Incident Summary
A helicopter sustained a hard landing during an autorotation landing. The pilot reported that he could not control the engine RPM using the RPM switch on the collective or the manual throttle control. The N2 tended to exceed 100 percent.
Sequence of Events
The pilot notified his company of the issue and planned an autorotation landing on a grass strip. He stated that he rolled off the throttle at 2100 feet above ground level (AGL) while at 110 knots. At approximately 10 feet AGL, with full right pedal applied, the aircraft continued yawing left and impacted the ground.
Investigation Findings
The operator suspected a high side governor failure as the cause of the pilot's inability to control N2 RPM. However, a post-accident inspection failed to reveal any malfunctions. The aircraft was subsequently repaired and returned to service.