Once the blades have seperated from the mast they are free to go anywhere. My only direct experience of mast bumping was observation of a Huey that sufferred same and tail boom was chopped off about six inches aft of the tail boom attatchment - and as if it had been a hot knife through butter it was such a clean "cut". And with 17 on board at 1000 - 1500 feet. Result of a zoom climb I might add.