What was found
APPROXIMATELY 40 MINUTES INTO A FLIGHT FROM CLARKSBURG, WV (KCKB) TO ST. MARY'S COUNTY, MD (2W6), OIL WAS OBSERVED ON THE RIGHT ENGINE NACELLE STARTING AT THE VENT ON TOP OF THE NACELLE AND EXTENDING BACK TO THE TRAILING EDGE. AS A PRECAUTIONARY MEASURE, THE PILOT SHUT THE RIGHT ENGINE DOWN AND FEATHERED THE PROPELLER. ATC WAS CONTACTED AND THE REQUEST WAS GRANTED TO TURN BACK AND LAND AT STAFFORD REGIONAL AIRPORT (KRMN). MAINTENANCE FOUND THAT THE RIGHT ENGINE VACUUM PUMP WAS LOOSE. NEW STAR WASHERS WERE INSTALLED AND THE VACUUM PUMP STUDS WERE RE-TORQUED TO PROPER VALUES. THE ENGINE WAS THEN RAN UP AND THE OIL LEAK WAS CORRECTED. IN CONCLUSION, IT WAS DISCOVERED THAT THE GASKET IN THE VACUUM PUMP ON THE