History of Flight
On Wednesday 28 February 2018 at 0945Z, a pilot accompanied by a passenger departed from Farm Truter Boerdery near Ogies, in South Africa's Mpumalanga Province, for a private flight under visual flight rules. The intended landing location was the same farm. Weather conditions at the time were reported as good, with surface wind from 080° at 6 knots, temperature 25°C, dew point 12°C, and QNH 1023.
A witness located approximately 580 meters from the accident site observed the helicopter flying in the vicinity of the farm for about 20 minutes. During this time, the helicopter performed maneuvers including out-of-ground-effect (OGE) hover turns and steep turns, at a height of about 100 meters (328 feet) above ground level. The witness reported that while the helicopter was flying in a northerly direction, a loud bang was heard, followed by a change in engine noise. The tail section was then seen separating from the helicopter in flight. The helicopter subsequently spiraled uncontrollably, rotating nose-right (clockwise when viewed from above) while descending nose-down, and crashed near a farm dam. A post-impact fire immediately erupted.
The witness ran to a workshop to retrieve fire extinguishers and used approximately eight dry powder extinguishers to contain the fire. Other farm workers and firefighters also arrived and applied water to the burning wreckage. Police and emergency services were alerted and arrived on scene approximately 30 to 40 minutes later.
The severed tail section was found approximately 350 meters southwest of the main wreckage. The main wreckage was destroyed by impact and the post-impact fire, and was lying on its left side, facing north. Both occupants were fatally injured.
The accident occurred during daylight hours at coordinates 26°2'12.79" South 028°53'56.06" East, at an elevation of 4944 feet above mean sea level.
Investigation
The investigation determined that the main rotor blade severed the tail section in flight during a steep turn to the right. As a consequence, the helicopter spiraled to the right in a nose-down attitude, crashed, and caught fire. The cause of the main rotor severing the tail cone was attributed to an incorrect technique during the execution of the steep turn.
Aircraft and Pilot Information
The helicopter was a Robinson R44 Raven II (registration ZS-HKZ, serial number 13253), manufactured in 2012. It was powered by a Lycoming IO-540-AE1A5 engine. At the time of the accident, the airframe had accumulated 346.0 total hours. The last maintenance inspection (MPI) was performed at 319.3 hours, and the helicopter had flown 26.7 hours since that inspection.
The pilot, aged 57, held a valid Private Pilot Licence (helicopter) issued in April 2017, with a type endorsement for the R44. His total flying experience was 157.9 hours, all on the accident helicopter type. His last flight skills test was conducted on 30 March 2017. The pilot's medical certificate was valid with a restriction for corrective lenses. The pilot had been involved in a previous accident with the same helicopter on 24 February 2016, which resulted in major structural damage; repairs were subsequently carried out in accordance with manufacturer specifications.