The pilot’s use of an improper clutch engagement procedure, which resulted in clutch glazing, slippage, and, ultimately, the in-flight disengagement of the clutch and a loss of rotor rpm. Contributing to the accident were the installation of a light-weight clutch assembly and a higher horsepower engine, both of which increased the tendency for clutch slippage, and inadequate inspection of the clutch assembly.

PARTIAL LOSS OF ENGINE POWER DUE TO UNDETERMINED REASONS AND UNSUITABLE TERRAIN ENCOUNTERED DURING THE AUTOROTATIVE LANDING.

FAILURE OF THE PILOT TO MAINTAIN ROTOR RPM AFTER PULLING UP FROM A SWATH RUN. A RELATED FACTOR WAS THE PRESENCE OF TREES.