With regards to the 500E and the hangar door I won't say where it happened or to whom, but if I remember correctly it went something like this:
Aircraft had just been completley overhauled, so was basically 'new' again. On the run up to do track and balance the collective was either raised slightly or was mis-rigged so that when full rpm was reached the aircraft was just light on the skids enough to move. And she did.
Two mechanics and pilot got away with minor cuts and bruises. The pilot was not wearing his seatbelt for the ground run and was thrown out and got pinned between the skid and the hangar door - very lucky not to have been seriously hurt. Always belt up!