Explanation Of Mast Bumping

[mnewbery]

1980 US Army video explaining mast bumping in the UH-1 and AH-1 helicopters with teetering main rotor hinge design. This is the same design used in many two bladed examples such as the Robinson R22 and R44. Mast bumping has been implicated in a number of high profile civillian fatalities in Australia, especially if resulting in a tail rotor or cockpit contact with the main rotor blade

 

Fast forward to about 11:20 for the brief description