Primary finding
Probable cause
The student pilot's improper use of the flight controls while performing a hovering autorotation and the flight instructor's excessive remedial action which resulted in a hard landing.
Investigator assessment
Analysis narrative
The flight instructor reported that he and his student were practicing hovering autorotations. After the student successfully performed two hovering autorotations from a height of 2 inches, the flight instructor had the student bring the helicopter to a 1-foot hover. During initiation of the maneuver from this altitude, the student pilot applied full right pedal and began to roll the throttle on, which "immediately resulted in substantial right yaw." The flight instructor corrected by adding left pedal, rolling the throttle off, and lowering the collective. These actions overcorrected for the right yaw and resulted in a left yaw. As the skids touched the ground, the flight instructor fully lowered the collective. The aft cross tube was bent, and the tail boom was wrinkled.
Source record
Factual narrative
The flight instructor reported that he and his student were practicing hovering autorotations. After the student successfully performed two hovering autorotations from a height of 2 inches, the flight instructor had the student bring the helicopter to a 1-foot hover. During initiation of the maneuver from this altitude, the student pilot applied full right pedal and began to roll the throttle on, which "immediately resulted in substantial right yaw." The flight instructor corrected by adding left pedal, rolling the throttle off, and lowering the collective. These actions overcorrected for the right yaw and resulted in a left yaw. As the skids touched the ground, the flight instructor fully lowered the collective. The aft cross tube was bent, and the tail boom was wrinkled.