 nearby) in EDDF on Dec 28th when we were landing from LHR ?:eek:

[lomapaseo]

grounded27

'.......sounds like they were found during routine phase maintenance.....

This one part of your response may not be correct.

I believe the cracks were found on the wing that suffered the uncontained engine failure during the extraordinary repair work.

[streetcar driver]

Lack of flights between Christmas and New Year's Eve.

[misd-agin]

Could you imagine the news, and passenger reactions, if the headline said "Cracks causing fuel leaks" and pilots/engineers started posting "that's unsafe and I wouldn't fly it"?

Well, that exact situation(cracks causing fuel leaks) occurred. Fuel leak was a known issue and tracked.

The whole 'what, where, when, why' for any crack needs to be understood.

[Reinhardt]

To the best of my knowledge, the wings are built in England
(southwest of MCT, just passed the border with Wales)

[lomapaseo]

The whole 'what, where, when, why' for any crack needs to be understood

Absolutely :ok:

and it is by the professionals, else the regulator wouldn't let it fly

[John Farley]

Clearly to some PPRuNers cracks found on the ground early on in an aircraft's career are big bad news.

To engineers they are a beautiful confirmation of the fail-safe aspects of the design.

[grounded27]

Airbus indeed must have their hands full. Better to catch something like this sooner than later. Did fuel leaks or a battered wing due to the engine failure or both drive someone into those tanks?

[Serafim Kamoutsis]

Only as a joke is acceptable the declaration the Aviation Week!!!

[Abbey Road]

Only as a joke is acceptable the declaration the Aviation Week!!!


Sorry, Serafim, whilst I realise that English is probably not your primary language, your post makes absolutely no sense.

[grounded27]

Hope you did not mis-read my post. From what I get the aircraft that were found with cracks in the ribs were not due to routine maintenance. I would like to confirm that the initial investigation into the wings were as a result of fuel leaks and possibly the un contained engine failure probably causing damage to the lower wing skin. If this is true, un-scheduled maintenance found this serious problem that will likely be found on most A380's in service if they decide to look.

[mat777]

In light of the daily fail putting up ANOTHER article about this, someone has now commendted on it:

"Cracks in any metallic frame are a sign of failure..... IT IS NOT METALLIC... It is composite Fibre.... It is also in an area of brackets that are there for production purposes... If it was possible to take these out after the wing is finished they would have done... They have no Structural Component to the finished plane.... It has been stated over and over again... Airbus say its safe, the bodies that regulate aircraft say its safe. The conspiracy theorists are have a field day over this"

Is this true about the location and importance or are they talking rubbish?

[ilesmark]

BBC News - A380 wings to be checked for cracks, EASA says (http://www.bbc.co.uk/news/business-16649334)

Anyone seen this article on today's BBC?

[flydive1]

EASA Airworthiness Directives Publishing Tool (http://ad.easa.europa.eu/ad/2012-0013)

[infrequentflyer789]

EASA Airworthiness Directives Publishing Tool (http://ad.easa.europa.eu/ad/2012-0013)

"Following an unscheduled internal inspection of an A380 wing"

Well, I guess that's one way to describe aftermath of QF32 :D

[Topspotter]

Source of mine tells me they suspect faulty heat treatment of the material in certain batch numbers during manufacture may be the problem, whatever the case im sure it will be sorted quickly

[grizzled]

As the Aviation Herald says, the AD issued today reads exactly like an Emergency AD -- though EASA isn't calling it that.

News: Airworthiness Directive regarding Airbus A380 wing cracks (http://avherald.com/h?article=44992a89&opt=0)

If it walks like a duck, and quacks like a duck...

:rolleyes:

[Rollingthunder]

A380 wings to be checked for cracks, EASA says Airbus said there was no immediate threat to safety. (maybe later then)

Twenty Airbus A380s will have to undergo checks for cracks in their wings, the safety regulator has said.

The European Aviation Safety Agency (EASA) said the planes, a third of the current fleet, would undergo a "visual inspection" for cracks.

A few planes, which have carried out more than 1,800 flights, will need inspections within four days, it said.

Airbus said the cracks were not an immediate threat to safety. If cracks are found it will carry out repairs.

The problems could affect planes operated by Singapore Airlines, Emirates and Air France.

Cracks

The agency said it has determined that the cracks may develop on aeroplanes after a "period of time" in service.

"This condition, if not detected and corrected, could potentially affect the structural integrity of the aeroplane," said the agency in its directive ordering the inspections.

This is the second set of cracks found on A380 wings.

The first, which were less serious, emerged during repairs to a Qantas A380 following a blowout of its Rolls Royce engine in November 2010.

That prompted more widespread investigations and more serious cracks were found in the UK-made wings on Thursday.

If more, similar, cracks are found aircraft may be grounded in order to carry out a repair programme agreed between Airbus and regulators.

Repairs

Only planes which have carried out more than 1,800 flights are being targeted urgently, those which have flown between 1,300 and 1,800 flights must be tested within 6 weeks.

"Airbus confirms that during routine inspections some additional cracks have been found on a limited number of non-critical brackets (known as rib-skin attachments or wing rib feet) inside the wings of some A380s," the company said in a statement.

However EASA warned further steps may be needed.

"As a result of the on-going investigation, further mandatory action might be considered."

(manager tech ops, me)

[Viking101]

It's weird.

Brand new aircraft, top engineering and latest technology.

Cracks in the correct places that are expected is one thing, especially after years of service.

But this is different. Very different. Airbus didn't expect them, and their official statement makes me think they are as surprised as the engineers seeing them for the first time.

I am sure they will all be grounded until thorough checks and tests has been done, together with necessary repairs... And this will cost Airbus more money and reputation.

There is nothing like a reliable and safe Boeing.

[twochai]

My understanding is that the cracking issue is an assembly problem, neither design nor fatigue related. No design changes required, but more careful attention to assembly processes to avoid pre-loading the structure.

[jcjeant]

Hi,

So .. this is a minor problem ... :ok:

Further to this finding, inspections were carried out on a number of other
aeroplanes where further cracks have been found. During one of those
inspections, a new form of rib foot cracking originating from the forward and aft
edges of the vertical web of the rib feet has been identified (Type 2 cracks
according to Airbus AOT terminology). The new form of cracking is more
significant than the original rib foot hole cracking. It has been determined that
the Type 2 cracks may develop on other aeroplanes after a period of time in
service.
This condition, if not detected and corrected, could potentially affect the
structural integrity of the aeroplane.
For the reasons described above, this AD requires a Detailed Visual Inspection
(DVI) of certain wing rib feet. This AD also requires reporting the inspection
results to Airbus.

[infrequentflyer789]

Hi,

So .. this is a minor problem ... :ok:

My gut reaction is that it is less of a problem than turbine disks which like to go out and get some fresh air by way a high speed transit through the wing...

[twochai]

Stop fretting, the boys are on it!

[zerozero]

My gut reaction is that it is less of a problem than turbine disks which like to go out and get some fresh air by way a high speed transit through the wing...

Well, let's be fair.

That engine came apart thanks to a failed oil seal.

But it's like they say: One structural failure can ruin your whole day (cracks or shrapnel? Who's counting?)

:bored:

[SassyPilotsWife]

so.. does this mean that my seat on the upper deck of an A380 on Tuesday out of CDG might not have me in it ?

Would you guys be calling the airlines asking for a change of intinerary ? Now im not so excited about the nice upgrade I got. I mean don't get me wrong.. I'm happy to go to Heaven, but not via hitting the ground ( or water) first!

[zerozero]

I've ridden the A380 (LH) and I would do so again.

The taxi ride to the airport is still the most dangerous part of the journey.

:)

But still, we need to call a spade a spade.

Bon voyage.

[AN2 Driver]

Sassy,

by that time, Tuesday, the most affected airplanes should not be flying anymore. Possibly, however, you might find yourself on some other airplane if too many of them are in the check and therefore not available.

Whether to rebook or not in the end you have to make that decision. I don't think any airline right now would blame you.

Novelty is always interesting but one has to remember that while the early bird might get the worm, only the second mouse gets the cheese!

[flying.monkeyz]

The European Aviation Safety Agency has issued a directive requiring precautionary checks on brackets within the wings of certain Airbus A380 aircraft. We are liaising closely with Airbus and are carrying out inspections in full compliance with the directive.


As checks are being carried out, some flights normally operated by A380s will be temporarily operated by other aircraft. We apologise for any inconvenience caused.


Affected flights at this stage will include SQ346 from Singapore to Zurich and SQ345 from Zurich to Singapore, on 24 January, 25 January and 26 January. Flights over these three days will be operated with Boeing 777-300ER aircraft. There is no change to scheduled departure and arrival times.


Singapore Airlines will waive administrative fees/penalties for refund, rebooking or re-routing, for customers holding confirmed tickets issued on or before 21 January 2012, for travel on SQ346/345 from 24January 2012 to 27 January 2012, both dates inclusive. This also applies to KrisFlyer redemption tickets.


The safety of our customers and crew is our number one priority and we will ensure that we take whatever action is needed for the continued safe operation of our Airbus A380 fleet.


For contact details of our offices around the world, please click on the following link: Singapore Airlines (http://www.singaporeair.com/en_UK/contact-us/)

[Bergerie1]

Can anyone post some pictures or diagrams of the wing components that have cracks in them. I would like to know exactly where they are. Many thanks.

[Machaca]

http://i337.photobucket.com/albums/n385/motidog/A380wingrib1.jpg

The cracks (less than 1cm long) were found on the feet of the wing ribs. The feet attach the rib to the wing skins.

Airbus has traced the problem to the 7449 aluminium used in the wing ribs. 7449 is more sensitive to the way the parts are assembled on the wing. They ruled out flight loads or fatigue as causes.

http://i337.photobucket.com/albums/n385/motidog/A380wingAssembly1.jpg

A few years back, Machine Design (http://machinedesign.com/article/servosystem-deftly-handles-airbus-wings-0303) reported:

Servosystem deftly handles Airbus wings
MARCH 3, 2005 Staff

With a span nearly as long as a football field at 261 ft, producing a single Airbus A380 wing involves precisely positioning a massive structure to drill, rivet, and bolt approximately 180,000 holes.

During wing manufacturing, six servohydraulic axes move panels measuring up to 111 ft long and weighing 8,818 lb.

That presented a significant challenge for Airbus' manufacturing team in Broughton, U.K., and Electroimpact Inc., Mukilteo, Wash., the prime contractor for wing-assembly automation tools.

Wings are a structural framework of spars and ribs covered with metal panels. The panels consist of a curved, aluminumalloy skin reinforced by stringers that ensure shape and strength. The tricky part is moving assembled panels into four-story high jigs holding the ribs, spars, and leading and trailing edges, for subsequent assembly and fastening.

The huge size and flexible nature of a completed panel — up to 111-ft long and weighing 8,818 lb — creates a motion-control nightmare. According to Electroimpact's Ted Karagias, handling a wing panel with multiple support points isn't easy. Cranes won't work because the panels distort when suspended, he explains. "Basically you have a statically indeterminate system. The panels twist, bend, and kick as they react to the forces introduced by lifting equipment," he says.

To overcome this problem, Electroimpact devised a manipulator with six coordinated servohydraulic arms to maintain the panel's proper form and precisely control position. "Two of the six arms control the panel's vertical position," he says. "The other four act as slaves imparting a constant programmed force on the wing panel. That way, when the positioning arms are commanded to move up or down, the load-seeking arms follow along to maintain the panel's form."

Each panel-loader arm has four hydraulic-driven axes plus one passive axis, requiring the simultaneous coordination of 24 axes.

[grounded27]

Airbus has traced the problem to the 7449 aluminium used in the wing ribs. 7449 is more sensitive to the way the parts are assembled on the wing. They ruled out flight loads or fatigue as causes.

My guess is that 7449 is lighter than the other stuff. What a disaster, it looks like the ribs and the feet are one single milled piece (pos). Not much of a sheetmetal guy but this does not seem like a simple fix.

[no-hoper]

I think you are right about the metal ribs.On the carbon ribs the rib feet are riveted.
Check Machacas first picture upper rh corner.

[TZ350]

Aluminum Alloy Development for the Airbus A380 :: KEY to METALS Article (http://www.keytometals.com/page.aspx?ID=CheckArticle&site=ktn&NM=227)

[Turbine D]

7449 alloy is basically aluminum + 8.1% zinc and a minor percentage of a few other elements. From what I have read, the molten alloy is cast in the form of large plates from which the ribs are milled to the desired configuration. Heat treating consists of a solution treatment, tempering treatment followed by an over-aging treatment. This gives the alloy higher tensile strength and modulus verses older aluminum alloys. These properties enable the panels to be designed and subsequently milled to thinner cross sections thereby reducing weight.

My guess would be that the cracks first found in holes of the feet could have been a manufacturing problem where the sharp edges were not radiused to the desired specification in some panels. Holes in structural components are significant stress risers points where small cracks can develop under stress and cycles at sharp corners or edges.

The initial assembly of these A-380 wings is a real engineering achievement!

[Bergerie1]

machaca; many thanks.

I can remember seeing cracks in VC10s, 707s and 747s, even though some of them looked alarming the engineers involved were usually very sanguine! But the structural engineering seemed rather simpler in those days.

I only flew them and hoped never to break them.

[911slf]

I am a non pilot and a non engineer.

Would it be fair to say that the worst case scenario is that:



time consuming and expensive checks will need to be carried out
expensive repairs will be required
these will add weight
this will involve the manufacturer suffering financial penalties from customers


Does anyone assert it will be worse than this?

[no-hoper]

How the Wing is build :
Removed due to no relation to this thread.

[grounded27]

How the Wing is build :

What does this have to do with the failure? Nothing!!!! 7449 alloy has failed in the desigh spec.. This is fact. I want to hear what the resolution is.

[lomapaseo]

I am a non pilot and a non engineer.

Would it be fair to say that the worst case scenario is that:


time consuming and expensive checks will need to be carried out
expensive repairs will be required
these will add weight
this will involve the manufacturer suffering financial penalties from customers

Does anyone assert it will be worse than this?


Experinece is that the result will land someplace between worst case and best case.

Does anybody have a best case scenario as well?

[no-hoper]

Ok.The movie was deleted.We have experts around to proceed on a more professionell level.




"Not much of a sheetmetal guy ..."

[Fargoo]

Ok.The movie was deleted.We have experts around to proceed on a more professional level.




"Not much of a sheetmetal guy ..."

Shame you removed it, it did actually add to this thread and showed the parts in question quite clearly. :ok:

[Turbine D]

grounded27

What does this have to do with the failure? Nothing!!!! 7449 alloy has failed in the desigh spec.. This is fact. I want to hear what the resolution is.

There is some ambiguity in my mind relative to your proclamation. Do you mean:
a. The 7449 alloy was either off chemistry or improperly processed during subsequent heat treatments?:eek:
or,
b. The rib structure made from the alloy was marginally designed to the point the capability of the alloy was exceeded by stress levels being experienced in service?:uhoh:

Please clarify if you would, thanks,

TD

[grounded27]

The alloy AND thickness of the rib feet was insufficient for the application. I am saying that if 7449 is a good alloy for this application there was not enough for it. If it was not it is obviously the wrong material for the job. The bottom line is that Airbus was going for weight savings in this monster of an aircraft and is now paying for a poor decision.

[TZ350]

Higher Levels of Automation Lift Productivity for Airbus A380 Wing Assembly Process (http://www.ien.com/article/higher-levels-automation/13788)

[rampman]

here is an update to the thrade from the sydney morning herald :ok: rampman

More A380 wing cracks found: sources (http://www.smh.com.au/travel/travel-news/more-a380-wing-cracks-found-sources-20120125-1qgdy.html)

[Turbine D]

grounded27,

The alloy AND thickness of the rib feet was insufficient for the application. I am saying that if 7449 is a good alloy for this application there was not enough for it. If it was not it is obviously the wrong material for the job. The bottom line is that Airbus was going for weight savings in this monster of an aircraft and is now paying for a poor decision.


Thank you for responding and answering my questions.

First, I am reposting the video of the A-380 wing assembly process as I think it is significant. Particularly, at the times of 7:24 & 8:00, stop and look at the brackets, also known as rib feet. For each wing, there are 2,000 of these. Each wing has 62 ribs, 38 are metallic and 24 are carbon composite. The wing panels, some are very long, are creep formed to the desired contour of the wing surface at the location they will be fastened to. The rib feet of the top of the structure is designed knowing it will be in compression during actual service. The rib feet on the bottom of the structure that you cannot see are designed to be in tension and I would bet they would be different, more robust. The alloy, 7449-T7651 is a new alloy that contains no chromium unlike other 7XXX series alloys or older aluminum alloys. The T7651 condition stands for an over tempering heat treatment. This is done to maximize improvement of corrosion resistance during service. This comes at some sacrifice of other properties. What is important to understand is the significance of the assembly orientation and the possible stresses put on the rib feet that would not be realized in service.

Airbus has indicated the following:

Justin Dubon, an Airbus spokesman, said the company had established an inspection and repair procedure in coordination with the safety agency to address the cracking, which he said was linked to unforeseen stresses placed on the wings during the manufacturing process and not to a design problem.

“Both types of cracks have been traced to the manufacturing process, and those practices have now been changed,” Mr. Dubon said. All of the A380s’ wings are built at an Airbus plant in Broughton, Wales.

The first cracks were found late last year on the wing of a Qantas A380 that was being refurbished after experiencing a spectacular midair engine explosion in 2010. Airbus deemed the cracks — which extend from a bolt hole in the bracket — to be “noncritical” and advised airlines to inspect and replace the parts during routine scheduled four-year maintenance checks. The first A380s entered service four years ago.

This statement does make logical sense. The first cracks found, extending out of the bolt hole were, IMHO, coming from sharp corners. In a compressive tensile state, they would not grow very fast and would not necessarily be of grain boundary nature. Their rate of growth could be predicted and a time set for when repairs could be carried out without jepordizing safety.

The other cracks are not on the feet per-se, but on the shape below the feet in between the rib structure and the feet. These are more serious and IMHO, would be grain boundary cracks that could extend quickly depending on grain boundary length. With the orientation of the feet and the wing panel during assembly, it may be possible to unevenly stress this area depending on the force being supply to press the panel to the feet verses the weight of the panel and the sequence of bolt insertion and fastening.

Since we don't know the location of the troubled rib feet, and if the troubled feet are repeatable from wing to wing, aircraft to aircraft, it is hard to know for sure. But IMHO, the assembly process does have something to do with this, more so than thinking the ribs are under-designed. We will see as more information evolves.

TD
Airbus A380 - Wing Construction - HD - YouTube

[Machaca]

Since we don't know the location of the troubled rib feet, and if the troubled feet are repeatable from wing to wing, aircraft to aircraft, it is hard to know for sure.

On Jan. 6th, Charles Champion, Airbus head of engineering, stated while discussing the cracks "We found it is very random. We actually found them on ribs across the wing and from one aircraft to another it can be a different rib foot."

"On some aircraft we found almost none and on others we found several across the wing on both sides."

[Machaca]

the assembly process does have something to do with this, more so than thinking the ribs are under-designed

On Jan 20 AW&ST reported:

The new cracking is slightly different and viewed as more significant, though. It has been seen on two A380s that were being scrutinized. The damage was spotted when a customer aircraft underwent a C check within the last few weeks. One of the brackets—on its vertical part—had a more significant crack than the original hairline stresses, prompting Airbus to notify safety authorities and to launch a wider inspection of nine aircraft; evidence of cracking was found on a second aircraft.

As part of the root cause analysis, Airbus instrumented one of its own aircraft to assess whether the company’s original wing load estimates were faulty. It was determined that was not the case. The likely cause was found in the assembly process, in which too much stress is applied to the bracket when the wing skin is attached to the rib. The part itself is not being redesigned, but the assembly process is being changed as a long-term solution.

[no-hoper]

Hi Turbine D,

Thanks for your post,some additional infos from my side.
" Each wing has 62 ribs, 38 are metallic and 24 are carbon composite."
Your amount is correct but officially they are talking about 23 CFRP and 49 in total.The difference comes from a center spar from rib 2 to 17.So these ribs
are half ribs but counted as one.Ref video at 7.12.

" The rib feet on the bottom of the structure that you cannot see..."

This is the opposite way.The installation of the panels in the video is showing
the bottom surface.You can identify the bottom by the man holes.

[blakmax]

OK, so the video clearly shows a vacuum bag and autoclave procedure. Are the ribs bonded to the skins? Are the composite ribs cocured or secondary bonded? Are the metallic ribs bonded?

The other cracks are not on the feet per-se, but on the shape below the feet in between the rib structure and the feet. These are more serious and IMHO, would be grain boundary cracks that could extend quickly depending on grain boundary length.Grain boundary cracks are usually stress corrosion cracks. The clarifying evidence comes from the direction of cracking. Any designer worth his salt will always align the major loads with the rolling (L) direction, and fatigue cracks will grow perpendicular to the major loads, so they will NOT grow along grain boundaries, they will grow perpendicular to the grain boundaries. In contrast, stress corrosion cracks grow along grain boundaries so they grow parallel to the rolling direction and will be parallel to the span direction.

Stress corrosion cracking require three things: (1) an extruded, forged or rolled alloy which is susceptible to grain boundary corrosion, (2) a corrosive environment (and this may be as mild as the presence of water and some ions) and more importantly the presence of a residual stress such as would result from inadequate shimming or poor fit-up combined with the use of fasteners.

I have seen some STUPID repairs for SCC. The standard issue engineer looks at the SRM and finds "a repair for cracks in this area" and implements that repair without taking due cognisance of the crack direction. Most SRM repairs ASSUME cracks are fatigue cracks. In one case the repair required numerous fasteners to be installed ahead of the crack to be repaired, and the repair did absolutely nothing to provide restraint of crack opening.

I have been involved in a number of repair scenarios for SCC using bonded composite patches and these have been very effective. I just hope that the Airbus solution does not involve punching hundreds of fasteners through the structure to relieve local stresses due to flight loads, because if it is SCC, such repairs will be totally ineffective.

Regards

Blakmax

[grounded27]

Turbine D,

What is important to understand is the significance of the assembly orientation and the possible stresses put on the rib feet that would not be realized in service

I suppose no one could pre conceive the results of in service stresses, and I suppose this is an expected factor ...To an extent. From the alloy's that were used to general design of the aircraft, much is new. It is certain that more problems will reveal themselves over time (it does happen with all aircraft), it is the structural ones like this that have potential to cost $$$$$ in loss of time in service.

I would be just as critical of Boeing's composite fuselage. We are engineering aircraft w/o set precedent. We are using process standards based on what we know, skating the razors edge of the unknown.

[Machaca]

the video clearly shows a vacuum bag and autoclave procedure

Yes, of an aluminum wing skin panel being shaped & treated post milling.

[Turbine D]

Hi no-hoper,

Thanks for the information and correction of the wing manufacturing video. I think you are correct relative to the panel being placed against the ribs, it would appear to be an underside of the wing panel.

blakmax,

What you are seeing wrapped in the plastic bag is the wing panel including the fixture it is resting on. The fixture defines the desired shape (contour) that will
be established by the "baking process". After removal from the autoclave the wing panel is removed from the fixture. The skin is not bonded to the ribs per-se, but bolted using fasteners. For the composite ribs, a special fastner or bolt was designed by Alcoa working with Airbus for fastening metal to composite, see a picture of it below which was contained in an magazine article about Alcoa.
http://i1166.photobucket.com/albums/q609/DaveK72/lockbolt.jpg

I am not sure the slabs or thick plates, from which the ribs are machined, are rolled at all. If they are not, the grains would have random orientations based upon the solidification pattern. Repair of the cracks, assuming they are readily assessable, might be acomplished by welding as the alloy, IMO, is weldable by TIG or Stir welding processes.

Machaca,

Thanks for all the information you have provided. Airbus' Charles Champion's remarks concerning the dispersion of cracking makes for an interesting search process I would think!

[ChristiaanJ]

"Australian Licensed Aircraft Engineers Association"

The usual problem in English.... confusing 'mechanics' and 'engineers'.

And confusing "association" and "union".

[Turbine D]

Some additional information from Airbus as reported by Flightglobal. :uhoh:

The airframer said the choice of alloy - designated 7449 - combined with a fastener interference-fitting process appeared to be generating the first type of crack in the feet. But a second type of crack - which EASA described as "more significant" - was also being created during the pull-down of wing skins, in the area of a butt-strap joint used between different lower skin panels.

In the region of rib 26 and stringer 21, larger-than-expected gaps - some 1.5-2mm rather than 0.5mm - between the sections involved in the pull-down had resulted in stresses being induced, leading eventually to cracking under the wear of normal airline operations.

Airbus executive vice-president for programmes Tom Williams said the interim fix being carried out on affected aircraft naturally relieved these stresses, and eliminated the problem.

"We have enough ribs and feet [to conduct the repairs]," he said. Williams added that a permanent solution would look at changing the alloy - although this would require thicker rib-feet and add some 89kg in weight - and amending the pull-down process.

[ChristiaanJ]

What's the worry?
Anybody ever seen toilet paper tear properly on the perforations?

More seriously, a question.
Are there any pictures (photos, drawings, diagrams) that could tell this ancient a bit more in detail where exactly the problem occurs?

[pattern_is_full]

If I'm reading and viewing all this right, the likely failure would be a wing skin panel tearing free from the ribs at the attachment point (the little dog-biscuit-shaped "feet"). Correct?

Which wouldn't be good (lot of noise, lot of drag, loss of a percentage of lift, possible jamming of loose panel in flight controls) - but is a lot different from the ribs or spars themselves departing the airframe (the wing "falling off").

[Turbine D]

ChristiaanJ,

The best photo of the ribs containing the wing brackets or wing rib feet is depicted in machaca's post #78 on page #3, first photo. The multiple rectangular things that stick upward out of each rib, each with four holes, are the feet. I assume the type 1 cracks come out of one or more of these holes in certain locations. The shape that connects these to the actual rib is where I think the more serious type 2 cracks developed. I guess the cracks are more random in nature that what I would have thought.

[Turbine D]

pattern_is_full,

You are correct, that is the way I would read it as well.

[grounded27]

Turbine D

I guess the cracks are more random in nature that what I would have thought.

Every landing is different. I was turned on by a a hard landing at Osh Kosh recorded below.

A380 Hard Landing at Oshkosh - YouTube

This shows the enormous wing flex during a hard landing with a walk through. Every landing is different as I would expect every crack to be (hard or not). Be it a hard landing or not, be it a large crack or not in these rib feet. Sideload/torque in a crosswind is probably a significant factor to add to the random nature.

[CliveL]

[quote]If I'm reading and viewing all this right, the likely failure would be a wing skin panel tearing free from the ribs at the attachment point (the little dog-biscuit-shaped "feet"). Correct? [unquote]

Don't think so. The likely failure would be that one bolt (out of over 100) would not be transmitting torsion from skin into that one rib. The ribs don't carry any bending loads, just torsion and curvature crushing loads between top and bottom skins.

[Bolty McBolt]

Airbus has traced the problem to the 7449 aluminium used in the wing ribs. 7449 is more sensitive to the way the parts are assembled on the wing. They ruled out flight loads or fatigue as causes.

My 2 cents.
The rib feet cracking is in both carbon and alloy ribs.
The cracking has been found across the fleet (all airlines)
Some cracking has been found on wings not yet fitted.
The root cause seems to be in manufacture.
The fit of the fastener (similar to pictured in Turbine D post) has to much negative tolerance in the fit and therefore induces the cracks some of which can be seen by the naked eye others are found by NDI.
The inspection /repair sched is for the C2 check which will probably add many extra days to the ground time

This info is not knew and I am suprised it has taken this long to hit the prune :ok:

[TZ350]

According to this ;

;aluMATTER*|*Aluminium*|*Wrought Aluminium Alloys*|*Examples of Applications (http://aluminium.matter.org.uk/content/html/eng/default.asp?catid=214&pageid=2144417055)

7449 is a wrought alloy.

Reading the assembly description, it seems that this is a new process ;
Higher Levels of Automation Lift Productivity for Airbus A380 Wing Assembly Process (http://www.ien.com/article/higher-levels-automation/13788)

" For the Airbus A380 panel-production facility, Electroimpact built four machine lines, each with two machines for upper and lower surface panels. Each line includes three fixtures, where four panels are loaded. The jigs hold the components in accurate form and location while the automated machines drill, rivet, and bolt the components together. Sealant is applied to the components during the jig load. No temporary fasteners are used.
Thus, after fastening, the wing panel assemblies are complete. No interim operations are needed to clean and deburr. The one-up assembly process reduces handling damage and positioning inaccuracies (datum errors). The machines can install rivets and bolts in diameters of ¼ to ½ in., with a stack range up to 2.5 in. Automated cold working, hole probing, countersink sealing, and collar installation are all included. "


[quote]
" In the region of rib 26 and stringer 21, larger-than-expected gaps - some 1.5-2mm rather than 0.5mm - between the sections involved in the pull-down had resulted in stresses being induced, leading eventually to cracking under the wear of normal airline operations. " [quote]

Are the hole tolerances such that with a 2.0 mm gap lateral forces from fastener misalignment could also be introduced ?

[no-hoper]

User airborne on aero.de - Luftfahrt-Nachrichten und -Community (http://www.aero.de/forum) found this link.Thanks !

http://www.doricassetfinance.com/pdf/aviation_industry/120124_doric_update_a380.pdf

[P6 Driver]

Apologies if posted elsewhere...

The BBC are reporting that the A380 fleet requires inspections...

BBC News - Airbus to inspect all A380 superjumbos for wing cracks (http://www.bbc.co.uk/news/business-16942361)

[zerotohero]

I hear that the EK boys on the A380 are all on standby from next month? any one out there any info on this?

I always said I was glad I fly Boeing as I used to be a car dealer and French cars were shockingly bad! seems the planes maybe going the same way :}

[TomU]

Isn't it rather a tenuous link between French cars and aircraft wings manufactured in Wales or Chester or Filton or wherever?

[Rocket2]

Funny how they've not picked up on the latest 787 problem -
Boeing Orders Checks of 787 Dreamliners on Fuselage Delamination - Businessweek (http://www.businessweek.com/news/2012-02-07/boeing-orders-checks-of-787-dreamliners-on-fuselage-delamination.html)

[gsky]

you are right about French cars...but Airbus is not French.
It is European !
and the wings are made in the UK.
and whilst I am not a lover of things"French", I think Boeing have just as many problems with new aircraft. .
Think B787!!
and compare delays/problems with A380
It just silly to blame the French.

[SLFguy]

"It just silly to blame the French."


You don't know how the internet works do you? :E

[J52]

Did someone not enter the right information into the stress analysis model? Very unusual to have any cracking so early in service life (anywhere!). I thought tombstone design went out with the DC10.

[Sunnyjohn]

From Flight Global:

The airframer said the choice of alloy - designated 7449 - combined with a fastener interference-fitting process appeared to be generating the first type of crack in the feet. But a second type of crack - which EASA described as "more significant" - was also being created during the pull-down of wing skins, in the area of a butt-strap joint used between different lower skin panels.

In the region of rib 26 and stringer 21, larger-than-expected gaps - some 1.5-2mm rather than 0.5mm - between the sections involved in the pull-down had resulted in stresses being induced, leading eventually to cracking under the wear of normal airline operations.

Looks like the method of assembly is actually causing the problems.

[Dave Barnshaw]

And the wings are made in the U.K.--Hmmmmmmmmm!.

[ironbutt57]

this on Reuters

Europe to extend Airbus A380 checks - sources
Wed, 08/02/2012 - 10:21
By Tim Hepher

KUALA LUMPUR (Reuters) - European air safety officials are preparing to extend checks for Airbus A380 wing cracks to the entire superjumbo fleet, sources close to the matter told Reuters on Wednesday.

The move to inspect all 68 A380s in service came as Qantas Airways grounded one of its planes, saying engineers had found 36 wing cracks after the aircraft encountered severe turbulence.

By signalling that the defects may be structural and widespread, the fleet-wide inspection order will refocus attention on flaws identified in flagship jets at both Airbus and Boeing . The aircraft makers maintain that their newest jets remain safe to fly after problems were caught at an early stage.

"This is an extension of a process already underway," said one of the people, who asked not to be named. "An effective repair has been identified."

Airbus, a unit of European Aeronautic Defence & Space Co. , declined to comment on the additional inspections. A spokesman for the European Aviation Safety Agency (EASA) was not immediately available.

The aviation watchdog last month ordered checks on one-third of the A380 fleet after cracks were found in a handful of the thousands of L-shaped brackets that fix each wing's exterior to its internal ribcage-like structure.

EASA has yet to set out a timetable for the new inspections, two aviation sources said. Planes will be checked as they cross wear-and-tear thresholds at which the tiny cracks become detectable.

Inspectors had initially focused on 20 aircraft operated by Singapore Airlines , Air France and Dubai's Emirates - which have logged the most A380 flights since the double-decker plane entered service four years ago.

(Reporting by Tim Hepher; writing by Laurence Frost; Editing by Geert De Clercq and Jane Merriman)

[chrisN]

French? British?


From Machaca’s post 78 referred to above, the machine that does the fixing appears to be made by: “ . . . Electroimpact Inc., Mukilteo, Wash., the prime contractor for wing-assembly automation tools.”


Now which country is that?


IMHO – the country is irrelevant. The problem will be resolved, as engineering issues are in well regulated companies, by the usual disciplines, not by racist or other xenophobic point scoring. Nor by unqualified SLF opining freely.


Chris N

[ABAT4t2]

The problem will be resolved, as engineering issues are in well regulated companies

Perhaps this thread has been hijacked, I don't know. What I do know however is regardless of whether this gets sorted now or not and I genuinely believe it will, that isn't actually the issue.

We should be asking what sort of regulatory oversight is in place thats first denies an issue, then stalls on the inspection process for the rest of the fleet and then finally admits to an issue that engineers had been stating was there from day one.

The time scale is unacceptable and so don't be surprised if conspiracy theorists start suggesting cover ups or inventing links between Airbus the european manufacturer and Easa the european regulator.

I personally see one issue here and only one. I can no longer distinguish between regulator and operator. To me they are one and the same. Thats dangerous in my view.

[lomapaseo]

We should be asking what sort of regulatory oversight is in place thats first denies an issue, then stalls on the inspection process for the rest of the fleet and then finally admits to an issue that engineers had been stating was there from day one.

The time scale is unacceptable and so don't be surprised if conspiracy theorists start suggesting cover ups or inventing links between Airbus the european manufacturer and Easa the european regulator.

I personally see one issue here and only one. I can no longer distinguish between regulator and operator. To me they are one and the same. Thats dangerous in my view.

The regulatory issue is called Continued Airworthiness and has its own part under the codes.

It presumes that some degradation may occur over the life of the fleet and that the type holder/operator must provide an analysis and a program to address the issue in a manner that minimizes (not eliminate) the risk over the time period that it is in operation.

If the risk is high (compared to all other risks) than the time period that it is allowed to exist will be short. The implication of this that a fleet is always under a degree of risk for all other problems (known and unknown) and that no single known problem du jour, should significantly contribute

My read of the current discussion on this problem is that it will not significantly contribute to overall risk in the near time-frame, but must be addressed before accumulating even more risk (wear out mode).

The type holder, has apparently proposed a corrective action and the regulator accepted this with the understanding that as new data is found the corrective action program will be updated.

It's a validated process and I really don't see how we on the outside can pick it apart without new data

[viribus unitis]

The type holder, has apparently proposed a corrective action and the regulator accepted this with the understanding that as new data is found the corrective action program will be updated.The extended EASA AD is published since 2012-02-08. AD No.: 2012-0026

New:
Applicability: Airbus A380-841, A380-842, and A380-861 aeroplanes, all serial numbers.

This AD ... extends the applicability to all aeroplane serial numbers and requires
accomplishment of High Frequency Eddy Current (HFEC) inspections of certain
wing rib feet and accomplishment of applicable corrective actions.

[Boentgru]

Automatic dihedral!

[JohnDixson]

A Norwegian friend sent this to me and I wondered if the forum experts in this area had seen it:

Airbus CEO says wing cracks show risk of technology leaps | Business & Technology | The Seattle Times (http://seattletimes.nwsource.com/html/businesstechnology/2018281663_airbuswings25.html)

Thanks,
John Dixson

[Lyman]

Looking beyond the courage of Ender's remarks, things look worse than thought. It can be said that the culture at Airbus has been less than forthcoming, so as well as refreshing, the comments speak to the gravity of the situation. For eighteen months, a/c will be completed with materials that will fail, and involve serious downtime and cost that is staggering in their repair. Meanwhile, a/c fly with fractured ribs, looking at several milions in repair sooner or later.

Boeing is not immune; the storied delays may in the long run be a saving grace. However, a giant leap into new and untested technology (tested in long term).

In the case of the three-eighty, an ironic failure, naturally in pursuit of profit. Eventually a/c will fly as anorexic hangar queens? Light, Strong.........and Durable?

[Retired Peener]

One correction to this post. Only the upper surface wing panels of the A380 are creep formed during the precipitation hardening heat treatment. The lower surface panels on the A380 (as well as A310, A319/20/21, A330 and A340) are shot peen formed. The failing brackets on the A380 attach the ribs to the lower peen formed panels. The photo in this post is, indeed, of an upper surface panel in the autoclave at Broughton, North Wales. I was in charge of the US owned factories in North Wales from 1982 till my retirement in 2005 where all the above named lower Airbus panels were shot peen formed and shot peend along with many other Airbus (and other manufacturers) parts. Shot peening is a specialist cold working surface process which increases resistance to fatigue failure and stress corossion cracking as well is being used to induce form or correct distortion by inducing beneficial residual stresses.

[scientifics]

Is this aircraft safe to fly? The traveling public are led to believe that lots of cracks have been found but it remains safe. Any air frame engineers care to elaborate?

[Lyman]

Retired Peener,

I remember a vid of the upper skin in its machining stage, it was air tabled and routed to thickness. For its profile dimension, the lack of a platten or solid table made it look iffy to get good tolerance over the entire (single!) sheet.

So when the TRENT holed it, I immediately thought, well, there goes the monolithic integrity, they'll patch it. Did they? or did they ship a single sheet of upper skin to Aus, and layer it on site?

Can I assume a rough similarity between shot peening the lower skins to what a Jag scholar or Ferrari assembler would use an English Wheel? (beneficial residual stresses?)