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
Your .380 will sell more. Boeing has enough orders for the Dreamliner to keep them busy for years. The A380 is already done. It doesn't get the mileage of the Dreamliner and it can't land at most airports due to its' weight. Airbus took a page from the U.S. automakers of the 70's - build it big with poor mileage so nobody will want one.
It surrendered as expected. Taping white flags to the wingtips did the trick.
Did anyone see the results of their ground test evacuating 600 people in 90 seconds? I have trouble believing that's possible.
It takes 89 seconds to open the belly door and 1 second to pull the lever.
Airliner manufacturers have learned from the experiences of structural fatigue (ever since the unfortunate de Havilland Comet accidents of 1953-1954) and nowadays do a lot a static structural testing to ensure the plane can last through many thousands of takeoff and landing cycles.
I read once that a typical reliability engineer was a fellow who would fly across the country on an airliner with a 1.5 safety factor to argue that a missile ought to have one of 8.0.
On an early B-707 transatlantic flight (with a load of passengers) there was some kind of autopilot malfunction, combined with the captain being back in the cabin passing out goodwill to the passengers; the ship got into a dive and they came close to losing it before it was back under control. A precautionary landing was made at Goose Bay or Gander. The wings were actually bent considerably. However, a thorough examination was made by a team of FAA and stress engineers and it was decided that the ship was safe to put back in service.
In engineering terms, this meant that "yield stress" was exceeded, but not "ultimate stress" which is typically about 1.5 times yield.
Thanks for the sources. Cheers!
He77 we don't even have tails on the A300-600's
I've fired the Bersa .380 and liked it. It's smaller and if I'm not mistaken, less expensive.
It was a landing problem, not a take off problem. The plane (E-2 Hawkeyes) could land, but it was at the edge of the deck and couldn't turn around. It had to be physically pushed back from the edge. The deck was lengthened at a cost of millions of Francs. (And then the prop fell off the ship). (And don't forget the radiation leaks from the reactor.)
Bersa, eh? That's the second recommendation I've had for that one. Thanks for the info.
Damn, I was gonna post Slim Pickens riding the bomb from Dr. Strangelove. :-)
It's France. There is something symbolic about a big disfunctional left wing on that eurobeast.
Or toutite. (Sorry, couldn't resist it).
I think it's "au'horsedouvers"
Sorry...I'll buy you a beer on our next Boeing flight. Just announce yourself when you see me.
Cheers...
Tou-che.
"The wings were actually bent considerably."
Geez, if the wings got bent in the recovery (pulling out of the dive) those poor people must have been subjected to some SERIOUS G's.
I wonder what the difference in wing shape would have done to the craft's flight/stall characteristics?
It often seems they were wonderfully unconcerned with minor details back in the day.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.