What was found
(CAN) PROPELLER RPM DECAYED TO UNCOMMANDED FEATHER AT 1000` AGL AFTER TAKE OFF. PROPELLER FAILURE OCCURRED AFTER THE POST TAKE OFF POWER REDUCTION. UNABLE TO RECOVER PROPELLER TO NORMAL RPM. PRIOR TO THE FAILURE, THE PROPELLER GOVERNOR HAD BEEN REINSTALLED AFTER OVERHAUL. SUBSEQUENT TO THE FAILURE, THE GOVERNOR WAS REMOVED AND A NEW SPEEDER SPRING WAS INSTALLED. GOVERNOR CHECKED FOR COMPLIANCE IN TEST CELL. GOVERNOR REINSTALLED AND GROUND CHECKED FUNCTIONALLY ACCURATE. AIRCRAFT SUBJECT TO A CHECK FLIGHT WITH NO FAULTS FOUND. AIRCRAFT RETURNED TO SERVICE.