As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) AFTER CLIMB, WHILE CRUISE SETTINGS WERE BEING ESTABLISHED THE RIGHT HAND PROPELLER SPEED DROPPED TO 1550 RPM AND HELD THERE. FURTHER CORRECTION INITIATED WERE UNABLE TO MOVE THIS SETTING. AFTER AN UNEVENTFUL LANDING, MAINTENANCE DISPATCHED TO THE AIRCRAFT AND REPLACED THE OVERSPEED GOVERNOR ON THE RIGHT HAND ENGINE. THE ENGINES WERE GROUND RUN AND THE SYSTEMS CHECKED SERVICEABLE AND THE AIRCRAFT WAS RETURNED TO SERVICE.