What was found
(CAN) IN CRUISE, PRIOR TO DESCENT, AUDIBLE AND INDICATED. PROP SURGE AND RPM DECREASE OF APPROXIMATELY 200 RPM OCCURRED. PROP PITCH WAS ADJUSTED TO FULL FINE POSITION. NO RESPONSE TO BLADE CHANGE WAS NOTED. DURING DESCENT PRIOR TO APPROACH, PROP SLOWLY INCREASED PITCH APPROXIMATELY 100 RPM. APPROACH WAS CONTINUED AND LANDING WAS COMPLETED SUCCESSFULLY. MAINTENANCE INSPECTION REVEALED ENGINE OIL LEAKING FROM PROP GREASE FITTINGS. AN INTERNAL HUB SEAL LEAK WAS DETERMINED AND CONFIRMED BY PROP OVERHAUL FACILITY. PROP REMOVED.