The pilot of G-RAMY, a Bell 206B Jet Ranger II, had disembarked his two passengers and lifted off for the return flight, in an area of mountainous terrain. The wind was from 220-230°, gusting to 46 kt and the aircraft was seen to head initially into the wind. It was then seen to turn right onto a north-easterly track and the fuselage was seen to oscillate in roll. The fuselage then rotated in yaw beneath the rotor disc, more than once, and the nose of the helicopter pitched up into the rotor disc, being destroyed as it did so. The fuselage of the helicopter, its rotors and many fragments then fell separately to the ground, where the fuselage impact was not survivable for the pilot.
Examination of the wreckage showed that there had been a catastrophic failure of the helicopter’s main rotor mast in flight and there was clear evidence that this had been due to heavy ‘mast bumping’ contact between the teeter (‘static’) stops on the main rotor head and the main rotor mast. This was consistent with the observed behaviour of the helicopter, where the pilot appears to have been attempting to control the aircraft in turbulent conditions.