History of Flight
The pilot and a crew member were conducting game counting operations at ZZ2 Game Farm in the Moketse area, Limpopo Province. On 27 September 2016, they completed several uneventful flights. On 28 September, they continued operations from approximately 0500Z, completing two more flights, with the final landing at ZZ2 Game Farm around 1400Z. The helicopter was refuelled to capacity, and the intention was to fly to their main base at Tankerton Farm, about 62 km southeast.
At approximately 1450Z, the helicopter took off and routed southeast. About three minutes into the flight, the crew member heard an unusual noise from the engine, as if it were powering down. No warning lights or audible warnings were observed. The pilot did not communicate verbally. The helicopter began to descend, and the pilot attempted to flare and execute an autorotation into a dry river bed. The autorotation was unsuccessful, and the helicopter struck trees before impacting the ground on the bank of the river bed. A post-impact fire engulfed the wreckage.
Injuries to Persons
The pilot sustained fatal injuries and succumbed to his injuries. The crew member sustained serious injuries but managed to exit the wreckage and call the operator at 1502Z.
Aircraft Information
The aircraft was a Bell 206B helicopter, serial number 4124, manufactured in 1990, with registration ZS-RFC. It was owned and operated by Big Game Heli Services CC. At the time of the accident, the total airframe hours were 2929. The engine was a Rolls Royce 250-C20J, serial number CAE-270507, with 2929 hours since new and 1324.8 hours since overhaul. The last maintenance inspection was performed on 9 September 2016 at 2900.7 hours. The Certificate of Airworthiness and Certificate of Registration were valid.
Personnel Information
The pilot, aged 31, held a South African Commercial Pilot License with a helicopter rating and a valid Cull Rating for game/livestock. His total flying experience was 5837.2 hours, including 202 hours on the Bell 206B. His license was valid, with a medical expiry date of 30 June 2017.
Meteorological Conditions
The accident occurred during daylight at approximately 1455Z. Weather information from the South African Weather Service indicated wind from an unspecified direction at 2 knots, visibility 10 km, temperature and dew point not recorded, no cloud cover, and no significant weather in the area.
Impact and Wreckage
The first point of impact was a large tree approximately 20 meters from the river bed. The helicopter then descended through smaller trees before impacting the ground on its belly. The skids and doors separated, and the helicopter bounced and came to rest 10 meters away against the river bank. The wreckage distribution indicated high forward speed at impact. A post-impact fire destroyed the helicopter. The main rotor blades showed decay in rotor RPM before impact.
Probable Cause
The investigation determined that the probable cause was an unsuccessful autorotation following an in-flight engine failure, caused by the separation of a 2nd stage turbine blade due to progressive fatigue as a result of being operated at excessive temperatures.