What happened
On October 25, 2002, at approximately 15:30Z, a Robinson R22 helicopter, registration ZS-HLC, was engaged in a commercial game capture operation within the Nylsvlei Nature Reserve. The aircraft was performing a flight pattern within the reserve, having departed from and intended to return to the same location. During a turn performed down-wind, the pilot experienced a decay in the main rotor RPM. This loss of rotor speed led to a collision with the ground. While the pilot escaped the incident without injury, the aircraft suffered substantial damage.
The investigation
The investigation focused on the flight dynamics during the turn and the mechanical state of the aircraft. Meteorological conditions at the time of the accident were reported as fine, with a light north-westerly wind of 10 knots. The investigation confirmed that the aircraft was being operated under a valid commercial operator's license. Furthermore, the maintenance records indicated that the helicopter was being maintained according to prescribed intervals; the next major periodic inspection (MPI) was not due until July 2003 or upon reaching 4362 flight hours. At the time of the accident, the aircraft had flown 88 hours since its last MPI.
Findings
- The primary factor in the accident was the pilot's failure to maintain the Main Rotor RPM during the maneuver.
- The decay in rotor speed occurred specifically while the aircraft was executing a down-wind turn.
- Weather conditions were favorable and did not contribute to the loss of rotor stability.