Accident Summary
A helicopter flight instructor was demonstrating an autorotation from an altitude of 50 feet above ground level (AGL) to a grassy landing area. The helicopter touched down with its skids level, and the instructor increased collective pitch to keep the skids lightly contacting the ground while maintaining a straight ground track. After traveling approximately 70 feet at a speed of about 20 knots, the aircraft pitched forward and to the right. The instructor reported feeling at least three severe impacts before the helicopter came to a stop.
Examination Findings
Post-accident examination of the helicopter revealed that both the left and right skid tubes were fractured. The right skid was detached from its front and rear gear dampers. Additionally, the tailboom and tail rotor had been sheared off by contact with the main rotor blades. Further inspection of the skid tubes showed that the bottom of the right skid tube was worn beyond the manufacturer's specified tolerances.
Inspection Irregularities
An inspector from the Federal Aviation Administration (FAA) stated that a certified airframe and powerplant (A&P) mechanic had failed to follow inspection procedures as outlined in the work card and the manufacturer's maintenance manual. This failure was identified as the reason for the worn skid condition that contributed to the accident.