Flutter
Great article on flutter and why it is a problem for pilots. Breakups in flight because of flutter are rare because of the extensive testing that is done by manufacturers.
This is the video of the Commanche flutter test.
And one of a Boeing 747.
And a longish one on what went into testing the Airbus A380.
Experimental aircraft don’t go through the same kind of testing and breakups are much more common. Flutter is suspected in the breakup of several Zenith kit-built aircraft. AOPA has an article on it here. Zenith has issued a patch kit to address the breakup issues.
AOPA has a Flash page about flutter on a clear day in Alaska. (Members Only)
And if that’s not enough. Here’s a full page of NASA flutter tests.