Primary finding
Probable cause
The pilot's failure to maintain adequate main rotor rpm during a practice autorotation. Contributing to the accident was the instructor pilot's delayed remedial action.
Investigator assessment
Analysis narrative
The instructor pilot was performing flight checks on the single-engine helicopter after maintenance had been performed. The instructor pilot and private pilot on board had completed three straight-in autorotations and one 180-degree reverse direction autorotation. The instructor set up on downwind and initiated a second 180-degree autorotation. When the turn was almost completed, the rotor RPM started to drop. The instructor decided to initiate a power recovery go-around. Power was applied but the helicopter continued to settle and hit the ground in a level attitude. The helicopter rolled on its left side and sustained substantial damage. Both occupants exited the aircraft unassisted and were not injured. No system anomalies were discovered.
Source record
Factual narrative
The instructor pilot was performing flight checks on the single engine helicopter after maintenance had been performed. The instructor pilot and private pilot on board had completed three straight-in autorotations and one 180-degree reverse direction autorotation. The instructor setup on downwind and initiated a second 180-degree autorotation. But, when the turn was almost completed, the rotor RPM started to drop. The instructor decided to initiate a power recovery go-around. Power was applied but the helicopter continued to settle and hit the ground in a level attitude. The helicopter rolled on its left side and sustained substantial damage. Both occupants exited the aircraft unassisted and were not injured. No system anomalies were revealed.