What happened
On the morning of 15 September 2021, a Robinson 44 Raven II, registration ZS-HBH, was conducting a livestock counting mission at the Tilodi Game Reserve in Leeupoert, Limpopo. The flight was being operated under Part 91 regulations for private use. While flying at a low altitude and a slow speed of approximately 20 knots, the pilot spotted a herd of buffalo.
In an attempt to reposition the aircraft so the passengers could get a better view of the animals, the pilot initiated a right-hand turn. This maneuver placed the helicopter into a downwind position. At this moment, the aircraft was operating with a high power setting of approximately 21 inches of manifold pressure, but the low airspeed and the nature of the turn caused the helicopter to run out of power. Because the aircraft was at such a low altitude, there was insufficient height to recover from the descent, leading to a ground impact. The aircraft suffered substantial damage, though the pilot escaped without injury.
The investigation
An investigation into the occurrence established that the pilot held a valid Commercial Pilot Licence and the aircraft possessed a valid Certificate of Airworthiness. Meteorological data from the South African Weather Service indicated a temperature of 25˚C, resulting in a density altitude of 4,500 feet.
Technical analysis revealed that the manifold pressure required to maintain sustained flight at that altitude was approximately 21.9 inches, which exceeded the power setting the pilot had actually selected during the maneuver. No mechanical defects or warning lights were reported by the crew prior to the impact.