Not strictly pre flight, although I had been on the ground. Rotors running single pilot so no way to walk around.
In a 212 returning to an offshore platform from a "liaison" visit to a village where the oilies were fixing their generator. 5 minute flight. Levelled out at about 400 feet and heard a knocking sound that seemed to be coming from the starboard side. Took off my headset, stuck my head out and saw a teenager standing on the skid clinging to the door handle. About turn, landed back at the village. Boy ran away but was caught by his compatriots who proceded to beat the Hell out of him. Took off and continued back to the platform.
Nobody tried that stunt again. I suspect they would have except for the consequences..........
NEO