Accident Overview
On 9 August 2022 at 0720Z, a Robinson R44 Raven II helicopter (registration ZS-RSO) was involved in an accident at Stone Hill Game Farm in the North West Province, South Africa. The flight was conducted under Part 137 Aerial Work Operations for game capturing. One pilot and one passenger were on board. The pilot sustained injuries; there were no fatalities. The aircraft sustained substantial damage.
Flight Sequence
The pilot reported that while flying at approximately 50 feet above ground level (AGL) during the rounding up of the last giraffe into the boma, the giraffe turned and stopped facing the helicopter. The pilot executed a quick stop and aggressively pulled up the collective controls to gain height, intending to hover at a safer altitude because the helicopter was too close to the boma curtain. Simultaneously, the pilot attempted to move away from the boma curtain, as the main rotor downwash was preventing the ground team from closing it. This aggressive maneuver caused a decay in main rotor revolutions per minute (RPM), triggering the low main rotor RPM warning. The pilot attempted to recover but could not due to insufficient height. He then aimed for a gravel road to perform an emergency landing. However, the helicopter collided with a barbed wire fence before landing hard on the ground. During impact, the main rotor blades severed the tail boom.
Weather and Conditions
The weather at the time was reported as wind direction easterly at 7 knots, visibility 10 km, temperature 19°C, with clear skies. The helicopter was operating at a low height-velocity combination, as indicated by the height-velocity diagram.
Probable Cause
The probable cause of the accident was: During a game capture operation whilst the pilot manipulated the flight controls, the main rotor RPM decayed, which resulted in the helicopter losing height and crash-landing as there was insufficient height available to recover.