Incident Overview
A helicopter conducting a sightseeing flight with five passengers aboard experienced a hard landing that resulted in the skids collapsing and the helicopter rolling over.
Sequence of Events
According to the pilot's report, during the final approach turn the airspeed was 35 knots. The pilot encountered a high rate of descent and noticed a split tachometer indication. In response, the pilot initiated an autorotation, but stated that the maneuver was outside the envelope for a safe recovery.
Post-Accident Examination
Examination of the helicopter revealed metal flecks in the freewheeling sprag assembly. The assembly was found to contain very little oil, but there was no evidence of slippage.
Conclusion
The accident sequence involved the pilot turning onto final approach with 35 knots of airspeed, encountering a high rate of descent, initiating an autorotation after noting a split tachometer, and subsequently making a hard landing that caused the skids to collapse and the helicopter to roll over.