NTSB Probable Cause

THE PILOT-IN-COMMAND'S IMPROPER APPLICATION OF COLLECTIVE PITCH DURING AN AUTOROTATIVE LANDING RESULTING IN INSUFFICIENT ROTOR RPM AND IN-FLIGHT COLLISION WITH TREES AND THE TERRAIN. CONTRIBUTING TO THE ACCIDENT WAS THE TOTAL LOSS OF ENGINE POWER DUE TO FUEL CONTAMINATION AND INADEQUATE PREFLIGHT PLANNING/PREPARATION.