History of Flight
On 28 February 2015, a Robinson R44 Raven II helicopter, registration ZS-RUN, was operated on a commercial Part 127 flight. The pilot, accompanied by two passengers, took off from a private farm near Kambuka Private School in the Thabazimbi area, Limpopo, to observe game on a neighboring farm. The helicopter was flown at approximately 50 feet above ground level and 16 knots forward speed. The pilot executed a 90-degree right turn, flying downwind. Immediately after, the helicopter lost height and descended rapidly, striking the ground in a 15-degree nose-down attitude.
Injuries and Damage
The pilot and one passenger sustained serious injuries, while the other passenger suffered minor injuries. All occupants were taken to hospital by ambulance. The helicopter was substantially damaged in the accident sequence. The main rotor hub assembly broke from the root attachment, and the main rotor blades sustained substantial damage, including evidence of collision with trees. The windshield shattered on impact.
Investigation Findings
Post-accident inspection of the engine revealed no anomalies in performance or functioning. The investigation determined that the helicopter descended rapidly and struck the ground while flying at low height with a tailwind component. The pilot reported no RPM split indication or unusual sounds during the accident sequence. Low rotor RPM was identified as the cause of the crash. The mass and balance were within limits, and weather conditions were reported as good with wind from the northeast at 10 knots, temperature 30°C, and CAVOK visibility.
Probable Cause
The probable cause of the accident was failure by the pilot to maintain main rotor RPM during operation.