What happened
On the morning of January 12, 2002, a Robinson R-44 (Raven), registration ZS-RMM, was involved in a fatal accident near the Cathedral Peak Hotel in the Drakensberg Mountains. The flight originated from a private landing area at Bell Park Dam, where the pilot and three passengers had been staying. The intended destination was the hotel helipad for the purpose of refueling.
Upon arriving at the hotel, the pilot noted a momentary low rotor RPM warning during the landing phase. After the two rear passengers disembarked, the aircraft was repositioned and refueled to its full capacity. Before departing the helipad, the pilot consulted with another pilot regarding the current load. To ensure safety, the pilot performed two hover checks to verify the power available for the intended takeoff. Both tests successfully maintained a hover at 22 inches of manifold pressure. Believing the aircraft was within safe operating limits, the pilot proceeded with the takeoff. However, as the aircraft climbed out of ground effect, the rotor RPM began to decay rapidly, triggering the cockpit warning horn and resulting in a descent that ended in a crash approximately 0.2nm from the takeoff point.
The investigation
SACAA AIID investigators examined the flight circumstances, the aircraft's performance during the pre-takeoff hover checks, and the environmental conditions. The investigation focused on the weight and balance of the aircraft during the departure from the Cathedral Peak Hotel helipad and the subsequent loss of engine/rotor performance.
Findings
- The aircraft's weight exceeded its in-ground effect (IGE) hover capability by approximately 147 pounds.
- The pilot attempted a takeoff with four adult occupants, which rendered the aircraft too heavy to maintain safe flight once ground effect was lost.
- The pilot permitted the main rotor RPM to drop below the minimum safe threshold, as indicated by the activation of the audio and visual warning systems.
- The loss of rotor RPM prevented the pilot from achieving the necessary airspeed to sustain flight, leading to the impact.