A friend of mine doing his training in an R22 was doing a nav with his instructor of course they were over wooded country at the time and the instructors door actually flew completely OFF!! GOOOOOONE!
The door broke from the bottom hinge and flew upwards ripping off the corner of the top hinge leaving the hinge and split pin still in place on the top. This is where it gets interesting!
Door flies off and upwards you can guess what happened next, straight through the MR and diced into confetti.
They proceeded to decend and land ASAP slight vibration throught the airframe was what my friend had told me but i can still see the fear in his eyes when he tells me the story again.
Landed , shutdown inspected the MR to find a nice little Indentation on the leading edge. Subsequently the aircraft was grounded untill the blades were replaced!!!