Primary finding
Probable cause
The student pilot’s failure to maintain helicopter control during a practice autorotation and the flight instructor's delayed remedial action.
Investigator assessment
Analysis narrative
The flight instructor reported that during an instructional flight, the helicopter was 500 feet above ground level when he rolled the throttle off with the intent for the student to respond by initiating a straight-in autorotation. The student pilot did not respond properly, so the instructor took the controls to initiate a power recovery. The helicopter subsequently landed hard, deforming both skids and substantially damaging the airframe. The pilot did not report any preimpact mechanical malfunctions or failures with the helicopter that would have precluded normal operation.
Source record
Factual narrative
The flight instructor reported that during an instructional flight, the helicopter was at 500 feet above ground level when he rolled the throttle off with the intent for the student to respond by initiating a straight in autorotation. The student pilot did not respond properly, so the instructor took over to initiate a power recovery. The helicopter subsequently landed hard, deforming both skids and substantially damaging the airframe. The pilot did not report any preimpact mechanical malfunctions or failure with the helicopter that would have precluded normal operation.