The helicopter, with two persons on board, had just taken off from a private helicopter pad at the owner’s premises at Glenbeigh. At 600 ft the pilot heard noises from his rear, witnessed a drop in engine RPM and decided to autorotate for an immediate landing on the beach. On touchdown, one of the helicopter’s left skids collapsed and one of the main rotors struck the sand. The tail rotor assembly separated from the helicopter and the tail boom structure tore from the fuselage. The occupants exited the helicopter unaided.