What happened
On 11 August 2003, a Robinson R2 and2 Beta, registration G-CHYL, was conducting a trial lesson near Bournemouth Airport. During the descent toward the airfield, the pilot performed standard pre-landing checks and transitioned the carburettor heat from hot to cold once below 300 feet to optimize engine performance in the warm ambient temperature.
During the approach to Runway 08, the pilot observed the low rotor-speed warning horn and the associated warning light. In an attempt to recover rotor speed, the pilot lowered the collective lever and increased the throttle. During this period of high descent rate, the passenger instinctively grabbed the cyclic control, momentarily causing a flare. The pilot managed to steer the aircraft away from active runways and buildings, but the helicopter ultimately struck the ground heavily near a disused runway. The impact caused the right skid gear to bend and resulted in minor structural distortion to the cabin.
The investigation
The AAIB examined the aircraft and found no technical defects in the engine, which ran smoothly upon inspection. Investigators noted that the governor switch was found in the OFF position, though the pilot believed this was done after the aircraft had come to rest.
A photograph taken by the passenger during the final descent provided critical evidence, showing the low rotor RPM warning light illuminated, a descent rate of 400 feet per minute, and a forward airspeed of 27 knots. Analysis of the wind conditions indicated a 10-knot tailwind component during the landing. The investigation also considered whether the governor had been inadvertently switched off prior to the descent, which could have contributed to the low power state.
Findings
- The aircraft was in a low energy state during the final approach, characterized by low forward speed and low rotor RPM.
- The heavy landing was likely a result of the inability to recover rotor speed above the warning threshold before touchdown.
- The passenger's instinctive movement of the cyclic control contributed to the flight dynamics during the descent.