History of Flight
On 15 April 2016, a commercial pilot accompanied by a passenger (a veterinarian) conducted a game darting operation on a privately owned farm west of Lanseria Airport, Gauteng. The flight departed from Rand Aerodrome under visual flight rules. After a pre-flight inspection and normal engine start, the helicopter flew northwest at approximately 500 feet above ground level. On approach to the farm, the pilot descended at about 300 feet per minute. At roughly 10 feet above ground level, while preparing to dart springboks, the low rotor RPM warning horn sounded and the amber red warning light illuminated. The pilot observed the main rotor RPM at about 88%.
The pilot reported that a three-meter-high perimeter fence lay ahead. To avoid colliding with the fence, he raised the collective and opened the throttle. The helicopter cleared the fence but within seconds entered an uncontrolled descent and struck the ground heavily on the skid gear. The main rotor blade severed the tail boom, but the helicopter remained upright.
Injuries and Damage
The pilot sustained minor head injuries; the passenger was unharmed. The helicopter sustained substantial damage to the instrument panel, tail boom, tail rotor, main rotor blades, and skid gear.
Probable Cause
The investigation concluded that the loss of control and subsequent hard landing resulted from the pilot's failure to maintain rotor RPM.