History of Flight
The helicopter, crewed by two licensed pilots, conducted a training flight under Visual Flight Rules by day. A comprehensive pre-flight inspection was performed, and the aircraft was refueled with Jet A1. Departure from Cape Town International Airport was normal, and the aircraft proceeded to the general flying area for a 6th-monthly operator's proficiency check for the trainee. The session began with simulated hydraulic failure and three simulated engine failures in hover. The crew then climbed to 1000 feet above ground level for autorotation practice. The first autorotation was successful: the instructor closed the twist grip to ground idle, the trainee entered autorotation, and the instructor reopened the twist grip during flare. The second autorotation was initiated from a downwind position at 1000 feet AGL. The instructor again closed the twist grip to ground idle. While monitoring the main rotor and engine N2 gauge, the instructor observed the engine RPM decreasing below normal idle indication. The instructor informed the trainee of an engine loss, and the trainee continued autorotation procedures until touchdown. Upon landing, the helicopter retained forward motion, skidding approximately 3 meters. The skids dug into soft terrain, rapidly reducing speed, and the main rotor severed the tail boom. Debris was seen flying to the left. The aircraft came to rest substantially damaged. Both pilots vacated the aircraft unharmed. Air Traffic Control was notified, and the crash alarm activated; fire and rescue services responded.
Injuries
Neither pilot sustained any injury.
Damage to Aircraft
The tail boom was severed by the main rotor blades. The main rotor blades were damaged, the pitot tube was broken, and the right windscreen shattered. A full inspection was required to assess hidden stress on the airframe and skids.
Wreckage Examination
Post-accident, the twist grip was found in the fully open (flight idle) position, and the fuel control unit quadrant indicated 60 degrees. The fuel shut-off valve was in the OFF/closed position.
Meteorological Information
Surface wind was 190° at 5 knots, temperature 22°C, visibility exceeding 10 km.
Probable Cause
The probable cause was an unsuccessful autorotation resulting in a hard landing due to undetermined loss of engine power.