My old buddy Dan Durda sent me a note about an article on space.com about the recent failure of the Falcon 1 rocket from Space X. The failure was finally determined to be from an aluminum nut that was holding a pipe fitting in place. Corrosion on the part allowed fuel to leak, starting a fire which doomed the rocket.
The article's title? "Falcon 1 Failure Traced to a Busted Nut".
As Dan pointed out, launch crews obviously work very hard.