Yes, an F-117A lost a wing at an airshow in the 1990s. The problem turned out to be control surface flutter caused by faulty maintenance. As for C-5s, their problem was with the wings cracking. None lost a wing in flight but for years the "A" models had to operate with weight restrictions. They were repaired some years ago and the B models never had the problem.

This morning, the NTSB is reporting that the plane's cockpit voice recorder caught the plane shaking fairly violently twice before the crash. After the first incident, the copilot mentioned that he thought it was due to turbulence from a plane that had taken off ahead of them. I know of several incidents where a smaller plane was brought down by wake turbulence but I don't know of any airliners brought down that way. It seems unlikely (but not impossible) that the turbulence might've overstressed the vertical stabilizer and caused the crash.