What happened
On the afternoon of 19 May 2017, a Robinson R44 Raven II helicopter, registration ZS-HFF, departed from Nampo Park near Bothaville for a private flight to De Hoop farm. The aircraft was carrying the pilot and three passengers under clear visual meteorological conditions.
While flying over Ongegund farm near Heilbron, an eyewitness observed a sudden change in the engine'-s sound, followed by the aircraft descending rapidly in a nose-down attitude. Although the pilot attempted to execute an autorotation—evidenced by the aircraft pitching upward just before impact—the helicopter struck the ground with high velocity. The force of the impact was so severe that the main rotor severed the tail boom, and the aircraft's skids collapsed upon contact.
The accident resulted in two fatalities, including the pilot and one teenage passenger. Two other passengers, an adult male and a 14-year-old male, sustained serious injuries and were transported to a hospital in Alberton.
The investigation
SACAA AIID investigators examined the wreckage and interviewed survivors to reconstruct the flight sequence. Post-impact analysis confirmed that the aircraft hit the ground at a high rate of descent. The investigation noted that the pilot had been actively manipulating the cyclic controls during the descent, and a surviving passenger recalled seeing the clutch light illuminate following a loud bang.
Technical examinations of the engine, flight controls, and various components revealed no mechanical malfunctions or defects in the aircraft's systems prior to the event. The investigation also confirmed that the aircraft was within its maximum takeoff weight limits at the time of the accident.
Findings
- The primary cause of the accident was an undetermined engine stoppage.
- The pilot attempted an autorotation maneuver, but the high rate of descent at impact led to the destruction of the aircraft.
- The high-velocity impact caused the main rotor to sever the tail boom and resulted in the separation of several structural components.