What happened
On 7 May 2003, a Eurocopter AS 350-B3, registration ZS-RPD, was conducting a South African Police Service (SAPS) crime prevention mission in the lower Drakensberg region. While orbiting a kraal in the Wonder Valley area at an altitude of approximately 50 to 100 feet, the crew and three passengers spotted a suspected marijuana field. Upon seeing an individual fleeing the area with two bags, the pilot performed a right turn to maintain visual contact with the suspect.
Following this maneuver, the pilot noticed the aircraft was descending. Although the pilot leveled the aircraft and increased the collective pitch, the helicopter continued to lose altitude. The aircraft eventually struck a maize field in a level attitude. During the forward movement, the left skid assembly caught the ground, causing the helicopter to roll forward and to the left into a ditch. All four occupants survived the impact without fatalities.
The investigation
Investigators examined the flight data and the circumstances surrounding the maneuver. The investigation focused on the aircraft's performance during the turn and the subsequent loss of altitude. Data retrieved from the Digital Engine Control Unit (DECU) provided critical information regarding the engine's operational state during the descent.
Findings
- The pilot's attention was diverted while attempting to track the suspect during a turn and deceleration maneuver.
- This distraction likely led to a significant decay in main rotor RPM, which dropped as low as 320 rpm.
- Although the pilot attempted to recover by increasing collective pitch, there was insufficient altitude to prevent the continued descent.
- The impact occurred while the aircraft was in a level attitude, followed by a rollover caused by the left skid digging into the terrain.