Snapped wing on new Airbus jet during test should set off alarms

If it ain't broke, don't fix it. Fine. But it did break.

On Tuesday, Feb. 14, a resounding crack echoed through the Airbus static test facility in Toulouse, France. The wing of Airbus' mammoth A380 had snapped between the inboard and outboard engines at an applied pressure approximately 1.45 times limit load — about 3.3 percent short of the planned ultimate load.

Just before the snap, an extreme wingtip deflection of 24.3 feet had been recorded.

Limit load is the highest aerodynamic load expected during an aircraft's lifetime of normal service — often 30 years or more. Ultimate load includes a built-in — and required — safety factor: 1.5 times limit load. Just to be sure.

Furthermore, we are talking about the huge, double-decked A380, a brand-new aircraft and the world's largest commercial jetliner, scheduled to enter service at the end of the year with Singapore Airlines. It will seat 555 passengers in three classes — far more in an all-economy configuration. It lists for about $295 million per aircraft, of which 159 have been ordered by 16 airlines around the world.

According to respected British aviation journal Flight International, Airbus' vice president for engineering, Alain Garcia, felt that the wing test had been a success since the rupture occurred "within 3 percent of the target, which shows the accuracy of the FEM [computerized Finite Element Modeling]." He went on to say that Airbus had planned for the A380 wing to have "no margin at ultimate load. We had a weight saving program and 'played the game' to achieve ultimate load."

Indeed, the test sample had been selected from the first set of wings built, unlike current production versions adjusted for expected growth of the aircraft. There was apparently no need to go past 1.5 to the 1.54 times limit load achieved by Boeing more than 10 years ago with its 777, building unnecessary strength and weight into its aircraft.

Playing games is fine. I don't know about you, but a 1.54 limit load safety margin on an aircraft carrying at least 555 passengers sounds pretty good to me.

Referring to the wing failure, "It's not a big problem at all," commented Airbus sales chief John Leahy in an Associated Press report from the recent Singapore air show. But it could be for the rest of us when we read that Airbus' A330 wing failed just below its target load in 1992, and when we think about the Nov. 12, 2001, American Airlines Flight 587 disaster that killed 265 people. That crash involved an Airbus A300-600R whose all-composite tail fin had snapped off the aircraft shortly after takeoff — the only time an entire tail fin has ever sheared off a commercial jetliner. Although not subjected to operationally realistic temperature and humidity conditions, it nevertheless had been fully tested to ultimate load, 1.5 times estimated limit load.

Unfortunately, the key fact remains that Airbus had clearly underestimated even limit loads for the A300. How accurate, then, are both projections for the new A380?

We will see how the European Aviation Safety Agency handles final certification of the A380 — not to mention the Federal Aviation Administration here in the U.S.

But the crash of any airliner carrying 555 or more passengers is no "game," and the fact that both the FAA and the National Transportation Safety Board failed to investigate what were probably key factors contributing to the AA587 disaster raises further concern about how they will evaluate Airbus' testing criteria and methods — and about whether they will certify the A380 for flights into and from the United States without requiring production changes to that wing.

Alain Garcia predicted the wing's failure will require "essentially no modifications" to production aircraft; last week another executive conceded that "maybe" minor local reinforcements might occur.

What will the FAA decide? As major hub airports around the world prepare their taxiways and terminals to handle this massive aircraft and the crowds it will bring, the traveling public needs reassurance that the skies it flies will be safe as well as friendly. Passengers deserve more than a wing and a prayer.

Lee Gaillard is a freelance writer based in Philadelphia who writes frequently on defense and aviation issues.