Incident
On 12 August 2000, at 1420 hours UTC, a private flight in a Robinson R22 Beta (registration G-BYHD) encountered a low rotor RPM situation during approach to a private landing site. The aircraft had been airborne for approximately 15 minutes. As the pilot made the approach, the low rotor RPM warning horn activated and rotor RPM was observed decreasing. At about 500 feet above ground level, the pilot initiated an autorotation and selected a field ahead for landing.
During the flare, the helicopter was close to the ground but with little apparent decrease in forward airspeed, the pilot tightened the flare. The helicopter then landed heavily, making tail contact with the ground, and bounced forward. During the bounce, G-BYHD rotated to the right. Subsequent initial ground contact was on the left skid, and the helicopter remained upright.
Damage
The engine support frame was damaged, the landing skids were splayed, and damage occurred to the tail boom, vertical stabiliser, and tail rotor blades. No injuries were reported among the one crew member and one passenger.
Pilot Experience and Conditions
The pilot, aged 38, held a Private Pilot's Licence with an Instructor Rating and had 590 hours total flying experience (550 on type), with 5 hours in the last 90 days. The reported weather conditions in the operating area were: calm wind, visibility 20 km, overcast cloud base at 1,500 feet agl, and air temperature 18°C. The pilot described the day as "very moist."
Investigation
The pilot stated that the loss of rotor RPM was probably caused by carburettor icing. He noted that he was aware of the need to apply carburettor heat prior to descent but could not be certain when he had done so on this flight. The repair agency confirmed that no unserviceabilities were found with the helicopter that would have caused the loss of rotor RPM. The pilot also confirmed that the engine appeared normal after landing.