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  (Source: United Artists)
Latest issues come at an inopportune time for Airbus who is trying to fight off Boeing's superjet entrant

The Australian Licensed Aircraft Engineers Association (ALAEA) is sounding the alarm on one of the world's most iconic passenger aircraft designs, claiming that they are suffering from a design flaw.

The aircraft in question is the Airbus A380, the world's largest passenger jet.  The four-engine aircraft is manufactured by Airbus, a subsidiary of The European Aeronautic Defence and Space Company N.V. (EADS) (EPA:EAD).  

The airplane, which saw its maiden flight in April 2005, and saw an Oct. 2007 commercial introduction, has enjoyed having no real peer over the last several years, as it offers almost 50 percent more floor space than The Boeing Comp.'s (BA) 747-400.  It packs 478 square metres (5,145.1 sq ft) of floor space.  The A380-800 variant has a range of 15,400 kilometres (8,300 nmi; 9,600 mi) and has a cruising speed of Mach 0.85 (about 900 km/h or 560 mph at cruising altitude), meaning that it can travel from Hong Kong to New York City, without refueling, in only 17 hours.

But according to the Australian engineering group, the deployed aircraft show cracking in their wing ribs.  Steve Purvinas, secretary of the ALAEA, comments, "We can't continue to gamble with people's lives and allow those aircraft to fly around and hope that they make it until their four-yearly inspection."

The cracks were first found on A380s deployed in the fleets of Singapore Airlines (SGX: C6L) and Qantas Airways (ASX: QAN) (which primarily operates out of Australia).  The two airlines account 26 out of the 50 delivered passenger A380-800s, as the second and third largest A380 users.

A380 Plane
The Airbus A380-800 [Image Source: Qantas Airways]

So far no American airline company has adopted A380.  FedEx Corp. (FDX) and United Parcel Service, Inc. (UPS) placed commercial orders, but later cancelled after being inconvenienced by delays from the aircraft-maker.

BBC News quotes Airbus representatives as confirming the wing rib cracking, but insist it's harmless, and that passengers shouldn't be worried about the cracking wings.  States the company, "We confirm that minor cracks were found on some noncritical wing rib-skin attachments on a limited number of A380 aircraft. We have traced the origin. Airbus has developed an inspection and repair procedure, which will be done during regular, routine scheduled four-year maintenance checks. In the meantime, Airbus emphasizes that the safe operation of the A380 fleet is not affected."

Qantas has thus far repaired two of the members of its fleet that it spotted cracks in.

The A380 had been being considered as a possible upgrade option for the President of the United States' plane, Air Force One.  This is not the first issue to afflict the craft -- earlier wiring issues delayed shipments of the aircraft.

The cracking issues are bad timing for Airbus.  The company is currently trying to sell new customers on the aircraft and ward off Boeing, who just unveiled the Boeing 747-8 Intercontinental, a craft that finally brings Boeing abreast of Airbus in the mega-aircraft department.  The 747-8 took its maiden flight in Feb. 2010.

Source: BBC News



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RE: That's just great !
By Solandri on 1/9/2012 1:20:16 PM , Rating: 5
1) Cracking in aluminum structures is inevitable. Aluminum does not have a fatigue limit - there is no way to build with it in a manner which does not produce cracks that grow with use.
http://en.wikipedia.org/wiki/Fatigue_limit

This is why airframes are retired after a bit over 100,000 flights. You build them knowing that cracks will develop, and rely on design to mitigate the effects, and inspections to catch any cracks which grow faster than expected by the design. After a certain number of uses, you throw the whole thing away. The mere presence of cracks is not indicative of a problem.

2) This is not a primary load-bearing member. The purpose of the rib is give the skin of the wing its shape. A failure here would simply result in the skin of the wing flexing a little bit more. Any load being carried by the cracked section would be transferred over to other parts of the rib, or to adjacent ribs. The main load-bearing member of the wing is the spar, which runs lengthwise and connects the wing to the fuselage.


RE: That's just great !
By mcnabney on 1/9/2012 1:23:47 PM , Rating: 3
Yes, but isn't this a little early in their service life?


RE: That's just great !
By FITCamaro on 1/9/2012 1:28:27 PM , Rating: 2
Good post.


RE: That's just great !
By Keeir on 1/9/2012 2:01:20 PM , Rating: 6
A few points

1. Airframes currently do not have a mandated retirement limit. There are manufacturer's suggested lifespans. The FAA is working on a mandated retirement limit. The limit will be different for different airframes. For something as large as an A380, the limit would likely be 30,000-40,000 flight cycles. (Due to the large oval nature of the airframe, the stress caused by internal pressure will be high.)

2. The existence of cracking does not show a problem. The size of cracking in this case is suggesting a potential problem. Likely there is an installation issue, which is resulting in high local fatigue stresses/stress corrosion.

3. Errrr.... While something may not be a load bearing area, that doesn't mean it is not important. The aerodynamic surface of the wing is -very- important is several areas. For example, the leading edge. A panel failure of the leading edge can make certain maneuvers difficult/impossible. If the pilot is unaware of potential issues, he would be faced with a difficult situation where his instruments and computer are telling him there is a problem, but he has no real knowledge of his new limitations.

Potentially, if the A380 computer system is sensitive enough to detect changes in airflow over the wing and inform the pilot of their changed flight envelope, I can agree that this issue is relatively minor. But Civil Aviation Agencies typically don't talk out like this unless there is a relatively high danger.


RE: That's just great !
By bug77 on 1/9/2012 2:38:53 PM , Rating: 2
quote:
This is not a primary load-bearing member.


Then why did it crack first? Something doesn't feel right.


RE: That's just great !
By Keeir on 1/9/2012 3:58:35 PM , Rating: 5
quote:
Then why did it crack first? Something doesn't feel right.


When building something like an airplane that is very weight critical, there is often very little tolerance for mistakes in installation. For example, an unshimmed gap of just 0.050" between two parts can lead to cracking during installation or a very short time after installation. This would not be unheard of in an area like a wing where there are several complex curves over a large area.

This is a very different situation that most people are used to in real-life. Most things used on a daily basis (furniture, cars, houses, etc) have very high initial margins of safety to allow for poor maintenance, etc. This also allows for poor installation techniques.

The A380 likely has some aluminum panels that are 0.050" or less. (I do not have any knowledge on the A380, but Aircraft typically have aluminum panels ranging from 0.016" to .5" with even large models having some areas at <0.050") Consider how much force it would take to bend a 2" x 4" enough to displace the end 2" when your holding it 4", 6", 12", etc away. Consider how durable you would consider the resulting structure. That's what as little as an 0.050" (3/64") gap can do to an aircraft.

From the description, its very likely that
A.) A mechanic is installing the part outside standard installation procedures due to fabrication process difficulties (for example the part is warping during heat treatment)
B.) An engineer made an error is measuring tolerances and an unplanned for gap is occurring
C.) A plan writer is leaving off an important step. For example, deburring or fillet relief cutting holes such that fastener installation or hole cutting is leaving defects that turn into cracks.

None of these is particular unusual or something alarming.

It is unusual to have a private group of civil aviation engineers make a public statement about an issue. Clearly there is a mild/major disagreement how fast the problem should be fixed...


RE: That's just great !
By fteoath64 on 1/14/2012 2:40:44 AM , Rating: 2
" Clearly there is a mild/major disagreement how fast the problem should be fixed".

The article suggested that a 4-year inspection cycle meaning another 2 years for a plane that is 2 years old. This is certainly UNACCEPTABLE even though it might be stated in the contract becuase "load bearing" and "non-load bearing" can both severely affect steering accuracy,hence risking the lives of the passengers and crew.
One would suggest Airbus replace one such panel and test for its tensile strength and metal fatigue degradation in order to determine if immediate replacements is needed. It is only fair, don't you think ?.


RE: That's just great !
By FaaR on 1/9/12, Rating: 0
"What would I do? I'd shut it down and give the money back to the shareholders." -- Michael Dell, after being asked what to do with Apple Computer in 1997














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