As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT NOTED SMALL WISPS OF SMOKE IN THE COCKPIT AND CO PILOT NOTICED OIL ON THE LEADING EDGE OF THE RH WING. PILOT RETUNED TO AIRPORT AND BROUGHT THE AIRPLANE TO THE MX HANGAR. I NOTICED OIL ON THE RH SIDE OF THE ENGINE COWLING. UPON REMOVING THE UPPER COWLING I FOUND A LOOSE "B" NUT ON THE OIL RETURN LINE FOR CYLINDER #1. I PROPERLY TIGHTENED THE B NUT, TEST RAN THE THE ENGINE AND CHECKED FOR LEAKS. NONE WERE FOUND. I INSTALLED THE UPPER COWL AND RETURNED THE AIRCRAFT TO SERVICE.