cubastar
Topic Author
Posts: 312
Joined: Wed Nov 15, 2006 11:48 pm

Airbus VP -Will Need Years For A380 Wing Cracks

Mon Mar 19, 2012 10:27 pm

Quoted on Reuters - Airbus Vice President of Programs says it will take years to get past problems of "Wing Cracks" on the A380.

Brief Article here:
http://www.reuters.com/article/2012/...+News%29&utm_content=Google+Reader

Who is this individual Tom Williams? Does anyone have better information on this?
 
B6JFKH81
Posts: 1970
Joined: Thu Mar 16, 2006 6:35 am

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Mon Mar 19, 2012 10:32 pm

Quoting cubastar (Thread starter):
Who is this individual Tom Williams? Does anyone have better information on this?

His Bio is on the Airbus website:

http://www.airbus.com/company/people...ecutive-vice-president-programmes/
"If you do not learn from history, you are doomed to repeat it"
 
roseflyer
Posts: 9606
Joined: Fri Feb 13, 2004 9:34 am

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Mon Mar 19, 2012 10:33 pm

Years makes sense. Nothing is quick when making design changes. A year is about the minimum a simple change can get done in, so a change that requires both manufacturing process change and revised stress analysis is something that would take multiple years to fully incorporate and get retrofitted into the fleet.

No airplane is immune from this type of problem. That's why there are Service Bulletins in the first place. When such problems can be found is what makes the solution much different. If such problems are found after type certification, there usually is a window that they can get incorporated in using established. If it is prior to type certification then it can cause massive delays and hold up the program.

Quoting cubastar (Thread starter):

Who is this individual Tom Williams?

It looks like an executive in Engineering which is in my opinion is far better than seeing a quote from John Leahy who is in sales.
If you have never designed an airplane part before, let the real designers do the work!
 
something
Posts: 1239
Joined: Fri May 13, 2011 5:29 pm

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Mon Mar 19, 2012 11:05 pm

Quoting Roseflyer (Reply 2):
a change that requires both manufacturing process change and revised stress analysis

The problem is certification. Getting the new parts certified takes a long time, so that current productions are still delivered with the faulty parts. Eradicating the problem will take years because younger aircraft won't be pulled from service for the repair, but will have these parts changed during their first scheduled maintenance visit after 1500 cycles.
..sick of it. -K. Pilkington.
 
windshear
Posts: 2261
Joined: Tue Mar 14, 2000 4:45 pm

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Tue Mar 20, 2012 10:24 am

I am scheduled to fly on an A380 in April(be'ezrat hashem)... And this is concerning me a bit.

I know it's safe etc. but 2000 bolts with cracks... And the forces on those wings... Sounds scary to me.

Boaz
"If you believe breaking is possible, believe in fixing also"-Rebbe Nachman
 
Farzan
Posts: 72
Joined: Thu Jul 12, 2007 9:55 pm

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Tue Mar 20, 2012 10:32 am

Quoting Roseflyer (Reply 2):
Years makes sense. Nothing is quick when making design changes. A year is about the minimum a simple change can get done in, so a change that requires both manufacturing process change and revised stress analysis is something that would take multiple years to fully incorporate and get retrofitted into the fleet.

No airplane is immune from this type of problem. That's why there are Service Bulletins in the first place. When such problems can be found is what makes the solution much different. If such problems are found after type certification, there usually is a window that they can get incorporated in using established. If it is prior to type certification then it can cause massive delays and hold up the program.

As much as I love the A380, should I be worried about flying the plane? Obviously the plane is not grounded and production and deliveries are ongoing without (any further) delays? As such I assume that the "fix" is already established and can be carried out during normal maintenance.

Or?
 
Daysleeper
Posts: 565
Joined: Sun Dec 20, 2009 3:33 pm

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Tue Mar 20, 2012 11:48 am

Quoting farzan (Reply 5):
As much as I love the A380, should I be worried about flying the plane?

Is anyone able to find the article they are reporting about? Would be interesting to see the context of his comments.

In regards to it being safe to operate, I was under the impression that some operators had already pulled effected aircraft from the fleet and applied fixes. In fact there were several hysterical posts on here about the A380 being grounded for repairs to be undertaken (It was found to be a little awquad to do at 40,000 feet) and I’m sure that all of them will have been inspected by now.

So no, you have absolutely nothing at all to worry about, it’s as safe as any other modern aircraft flying today.

[Edited 2012-03-20 04:49:24]
 
User avatar
kc135topboom
Posts: 11007
Joined: Sun Jan 30, 2005 2:26 am

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Tue Mar 20, 2012 12:50 pm

Quoting windshear (Reply 4):
I am scheduled to fly on an A380 in April(be'ezrat hashem)... And this is concerning me a bit.

I know it's safe etc. but 2000 bolts with cracks... And the forces on those wings... Sounds scary to me.
Quoting farzan (Reply 5):
As much as I love the A380, should I be worried about flying the plane?

No, you should not be worried. Even I, who clearly is not an Airbus fan, nor a fan of the WhaleJet do not believe this is as huge a safety issue as some think it is. Airbus has to wait until the new designed clips are approved and production can be ramped up. In the meantime broken and cracked clips can be replaced with the current design clips, even though the airlines expect these replacements to eventually crack and break. The airlines can also fly the airplane at reduced "G" to relieve some of the stress on the wings. As long as the spars stay intact, the wing will not break. The worse that I see that can happen is the skin seperates from the ribs inflight, and then ripples. Then that section of skin has to be replaced, but flying it in a reduced "G" will reduce the chances of this happening.

All airplanes are designed to survive and fly with a certain degree of damage, I believe the A-380 clip problem is one of these events, just as the tail delamination problem on the B-787 is.
 
a380900
Posts: 801
Joined: Fri Dec 05, 2003 11:26 pm

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Tue Mar 20, 2012 12:59 pm

Well, this could very well postponed any A380-900 version of the plane. The A380 team will have their hands full for a while...
 
traindoc
Posts: 274
Joined: Thu Mar 06, 2008 11:35 am

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Tue Mar 20, 2012 2:09 pm

As this is the largest pax aircraft now in production, is this a factor? Clearly, when planes get bigger and heavier, physical stresses also increase. And these stresses are magnified by such things as wing length and flex.

On the other hand, the A380 is quite a strong airframe. Look how well the QF bird survived the significant damage from the unconfined engine failure!
 
User avatar
Stitch
Posts: 23214
Joined: Wed Jul 06, 2005 4:26 am

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Tue Mar 20, 2012 2:17 pm

Sounds all perfectly normal to me and while I admit to never giving thought to when I board a plane that I might not disembark, this cracking issue does not give me any pause about flying the A380.
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Tue Mar 20, 2012 2:21 pm

Quoting traindoc (Reply 9):
As this is the largest pax aircraft now in production, is this a factor? Clearly, when planes get bigger and heavier, physical stresses also increase

Unless the manufacturers screw up, or they change materials, the stresses shouldn't increase. The *forces* increase and you increase the size of the parts to keep the stress the same. The allowable stress for, say, 7075 aluminum doesn't change just because it's installed on a bigger airplane.

Tom.
 
User avatar
kanban
Posts: 3647
Joined: Sun Jan 06, 2008 1:00 am

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Tue Mar 20, 2012 4:04 pm

My suspicion is that although Airbus press releases reflect this is not a big concern as far as flight safety and remove and replace at the operators can happen during normal maintenance, I suspect the behind the scenes they will push airlines for rapid repair just to get the problem and press behind them.
 
roseflyer
Posts: 9606
Joined: Fri Feb 13, 2004 9:34 am

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Tue Mar 20, 2012 4:18 pm

Quoting kanban (Reply 12):
My suspicion is that although Airbus press releases reflect this is not a big concern as far as flight safety and remove and replace at the operators can happen during normal maintenance, I suspect the behind the scenes they will push airlines for rapid repair just to get the problem and press behind them.

Airbus really doesn't have that ability. They come up with the requirements for repair and create a Service Bulletin. The regulatory agencies decide/approve the interval that parts must be repaired/replaced in. The airlines are then required to follow the Service Bulletin by an Airworthiness Directive. As soon as the Service Bulletin and Airworthiness Directive is issued, Airbus has little to say and do with the fix. It is up to the airlines and their own regulatory authorities.

Quoting farzan (Reply 5):

As much as I love the A380, should I be worried about flying the plane? Obviously the plane is not grounded and production and deliveries are ongoing without (any further) delays? As such I assume that the "fix" is already established and can be carried out during normal maintenance.

People far more knowledgeable on the problem than anyone posting on the internet made the decision on if the airplanes are safe or not. It's the same people that designed the parts that are responsible for deciding if they are safe or not. Cracks are allowed in parts as they are always present. How big cracks can get is a determination made by engineering and stress analysts. If they say they are ok, then you are good to go and since the airplanes have not been grounded, you can feel confident that they are safe. If you don't trust them to decide if cracks are acceptable or not, you wouldn't trust them if the airplane was safe to begin with and probably never fly.
If you have never designed an airplane part before, let the real designers do the work!
 
User avatar
kanban
Posts: 3647
Joined: Sun Jan 06, 2008 1:00 am

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Tue Mar 20, 2012 6:23 pm

Quoting Roseflyer (Reply 13):
Airbus really doesn't have that ability.


While in principal I agree with you, I have known the other manufacturer to add incentives for rapid incorporation like paying for the downtime and labor. Service bulletins are quietly reviewed for public relations impact and based on the comments about flying on these planes the problem (real or imagined) is a PR problem.
Regulatory just says must be done by "x" flight hours, landings, etc. They don't say it can not be done sooner. Charge/no charge, implementation cost compensation are all the manufacturers call not regulator.
 
Cactus1549
Posts: 9
Joined: Tue Jun 15, 2010 9:15 am

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Tue Mar 20, 2012 7:22 pm

The A380 is safe despite of these ribs cracks. Today there's only a follow up on the fleet in service but no retrofit yet. Airbus has started shortly after the EASA's request to check the aircrafts in FAL1 and to think about the english manufacturing process. From next April, the A380 wings manufacturing process will change a little bit to avoid stress in the first building steps. It could be the solution. Let's see.
 
User avatar
kc135topboom
Posts: 11007
Joined: Sun Jan 30, 2005 2:26 am

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Tue Mar 20, 2012 9:26 pm

Quoting traindoc (Reply 9):
Look how well the QF bird survived the significant damage from the unconfined engine failure!

That event had notihing to do with the current foot cracking problem. The A-380 should be able to adsorb the type of damage the QF airplane had.

Quoting Cactus1549 (Reply 15):
Airbus has started shortly after the EASA's request to check the aircrafts in FAL1 and to think about the english manufacturing process. From next April, the A380 wings manufacturing process will change a little bit to avoid stress in the first building steps. It could be the solution. Let's see.

I doubt this problem is a manufacturing problem. It is a design failure or a material selection failure. Blaming the British for this is only going to cause political problems for Airbus as well as the EU.
 
rcair1
Crew
Posts: 1139
Joined: Wed Oct 28, 2009 8:39 pm

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Wed Mar 21, 2012 1:49 pm

While I agree that this issue is a non-issue for the 380, I would point out that there have been plenty if cases where cracks did cause major flight issues in recent years - from depressurization to wings falling off. True, nothing on aircraft as new as the 380, but I'm not sure that is an affirmative statement. I find it interesting that it would not have been found so early if it wasn't for NB.

Quoting Roseflyer (Reply 13):
People far more knowledgeable on the problem than anyone posting on the internet made the decision on if the airplanes are safe or not.

You have a 'rosier' view than I do. History is rife with people in the know being ignored by people in the $'s.
rcair1
 
User avatar
kanban
Posts: 3647
Joined: Sun Jan 06, 2008 1:00 am

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Wed Mar 21, 2012 3:28 pm

Quoting KC135TopBoom (Reply 16):
I doubt this problem is a manufacturing problem. It is a design failure or a material selection failure.


Awhile ago there was a video of the A380 wing being assembled up to the point of some secret process that they didn't want filmed. One of the things I noticed was the wrapping of the skin to the inspar ribs with what appeared to be hydraulic jacks. So far so good. Th next step was the attachment which wasn't shown. this where a process failure could occur leading to unusual stresses on a series of brackets. If the fastening process didn't pick up enough brackets to carry the load before moving to the next rib there could be problems.. kind of like the stagger tightening of engine heads bolts. If this was the cause, it's easily rectified.
 
roseflyer
Posts: 9606
Joined: Fri Feb 13, 2004 9:34 am

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Wed Mar 21, 2012 8:54 pm

Quoting rcair1 (Reply 17):

You have a 'rosier' view than I do. History is rife with people in the know being ignored by people in the $'s.

In a high profile case where cracks have been found, I don't think anyone would be able to pull off something like that. It used to be that the only regulatory agency was the FAA and Boeing, Douglas and Lockheed could pull some strings. Nowadays, there are there formidable regulatory agencies; FAA, EASA and Transport Canada. Airbus is far too ethical of a company with too much at risk to try falsifying stress analysis to indicate the cracks are acceptable when in fact they engineering doesn't back it up.

Quoting rcair1 (Reply 17):
While I agree that this issue is a non-issue for the 380, I would point out that there have been plenty if cases where cracks did cause major flight issues in recent years - from depressurization to wings falling off. True, nothing on aircraft as new as the 380, but I'm not sure that is an affirmative statement. I find it interesting that it would not have been found so early if it wasn't for NB.

In almost all cases, dramatic failures like that are for where cracks haven't been analyzed and they were missed. Rarely does the engineering come out incorrect when engineering says the crack is acceptable when it is not. Usually it is the case of never knowing about the crack or not thinking it was possible and then it happening. The only example that I can think of where engineering incorrectly responded to a design was the JAL 747 crash due to a faulty repair on the aft pressure dome.

In aviation it is almost never the problems that you do know about that bring down a plane. It is the problems and circumstances that no one thought of as possible that resulted in unpredicted failures.
If you have never designed an airplane part before, let the real designers do the work!
 
User avatar
bikerthai
Posts: 2176
Joined: Wed Apr 28, 2010 1:45 pm

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Wed Mar 21, 2012 9:58 pm

Quoting KC135TopBoom (Reply 7):

No, you should not be worried. Even I, who clearly is not an Airbus fan, nor a fan of the WhaleJet do not believe this is as huge a safety issue as some think it is.

I bet in your days you flew on may airplanes that have cracks on them. I have seen a 707 wheel well with with large cracks and stop drill holes in them. I bet they existed on the KC-135 also.  
Quoting rcair1 (Reply 17):
While I agree that this issue is a non-issue for the 380, I would point out that there have been plenty if cases where cracks did cause major flight issues in recent years

I would also bet that the cracks that caused the problems are the un-known cracks. At least for the A380, these cracks are known.

So to allay or perhaps increase the thread starter's fears. Cracks on airplanes are not exclusive to the A380. In fact, you may have already flown on aircraft with cracks on them. You just have to trust the airline, and the regulatory agency to address these crack is the proper manner to provide safe air travel, no matter which aircraft you fly.

bt
Intelligent seeks knowledge. Enlightened seeks wisdom.
 
Unflug
Posts: 698
Joined: Wed Jan 11, 2012 5:25 pm

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Thu Mar 22, 2012 10:00 am

Quoting cubastar (Thread starter):
Airbus Vice President of Programs says it will take years to get past problems of "Wing Cracks" on the A380.

The bad news is that it will take years. The good news in the same message is that we are talking about a problem not needing an immediate fix: they obviously can take quite a lot of time to fix it.
 
rcair1
Crew
Posts: 1139
Joined: Wed Oct 28, 2009 8:39 pm

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Thu Mar 22, 2012 1:23 pm

Quoting Roseflyer (Reply 19):
In almost all cases, dramatic failures like that are for where cracks haven't been analyzed and they were missed. Rarely does the engineering come out incorrect when engineering says the crack is acceptable when it is not. Usually it is the case of never knowing about the crack or not thinking it was possible and then it happening.

Yes - and luckily, an unlucky incident lead to finding these cracks which were not expected and had been missed so far. But - let's see, before that incident, the cracks had not been found (missed) and had not been analyzed. No do I think the fine AB engineers expected them (did not think it was possible, as they would surely not have designed it that way if they did). So I don't really understand the point of your post in relation to mine. All I said was that cracks, undiscovered in some cases, ignored in others, have caused problems. In this case the cracks were discovered long before they became an issue and are being managed. That is a good thing, not a bad one.

However, blanket statements that cracks in airliners are not a problem is not valid. I see more of that here than I like.

Quoting bikerthai (Reply 20):
I would also bet that the cracks that caused the problems are the un-known cracks. At least for the A380, these cracks are known.

In many of the cases, the cracks were known, or at least there were indicators for them that were ignored. In the Chalk Airlines crash there were many indications (repeated fuel leaks) of a problem. I agree that it is good that the cracks in the A380 were discovered long before they were an issue and this allows AB to address them very nicely. Nor, as an engineer who has done both design and manufacturing, am I surprised that a manf process could operate in such a way that a design the engineers think is fine, turned out to have a problem. It has happened to me. I've been standing on the production line, watching production while trying to find the source of a problem we were having and seeing a production working do something that was perfectly reasonable, but not what I had envisioned, and went 'duh, - that's it.'.

BTW - despite some AB-fan's apparent assumption - my comment is not an indictment of AB.. or Boeing, MD, Lockheed ... ah.. you fill in the blank.
rcair1
 
User avatar
bikerthai
Posts: 2176
Joined: Wed Apr 28, 2010 1:45 pm

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Thu Mar 22, 2012 1:52 pm

Quoting rcair1 (Reply 22):

In many of the cases, the cracks were known, or at least there were indicators for them that were ignored.

Yeah, it is confusing to the general public when we talk about acceptable and non acceptable cracks.

I guess that is why if you are concern about flying, then select an airline that have a track record of not ignoring these cracks.

bt
Intelligent seeks knowledge. Enlightened seeks wisdom.
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Thu Mar 22, 2012 1:59 pm

Quoting rcair1 (Reply 22):
But - let's see, before that incident, the cracks had not been found (missed) and had not been analyzed.

There was no requirement to inspect them before that incident so the fact that they hadn't been found didn't mean they'd been missed.

They definitely would have been analyzed; the A380 (like every airliner since about the 757) is a damage tolerant design. You analyze it assuming there is a crack present, whether there is one or not.

Quoting rcair1 (Reply 22):
No do I think the fine AB engineers expected them (did not think it was possible, as they would surely not have designed it that way if they did).

They absolutely did think it was possible and absolutely did design it to handle a crack. What went wrong, here, is that the expected stress was off from the actual stress so the expected crack growth rate was *way* off (crack growth is extremely non-linear with applied stress). As a result, the inspection interval was too long and the cracks got a lot bigger than the AB engineers expected in the given time.

Quoting rcair1 (Reply 22):
All I said was that cracks, undiscovered in some cases, ignored in others, have caused problems.

Which is why airliners are damage tolerant designs, rather than safe-life or fail-safe now. Not saying cracks aren't a problem, they are, but they're handled *very* differently today than they were on aircraft like the original 737 with the Aloha Airlines event.

Tom.
 
windshear
Posts: 2261
Joined: Tue Mar 14, 2000 4:45 pm

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Fri Mar 23, 2012 9:33 am

It seems to be getting worse...

http://www.flightglobal.com/news/art...pe-two-cracks-on-two-a380s-369868/

I am beginning to think that the A380 I am scheduled to fly on, will end up being a 747.

Boaz.
"If you believe breaking is possible, believe in fixing also"-Rebbe Nachman
 
abba
Posts: 1382
Joined: Mon Jun 06, 2005 12:08 pm

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Fri Mar 23, 2012 12:26 pm

Quoting windshear (Reply 25):
It seems to be getting worse...



??? I think that it has been known for quite some time that there were two types of cracks. See e.g. (dated Jan. 20) http://www.flightglobal.com/news/art...k-20-a380s-for-wing-cracks-367175/

I even remember that someone at some point posted photos of the two different types of cracks. It explained quite well what the different types were all about. I can't find them, however. What the article you are linking to says is simply that Qantas has found a few more type two cracks on some of its frames. I think that is what should be expected.
 
User avatar
bikerthai
Posts: 2176
Joined: Wed Apr 28, 2010 1:45 pm

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Fri Mar 23, 2012 1:13 pm

Quoting abba (Reply 26):
Quoting windshear (Reply 25):
It seems to be getting worse...



??? I think that it has been known for quite some time that there were two types of cracks.

True, but I think what is getting worse is the estimated cost of performing all the repairs. At the beginning of the crack discovery, I was wondering how much it will cost Airbus. Now I will be wondering how much it will increase the next time they revise the cost estimate.


bt
Intelligent seeks knowledge. Enlightened seeks wisdom.
 
User avatar
Revelation
Posts: 14025
Joined: Wed Feb 09, 2005 9:37 pm

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Fri Mar 23, 2012 1:40 pm

Quoting Roseflyer (Reply 19):
The only example that I can think of where engineering incorrectly responded to a design was the JAL 747 crash due to a faulty repair on the aft pressure dome.

To split hairs a bit, the correct repair was developed, but the person doing the repair didn't do the specified work. They used one doubler instead of the two that were specified.

Quoting tdscanuck (Reply 24):
They absolutely did think it was possible and absolutely did design it to handle a crack. What went wrong, here, is that the expected stress was off from the actual stress so the expected crack growth rate was *way* off (crack growth is extremely non-linear with applied stress). As a result, the inspection interval was too long and the cracks got a lot bigger than the AB engineers expected in the given time.
Quoting tdscanuck (Reply 24):
Which is why airliners are damage tolerant designs, rather than safe-life or fail-safe now. Not saying cracks aren't a problem, they are, but they're handled *very* differently today than they were on aircraft like the original 737 with the Aloha Airlines event.

Thanks again for your insight on how these things are actually handled. It should not amaze me the degree to which these things are understood, but it still does!
Inspiration, move me brightly! Light the song with sense and color.
Hold away despair, more than this I will not ask.
Faced with mysteries dark and vast, statements just seem vain at last.
Some rise, some fall, some climb, to get to Terrapin!
 
User avatar
kc135topboom
Posts: 11007
Joined: Sun Jan 30, 2005 2:26 am

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Fri Mar 23, 2012 2:20 pm

Quoting kanban (Reply 18):
Quoting KC135TopBoom (Reply 16):I doubt this problem is a manufacturing problem. It is a design failure or a material selection failure.

Awhile ago there was a video of the A380 wing being assembled up to the point of some secret process that they didn't want filmed. One of the things I noticed was the wrapping of the skin to the inspar ribs with what appeared to be hydraulic jacks. So far so good. Th next step was the attachment which wasn't shown. this where a process failure could occur leading to unusual stresses on a series of brackets. If the fastening process didn't pick up enough brackets to carry the load before moving to the next rib there could be problems.. kind of like the stagger tightening of engine heads bolts. If this was the cause, it's easily rectified.

I saw that video, too. You could be right about the tourque seqence being part of the problem. But the sequence would be designed by engineers, so the process they direct in manufacturing is still a design and not a manufacturing problem.

Quoting Roseflyer (Reply 19):
Quoting rcair1 (Reply 17):
You have a 'rosier' view than I do. History is rife with people in the know being ignored by people in the $'s.
In a high profile case where cracks have been found, I don't think anyone would be able to pull off something like that. It used to be that the only regulatory agency was the FAA and Boeing, Douglas and Lockheed could pull some strings. Nowadays, there are there formidable regulatory agencies; FAA, EASA and Transport Canada. Airbus is far too ethical of a company with too much at risk to try falsifying stress analysis to indicate the cracks are acceptable when in fact they engineering doesn't back it up.

This could go back to the fact the wing break test was never reaccomplished after the initial wing broke at only 147%, IIRC. Airbus did some redesign work and then conducted the break test using a computer simulation to get to the required 150%, a procedure the EASA approved at the time. The wing break tests are designed to put 150% of the maximum expected load on a completed wing, including all internal and external parts, except for slats, flaps, spoilers, wingtips, and other non-load bering parts. So the rib-feet attachments would have been installed within the test wing. Usually this test wing is scrapped soon after the test is completed. But detailed photos, as well as the collected computer data, of all the parts, cracks and break point should still be around. I am wondering if those pictures and data have been revisited?

In any case, even if the stresses placed on the rib-feet were not reveiled in the wing break test, these parts are failing at a point well below the 150% load stress point, and most likely closer to the 100% load stress point.

This is not to say the wing will suddenly fall off inflight, it will not do that as the spars are the main component and strenght of the wing, and the ribs essentially hold the spars inplace within the wing. My guess is the worst that can happen is the lower skin will seperate from the ribs and most likely cause a fuel leak, of some unknown size as that depends on what the airplane was doing when the feet fail and how many feet fail to hold the skin in place. I suspect it would look something like that USAF E-8C (B-707) that had a main wing fuel tank failure inflight last year (the fuel tank plugs were not removed after maintenance), but still was able to land safely, although that airplane is now being scrapped as the internal wing damage was extensive. There were pictures of the internal wing damage on the military boards here on a.net.

Quoting bikerthai (Reply 20):
Quoting KC135TopBoom (Reply 7):
No, you should not be worried. Even I, who clearly is not an Airbus fan, nor a fan of the WhaleJet do not believe this is as huge a safety issue as some think it is.
I bet in your days you flew on may airplanes that have cracks on them. I have seen a 707 wheel well with with large cracks and stop drill holes in them. I bet they existed on the KC-135 also.

Correct. We did have cracks. In fact the entire lower wing skin had to be changed from just outboard on the #1 engine to just outboard of the #4 engine on every KC/EC/RC/C/WC/VC-135. The process began reskinning the under wing surfaces in 1975, I think, and it took until about 1989 to complete all of the -135s.

Quoting windshear (Reply 25):
I am beginning to think that the A380 I am scheduled to fly on, will end up being a 747.

There are worse things in life than that. Personally, I would prefer the B-747 over the A-380 anyway, and not because of the rib-feet problems. I just like Boeing airplanes.
 
User avatar
kanban
Posts: 3647
Joined: Sun Jan 06, 2008 1:00 am

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Fri Mar 23, 2012 4:36 pm

Quoting KC135TopBoom (Reply 29):
. But the sequence would be designed by engineers, so the process they direct in manufacturing is still a design and not a manufacturing problem.


I concur, and thinking about the disjointed engineering presence at AB, I would suspect that the tool design engineers didn't think about it, the wing structure engineers didn't review the tooling design in detail, and the manufacturing engineers only referred to the tooling load document. (have seen this happen at Boeing when all the players were scattered over Puget Sound). They also may have thought the hydraulic rams holding the skin in place were sufficient to preclude developing a riveting pattern.

The thing I have not seen that would shed light is a scatter diagram showing which flanges are cracking from stress and overlaid with the tooling support shadows.

The other failure they indicated was a improper fastener installation causing a different type of stress cracking.. this may be do to tool interference.. but we will probably never know.
 
milesrich
Posts: 1508
Joined: Sun Jul 06, 2003 2:46 am

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Fri Mar 23, 2012 5:22 pm

Quoting windshear (Reply 4):
Quoting windshear (Reply 4):

I am scheduled to fly on an A380 in April(be'ezrat hashem)... And this is concerning me a bit.

I know it's safe etc. but 2000 bolts with cracks... And the forces on those wings... Sounds scary to me.

You will land safely, be'esrat hashem. It's beshert! Enjoy your Pesach!
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Sat Mar 24, 2012 6:11 pm

Quoting Revelation (Reply 28):
It should not amaze me the degree to which these things are understood, but it still does!

The structural guys still get surprised...every time they change design philosophies the one they change to is the "be-all-and-end-all"...until they find out there's some uncovered assumption.

Fail-safe was widely assumed to work great until the horizontal tail came off a Dan Air 707 where the primary and fail-safe chords cracked through.

Safe-life was widely assumed to work great until the center wing box of an F-111 came apart due to an undetectable manufacturing defect.

Damage tolerant (where most aircraft live today) simply assumes that you've got undetected cracks everywhere and, you'd think, would over all situations. Then the top came off the Aloha 737 and they had to modify damage tolerant to include multi-site damage.

It's a continual learning process but, as you note, it's a lot better understood and designed for than it probably looks like to the flying public.

Quoting KC135TopBoom (Reply 29):
This could go back to the fact the wing break test was never reaccomplished after the initial wing broke at only 147%, IIRC.

This is a fatigue problem; it shouldn't show up on the static test aircraft. I would assume Airbus is all over their fatigue test frame with a fine tooth comb though.

Tom.
 
bmacleod
Posts: 2546
Joined: Sat Aug 25, 2001 3:10 am

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Sat Mar 24, 2012 6:25 pm

This is a minor issue right? I mean it won't result in the A380 being grounded for wing repairs?
"What good are wings without the courage to fly?" - Atticus
 
User avatar
Revelation
Posts: 14025
Joined: Wed Feb 09, 2005 9:37 pm

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Sat Mar 24, 2012 8:45 pm

Quoting bmacleod (Reply 33):
I mean it won't result in the A380 being grounded for wing repairs?

Correct. The current state of affairs is that inspections are being made and repairs are being scheduled but there is no known reason for a mass grounding of the A380 fleet, nor is that a likely outcome.

As Zeke said above, there are over 2000 of these parts in each A380, and only a small number of failures are being reported, and these failures don't compromise the short term integrity of the parts. In essence, it's more of a long term maintenance issue and the main issue is cost, not safety.
Inspiration, move me brightly! Light the song with sense and color.
Hold away despair, more than this I will not ask.
Faced with mysteries dark and vast, statements just seem vain at last.
Some rise, some fall, some climb, to get to Terrapin!
 
Ruscoe
Posts: 1577
Joined: Sun Aug 22, 1999 5:41 pm

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Sat Mar 24, 2012 9:34 pm

Quoting tdscanuck (Reply 32):
fatigue problem; it shouldn't show up on the static test aircraft. I would assume Airbus is all over their fatigue test frame with a fine tooth comb though.

A manufacturing fault may not show up on a fatigue test frame but surely a fatigue crack (type 2) should

Quoting Revelation (Reply 34):
As Zeke said above, there are over 2000 of these parts in each A380,

Surely there are not 2000 wing ribs, where the more important fatigue cracks are!


Ruscoe
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Sat Mar 24, 2012 10:34 pm

Quoting Ruscoe (Reply 35):
A manufacturing fault may not show up on a fatigue test frame but surely a fatigue crack (type 2) should

The fatigue crack is caused by the manufacturing fault. Unless the fatigue test frame was build differently, the crack will show up in the fatigue frame just as it does in the in-service aircraft.

The crack wasn't present at manufacture; that would be caught before wing was even completed. The assembly issue causes the stress to be higher in the wing rib feet than designed, so the existing cracks in the feet (all parts have existing cracks) are growing much faster than anticipated. They're becoming macroscopic way earlier than intended.

Quoting Ruscoe (Reply 35):
Surely there are not 2000 wing ribs, where the more important fatigue cracks are!

There are 2000 wing rib feet, which is where the cracks are.

Tom.
 
windshear
Posts: 2261
Joined: Tue Mar 14, 2000 4:45 pm

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Sat Mar 24, 2012 11:33 pm

Quoting milesrich (Reply 31):

תודה רבה!
וגם פסח שמח לך

Bezrath Hashem everything will be fine!
I have a crush on the 747, and I loved my flight from HKG to LHR last summer.
But it's a long flight from LHR to SYD so I am looking forward to a new aircraft and a spacious cabin  

Boaz
"If you believe breaking is possible, believe in fixing also"-Rebbe Nachman
 
NWAROOSTER
Posts: 1031
Joined: Mon Feb 14, 2005 2:29 pm

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Sun Mar 25, 2012 10:33 pm

There have been "engineering" design problems since the Wright brother first flew and new problems will continue to exist. The Comet had cracking problems around fuselage windows that caused several crashes. Both the Martin 202 and Lockheed L188 Electra had serious wing flaws that resulted in crashes. The Douglas DC-10 had design flaws that resulted in crashes. The catastrophic failure of the number two engine resulted in the rupture of the hydraulic system, due to failure of not installing hydraulic fuse plugs. This resulted in the controlled crash of a United DC-10 upon landing at Sioux City, Iowa. Only the skill of the flight crew allowed this to be a survivable crash. A Turkish DC-10 crashed in France due to the failure of a rear cargo door in flight.. A United Boeing 747 had to make an emergency landing at HNL due to forward cargo door separating from the aircraft in flight, with loss of some passengers. An Aloha 737 had to make an emergency landing in HNL when the upper fuselage separated in flight due to the failure of the cold bonded lap joints and and cracks developing around the rivets. One flight attendant was sucked out to her death. The, I think, all female flight crew made a successful emergency landing. Southwest Airlines, recently had a 737 in which the upper fuselage ruptured in flight. The aircraft landed successfully. These failures all occurred either due to engineering faults , maintenance deficiencies, or ground handling problems.
Then there was the American Airlines DC-10 that crashed in Chicago, Illinois. Due to improper procedures in changing the wing engine. The engine with the pylon separated from the aircraft on take off causing the failure of the hydraulic system and and cable system that controlled the leading edge flaps. This was attributed to maintenance employees using a fork lift to remove and install the wing engine with the pylon. This caused excessive lateral pressure on the mono ball assembly, which resulted in cracking of the mono ball ring assembly, thus allowing the engine to pull itself off the wing. This was both a maintenance failure and an engineering failure due to failure of the cable system.
Airbus is not immune to engineering and manufacture problems any more than the other manufactures. Aircraft now are built closer to minimums so as to reduce weight and fuel consumption. Therefore all manufactures are going to need to better engineer their aircraft and improve and control the manufacture of their aircraft. Operators will need to be more careful and vigilant in the maintenance and operation of their aircarft.   
Procrastination Is The Theft Of Time.......
 
Ruscoe
Posts: 1577
Joined: Sun Aug 22, 1999 5:41 pm

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Mon Mar 26, 2012 8:07 am

Quoting tdscanuck (Reply 36):
There are 2000 wing rib feet, which is where the cracks are.



I must be confused. So what's new.

I agree there are 2000 rib feet and these are where the manufacturing fault has resulted in what are cracks of a relatively minor type.

However as I understand it there are also horizontal cracks in the wing ribs themselves, which are fatigue related, not manufactureing related, and are more important than the wing rib feet cracks.

Ruscoe
 
User avatar
Revelation
Posts: 14025
Joined: Wed Feb 09, 2005 9:37 pm

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Mon Mar 26, 2012 10:27 am

Quoting Ruscoe (Reply 39):
I must be confused.
http://www.flightglobal.com/news/art...tress-a380-wing-components-367394/ makes it clear that some cracks are in the feet and others are in the ribs:

Quote:

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.

"It's not a materials quality issue. It's not a production issue. It's the combination of both," said Airbus.
Inspiration, move me brightly! Light the song with sense and color.
Hold away despair, more than this I will not ask.
Faced with mysteries dark and vast, statements just seem vain at last.
Some rise, some fall, some climb, to get to Terrapin!
 
Ruscoe
Posts: 1577
Joined: Sun Aug 22, 1999 5:41 pm

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Mon Mar 26, 2012 11:01 am

Quoting Revelation (Reply 40):
ading eventually to cracking under the wear of normal airline operations.

This indicates to me that it aldo a fatique related problem.

Ruscoe
 
User avatar
kc135topboom
Posts: 11007
Joined: Sun Jan 30, 2005 2:26 am

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Mon Mar 26, 2012 12:50 pm

Quoting Revelation (Reply 40):
"It's not a materials quality issue. It's not a production issue. It's the combination of both," said Airbus.

In other words, it is a design/engineering issue. The engineers select the material to be used on a part and design a method to install/assemble the part.
 
User avatar
Revelation
Posts: 14025
Joined: Wed Feb 09, 2005 9:37 pm

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Mon Mar 26, 2012 1:07 pm

Quoting Ruscoe (Reply 41):
This indicates to me that it aldo a fatique related problem.

Tom's reply in #36 explains it well. It takes some usage/fatigue to make the problem visible, but the manufacturing process triggers it by putting more stress than anticipated onto the parts, which makes them vulnerable to fatiguing.

It's kind of like the paper clip that works well in its intended use, but if you bend it back and forth a few times before using it, it's not going to be very good. In this case, it was the manufacturing process that did the equivalent of bending the clip back and forth a few times.
Inspiration, move me brightly! Light the song with sense and color.
Hold away despair, more than this I will not ask.
Faced with mysteries dark and vast, statements just seem vain at last.
Some rise, some fall, some climb, to get to Terrapin!
 
Daysleeper
Posts: 565
Joined: Sun Dec 20, 2009 3:33 pm

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Mon Mar 26, 2012 1:12 pm

Quoting Ruscoe (Reply 41):
This indicates to me that it aldo a fatique related problem.
Quoting KC135TopBoom (Reply 42):
In other words, it is a design/engineering issue

Where does it say it’s a design issue? The above quote says its related to the material and it’s installation process, which would be a manufacturing issue rather than a design issue.

In either case, it doesn’t appear to be that serious and the only real problem is the time out of service while the problem is addressed.
 
User avatar
zeke
Posts: 9944
Joined: Thu Dec 14, 2006 1:42 pm

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Mon Mar 26, 2012 1:40 pm

Quoting Ruscoe (Reply 39):
However as I understand it there are also horizontal cracks in the wing ribs themselves, which are fatigue related, not manufactureing related, and are more important than the wing rib feet cracks.

No the cracks are not in the ribs, half of the ribs on the A380 are made from Al, the other half are made from composite. All of them have Al rib feet, which are brackets of different shapes that join the ribs to the skin. This diagram shows the rib feet.



The two types of cracks are shown in these diagrams, the materials engineering mechanism that causes the type types of cracks is slightly different, hence te reason why the are propagating in different areas of the brackets. Both are caused by residual stresses during the assembly process.

The type1 crack are propagating from the fastener holes, the type 2 cracks are in the web of the bracket parallel to the wing skin.

Type 1



Type 2



What caused the residual stress during the production process is getting the very large wing skin panels to be hard up against the rib feet with no gap in 3 dimensions, and the use of interference fit fasteners. From what I understand all of the cracks are located mid span, I.e. the area around the centroid of the large wing panel.

I should add the Al-Zn alloy used in the rib feet has been used by Airbus for a long time on the A330/A340 wings, Boeing uses similar Al-Zn (7XXX) series alloy on the 777 wing and fuselage.

[Edited 2012-03-26 06:43:45]
We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
 
babybus
Posts: 2379
Joined: Sun Dec 28, 2003 5:07 am

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Mon Mar 26, 2012 3:18 pm

Maybe us Brits need to apologize for letting the Airbus side down, cracks in wings on the World's most prestigious aircraft and engines that blow up in flight. We are not doing very well really.

Since no aircraft authority has decided to order a grounding of A380s I guess we can rest assured that the plane is completely safe to fly. The 787 didn't sound too safe before it went into service but that problem seems to be have sorted itself out too.
and with that..cabin crew, seats for landing please.
 
roseflyer
Posts: 9606
Joined: Fri Feb 13, 2004 9:34 am

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Mon Mar 26, 2012 4:33 pm

Quoting Daysleeper (Reply 44):
Quoting Ruscoe (Reply 41):
This indicates to me that it aldo a fatique related problem.
Quoting KC135TopBoom (Reply 42):
In other words, it is a design/engineering issue

Where does it say it’s a design issue? The above quote says its related to the material and it’s installation process, which would be a manufacturing issue rather than a design issue.

Typically robust design can overcome manufacturing defects. Manufacturing cannot overcome design defects. Many times manufacturing problems are fixed with design changes.

In this case I have a feeling it is a design that did not have some factors built in to it for manufacturability. The term design defect has a very specific meaning as it relates to the warranty of the airplane. Any design defect resulting in repair or replacement costs to the airlines are typically covered under warranty.

In the first case it appears that the design resulted in a manufacturing process that had higher residual stresses in the parts. The choice of material combined with the manufacturing method resulted in cracks. That's a design/engineering problem and not a manufacturing problem when I read it.

The second problem appears to have a manufacturing process that results in residual stress. Changing the manufacturing process appears to relieve stress, so I'm not sure how to classify that problem, but I have a feeling that for warranty purposes it will be also a design defect.

Quoting Daysleeper (Reply 44):

In either case, it doesn’t appear to be that serious and the only real problem is the time out of service while the problem is addressed.

While not a safety problem, it will result in some pretty hefty warranty payments. It will be more than time out of service for inspections. It appears there will be a Service Bulletin(s) for repair which may be quite costly depending on what method is used. There's a lot more flexibility with airplanes that are already delivered than having to fix airplanes that haven't been delivered yet, but I would assume Airbus will be paying out of service costs as well as labor and repair costs.
If you have never designed an airplane part before, let the real designers do the work!
 
User avatar
kanban
Posts: 3647
Joined: Sun Jan 06, 2008 1:00 am

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Mon Mar 26, 2012 5:19 pm

Quoting babybus (Reply 46):
Maybe us Brits need to apologize for letting the Airbus side down,


Before you start self flagellating, were the feet designed and manufactured in Britain?
 
Daysleeper
Posts: 565
Joined: Sun Dec 20, 2009 3:33 pm

RE: Airbus VP -Will Need Years For A380 Wing Cracks

Mon Mar 26, 2012 6:43 pm

Quoting Roseflyer (Reply 47):
Typically robust design can overcome manufacturing defects. Manufacturing cannot overcome design defects. Many times manufacturing problems are fixed with design changes.

I don’t believe, or at least the last press release I read stated that Airbus is making changes to the manufacturing process – Not the design.

Quoting Roseflyer (Reply 47):
but I would assume Airbus will be paying out of service costs as well as labor and repair costs.

I agree it’s certainly going to cost them a lot of money, perhaps more now EK has agreed to pay compensation to passengers for the inferior inflight service when 777's had to substitue for the A380.