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.

pattern_is_full,

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

Turbine D

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


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.

[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.

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:

According to this ;

;aluMATTER*|*Aluminium*|*Wrought Aluminium Alloys*|*Examples of Applications

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

" 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 ?

User airborne on aero.de - Luftfahrt-Nachrichten und -Community found this link.Thanks !

http://www.doricassetfinance.com/pdf...pdate_a380.pdf

A380 Wing Cracks
 

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

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 :}

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

Funny how they've not picked up on the latest 787 problem -
Boeing Orders Checks of 787 Dreamliners on Fuselage Delamination - Businessweek

herotozero
 

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.

"It just silly to blame the French."


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

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.

From Flight Global:

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

A380 wing problems.
 

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

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)

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

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.

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