Posted on 02/16/2006 2:01:08 PM PST by A.A. Cunningham
Airbus A380 test wing breaks just below ultimate load target
The wing of the Airbus A380 static test specimen suffered a structural failure below the ultimate load target during trials in Toulouse earlier this week, but Airbus is confident that it will not need to modify production aircraft.
The airframer has been running load trials on a full scale A380 static test specimen in Toulouse since late 2004 (pictured below). After completing “limit load” tests (ie the maximum loads likely to experienced by the aircraft during normal service), progressively greater loads have been applied to the specimen towards the required 1.5 times the limit load. Engineers develop finite element models (FEM) to calculate the load requirements.
“The failure occurred last Tuesday between 1.45 and 1.5 times the limit load at a point between the inboard and outboard engines,” says Airbus executive vice president engineering Alain Garcia. “This is within 3% of the 1.5 target, which shows the accuracy of the FEM.” He adds that the ultimate load trial is an “extremely severe test during which a wing deflection of 7.4m (24.3ft) was recorded”.
The European Aviation Safety Agency (EASA) says that the maximum loading conditions are defined in the A380 certification basis. “The aircraft structure is analysed and tested to demonstrate that the structure can withstand the maximum loads, including a factor of safety of 1.5. This process is ongoing and will be completed before type certification.”
However Garcia says that the failure of the wing below the 1.5 target will require “essentially no modifications” to production aircraft: “This static test airframe has the first set of wings built, and we have refined the structural design for subsequent aircraft due to increased weights etc. We will use this calibration of the FEM to prove the adequacy of the structure on production aircraft.”
EASA says that it is aware of the structural failure but "cannot make a statement about the specific failure as it has not been officially briefed by Airbus on what the cause was, and the certification process is ongoing".
Garcia says that the FEM calculations had already established that the A380’s wing had “no margin at ultimate load. We had a weight saving programme and ‘played the game’ to achieve ultimate load.” However in earlier briefings, Airbus structural engineers had stated that it planned to carry out “a residual strength and margin research test” in 2006 after completing ultimate load trials.
The results gleaned from the static testing will be extrapolated for the future aircraft developments over the next 40 to 50 years says Garcia. “It is normal to refine and strengthen the structure of new heavier or longer range variants,” he says.
MAX KINGSLEY-JONES / LONDON
Argh.
Yes, you're quite correct, but the ULoad is meant to address non-every-day-use, and should have margin itself. The static test should give an indication of the real margin. Playing the game, as they termed it, will cause the plane damage in severe conditions, and the failure of this test insures they will have a difficult time accurately predicting the failure stress.
They have screwed La Chien with this.
7E7 - Yeah, baby!
What is the french word for "OPPS!!"?
A-380 Ping!
Mmmm... C-17! They fly one over the house every year during the airshow, monster low.
I'm not entirely surprised that C-17 did have a similar problem, but this is a passenger plane in this story. Their lack of conservatism in design is a physical and perceptual problem for their customer base.
I take this is not a good result for Airbus.
I wonder if they will quietly re-write the specs for Va, Vb, Vne, Vno?
If it ain't Boeing, I ain't going.
We were flying along, nice as you please, halfway across the Atlantic Ocean, when the wing fell off. I was shocked, I tell you...shocked!
Heh. Perhaps so.
An entire aircraft for this test. One or two prototypes are built for testing to destruction. They simply pull up on the wings and see how much deflection occurs before the wings break. The usual goal is 150% of design limit load. Looks like they hit 147% which is still quite good.
The video I have of the Boeing 777 wing test showed they got to 154% of design limit load before the wings broke. When the wings let go, it sounds like a cannon going off.
"And still flunks the test even though they've written the test."
Exactly. Much more succinctly put than I was saying.
Wouldn't beefing up equal higher fuel consumption? As I recall from reading a while back, they already had a problem meeting the fuel consumption standards they advertised to their customers.
I've had several British cars. I've had one French car. None of them were worth a darn, although the British cars were cute.
I'll not be flying this aircraft, thanks very much. One Pugeot was more than enough for me to understand French engineering excellence.
§ 25.303 Factor of safety. Unless otherwise specified, a factor of safety of 1.5 must be applied to the prescribed limit load which are considered external loads on the structure. When a loading condition is prescribed in terms of ultimate loads, a factor of safety need not be applied unless otherwise specified.
Federal law, ours and EASA, says they are screwed
The Boeing 777 went 157% of wing load before it broke ... I saw it in a video during a tour at the Everett plant ....
Aren't these the people who's tail fin broke off in NYC in 2001 killing like 280 people???
Airbus: We've got it Close Enough
Regular, or extra crispy?
At the Boeing plant in Everett they have a 767 that they never were able to break the wing. We saw it during a tour. The whole fuselage twisted but the wing never broke ...
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