Ever wonder how those guys and gals at Boeing know if their design for an aircraft is as safe as they hope it is? Finding this out comes by testing each individual component for stress, fatigue, and wear. Not only is this done for the small components, but also the larger parts as well. This clip comes from a great 5 hour documentary on the building of the Boeing 777, the first commercial airliner to be designed almost entirely by computers.
In this test, force is applied to the wing via pulleys, testing the pressure on the wing until…SNAP!