I have had a near one in a Hughes 500. End of a fuel cycle while lifting so ac very very light with a 35 knot wind. landed on a plastic trackway that was being used by vehicles to get to the lift site. Refueller starts refuelling, muggins here stretches legs out ( already done 4 hours ) . Not really concentrating as pouring a coffee out of a flask. Looked up to see ac starting to rotate to left, as one knows take feet of a 500 pedals and it will pull full left pedal ( machine was at idle ). Interesting conversation with re fueler who was trying to stop the ac rotating by using his shoulder !