What happened
On 14 October 2014, a Robinson R44 II helicopter, registration ZS-R44, was conducting a private local flight in the Limpopo province of South Africa. The pilot departed from the Krokodilstraat farm, intending to land at the Schwerin farm. Shortly after takeoff, while flying in an easterly direction, the aircraft's main rotor blade struck a tree in bushy terrain approximately 500 meters from the departure point.
The impact caused the rotor blade to fracture near the transmission assembly. This contact initiated a sequence where the helicopter rolled onto its left side while the rotors were still spinning. The crash resulted in a post-impact fire that consumed the primary wreckage. The pilot, the sole occupant of the aircraft, sustained fatal injuries during the impact and the ensuing fire.
The investigation
Investigators from the SACAA AIID examined the wreckage and the surrounding environment to reconstruct the flight path. The investigation established that the aircraft's tail boom and tail rotor remained intact, suggesting the initial impact was limited to the main rotor system. Although the post-impact fire was severe enough to destroy the cockpit, electrical systems, and the pilot's flying logbook, the engine was recovered and dismantled. A teardown of the Lycoming engine revealed no mechanical defects or malfunctions.
Meteorological data from the Thabimbi weather station indicated a temperature of 24 ºC and winds of 19 knots at the time of the accident. The investigation also noted that the aircraft was not equipped with flight data or cockpit voice recorders, as they were not required for this type of operation.
Findings
- The primary cause of the accident was the main rotor blade impacting a tree, which led to a total loss of control.
- The impact with the tree likely triggered a dynamic rollover, a condition where a lateral component of thrust causes the helicopter to roll uncontrollably.
- The aircraft was traveling at insufficient airspeed to establish an autorotative profile to avoid the obstacle.
- Prevailing weather conditions, specifically the 19-knot winds, likely contributed to the circumstances of the accident.