Penultimate Failure

Airbus recently tested the wing of their new A380 to destruction. Unfortunately, it failed a little earlier than anticipated. The test that failed is known as the Ultimate Load test. It involves mounting a wing in a jig and bending the tip up to simulate the strain that the wing might face in service. The first series of tests are to the "Limit Load" — the maximum amount that the aircraft is to carry in service. The European aviation authorities then require the wing to withstand a strain of 1.5 times the Limit Load for three seconds before failing.

The A380 wing failed between 1.45 and 1.5 times the Limit Load. Airbus will attempt to convince the authorities to approve the wing based upon models of any changes, rather than testing another actual wing. This is in accordance with standard Airbus practice. The A330 wing also failed just short of the standard. Airbus actually points to the failure with pride, pointing out how it means that there is no wasted weight spent on excessive strength, as compared with the Boeing 777 which didn't fail until 1.54 times the Limit Load.

While there is something to be said for avoiding excessive conservatism and the fact that the wing did fail at precisely the point predicted by the models, I'd prefer to fly on a plane that had been designed with the extra little bit of strength built in.