What was found
(CAN) DURING CLIMB, FLT CREW NOTED A FLUCTUATION IN TORQUE & PROP RPM ON NR 1 ENGINE. PROP APPEARED TO BE GOING TO AN UNCOMMANDED FEATHER POSITION. AS A PRECAUTION, SECURED NR 1 ENG IAW SOP. RETURNED FOR LANDING. ACFT & ENG INSPECTED BY MX. ENGINE, PROP & ENGINE CONTROL LINKAGES INSPECTED & CHECKED. ENGINE WIRE HARNESS`S & CONNECTORS INSPECTED & CLEANED. EXTENSIVE GROUND RUNS CARRIED OUT & ALL SYS FUNCTION CHECKS COMPLETED FAULT FREE, NOT ABLE TO DUPLICATE FAULT. ACFT RELEASED FOR A MX CHECK FLT. ALL ENGINE PARAMETERS, SYS & INDICATIONS OPERATED NORMAL. ACFT POSITIONED BACK TO MAIN BASE. AFTER CONSULTATION WITH MFG, INSPECTED THE P3 SYS PLUMBING & LINES. OIL FILTER REMOVED AND INSPECTED, NO CONTAMINATION PRESENT, SEALS ON PROP TRANSFER TUBE WERE REPLACED. WING ROOT WIRING HARNESSES & CONNECTORS FOR NR 1 ENG INSPECTED, CHECKED AND CLEANED. OVERSPEED GOVERNOR REPLACED AS A PRECAUTION & ADDITIONAL GROUND RUNS AND FUNCTION CHECKS CARRIED OUT AND ALL PARAMETERS & INDICATIONS NORMAL.