Primary finding
Probable cause
The pilot’s failure to control his rate of descent during autorotation, which required an aggressive recovery maneuver and resulted in a sudden loss of tail rotor effectiveness.
Investigator assessment
Analysis narrative
The private pilot was conducting a practice 180-degree power recovery autorotation in a helicopter with a clockwise rotating main rotor with a right crosswind of three knots. The pilot said he had a higher than expected rate of descent as he was flaring at zero airspeed and attempting a power recovery to terminate at a skid height of approximately 15 feet above ground level. Suddenly, and without warning the pilot lost directional control, the helicopter began to spin nose left, and his application of full right pedal had no effect. The pilot said he tried to keep the helicopter level while it was spinning, but it eventually impacted on the left side of the taxiway. The helicopter was substantially damaged when the left skid gear partially collapsed and the airframe and tail boom buckled. During the impact sequence the main rotor blades struck the tail boom and the main rotor blades and tail rotor blades struck the ground. An on-scene investigation by an FAA maintenance inspector confirmed flight control continuity and confirmed no apparent damage to the tail rotor drive belts. There was no post-crash fire and the pilot received minor injuries.
Source record
Factual narrative
The private pilot was conducting a practice 180 degree power recovery autorotation in a helicopter with a clockwise rotating main rotor with a right crosswind of three knots. The pilot said he had a higher than expected rate of descent as he was flaring at zero airspeed and attempting a power recovery to terminate at a skid height of approximately 15 feet above ground level. Suddenly and without warning the pilot lost directional control, the helicopter began to spin nose left, and his application of full right pedal had no effect. The pilot said he tried to keep the helicopter level while it was spinning but it eventually impacted on the left side of the taxiway. The helicopter was substantially damaged when the left skid gear partially collapsed and the airframe and tail boom buckled. During the impact sequence the main rotor blades struck the tail boom and the main rotor blades and tail rotor blades struck the ground. An on-scene investigation by an FAA maintenance inspector confirmed flight control continuity and confirmed no apparent damage to the tail rotor drive belts. There was no post-crash fire and the pilot received minor injuries.