What happened
On 26 December 2016, a Robinson R44 II helicopter, registration ZS-HXX, departed Stellenbosch Airfield (FASH) for a private flight to Worcester Airfield. The flight began without incident; however, while cruising at approximately 2,000 feet above ground level over Stellenbosch, the pilot observed the governor warning light illuminate. Despite attempts to reset the system by cycling the governor switch and checking circuit breakers, the warning persisted.
Seeking to return to the departure airfield, the pilot initiated a diversion to Stellenbosch. While performing a turn for the final approach to runway 19, a low rotor RPM warning sounded. Due to the low altitude at this stage of the maneuver, the pilot opted to perform an emergency landing at the nearby De Zalze Golf Estate. During the touchdown, the aircraft struck the ground heavily and rolled onto its right side, causing the main rotor blades to impact the terrain.
The investigation
An investigation by the SACAA AIID examined the flight history and the mechanical state of the aircraft. The aircraft, which had only 231 total airframe hours, had undergone its last annual inspection less than four flight hours prior to the accident. The investigation confirmed that the pilot held a valid private pilot license and medical certificate at the time of the event. The physical inspection of the wreckage revealed damage to the tail rotor, the skids, and the main rotor blades.
Findings
- The primary cause of the accident was an unsuccessful forced landing resulting from low rotor RPM.
- A governor failure acted as a contributing factor, necessitating the initial diversion and subsequent loss of engine-governed stability.