Worst I ever heard and almost caused a loss of control of my own aircraft it was so sudden and frightening.

It was a three pole 428 (Q-500) race at Speedworld (PHX) The teams fly from roughly not quite between the #2 and #3 poles and you are rather close as the airplanes round two and three. The airplane that suffered the flutter occured between two and three and it was not a control surface flutter but instead the entire wing. The sudden burst of high frequency wing flutter was extrodinary.

Even more extraordinary was the fact that the airplane did not crash. Of course the airvalve was shut down immediately and the gentleman was able to land. On that shoulderwing airplane four bolts secure the wing and both rear bolts were missing. Its not clear if the ossilations backed out the bolts or perhaps poorly tightened bolts had precipitated the incident. The only thing holding the wing was the two forward bolts at the leading edge and the trailing edge could flop up and down about an inch.

John