As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) PILOT WAS IN CRUISE FLIGHT & SET UP FOR HIS APPROACH FOR LANDING AND THE ENGINE DECELLED BACK TO IDLE.THE ROTOR RPM DECAYED AND HE ENTERED AN AUTOROTATION AND LANDED WITHOUT FURTHER INCEDENT. WHEN ON THE GROUND WE TRIED TO MOVE THE THROTTLE TO FULL OPEN AND THE ENGINE WOULD ALMOST QUIT.THE GOVERNOR WAS CHANGED AND THE AIRCRAFT OPERATED NORMALLY.