What happened
On 25 September 2003, a Robinson R22 Beta, registration ZS-RLY, was engaged in a game-darting mission near Farm Waterfall, close to Machadodorp, Mpumalanga. The pilot and one passenger departed from the farm, flying south along mountain contours at an altitude of roughly 5,200 feet above mean and sea level. As the crew entered a gorge to approach the target area, the pilot began a clockwise descending turn to adjust for their altitude. During the third turn of this maneuver, the aircraft entered an uncontrolled clockwise spin. The pilot attempted to recover by applying full left yaw pedal and lowering the collective pitch, but the rotation continued until the aircraft struck several trees and settled on the ground in a nose-down position.
The investigation
Investigators examined the wreckage at an approved maintenance facility to identify any mechanical discrepancies. The inspection of the airframe revealed no evidence of mechanical malfunctions or failures occurring prior to the impact. Maintenance records showed that the helicopter's last mandatory periodic inspection (MPI) was completed on 28 July 2003, with 92.6 flight hours accumulated since that service. The pilot held a valid commercial license with the appropriate type and livestock ratings. The investigation also reviewed the pilot's recovery attempts, noting that the pilot reported a loss of tail rotor thrust and an ineffective response to left pedal input.
Findings
- The aircraft experienced a sudden loss of tail rotor thrust during the descent.
- The pilot's attempt to use left yaw pedal was ineffective because, according to the Pilot Operating Handbook, left pedal application does not correct the specific yaw effect encountered in this scenario.
- The aircraft sustained substantial damage during the impact with trees and the ground.
- The pilot sustained one injury (a fractured hand), while the passenger remained uninjured.