"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 ..."
Do they do any sort of shear test on wings? Or is shear not an issue wuth these constructions?
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.
My understanding of what they said was they do the wing load test on all the new models ... I don't think they do it anymore on production airplanes ...