What was found
CREW REPORTED SENSING A STRONG ODOR OF FUEL IN CABIN ON THE RETURN LEG TO THE BASE FOLLOWING A REFUELING STOP. ON LANDING AT BASE THE ODOR HAD DISSIPATED. INSPECTED BEHIND THE INTERIOR WALLS IN THE AREA OF THE FUEL VENT TANK AND SHUT OFF VALVES FOR THE FUEL ODOR WITH NONE NOTED. FOUND NO FUEL LEAKS FROM THE VENT LINES, BELLY DRAIN HOLES, OR SUMPS. OPENED AFT BELLY PANEL & FOUND FUEL WETNESS AROUND ATTACHMENT SCREWS. FOUND FUEL LEAKAGE ON UNDERSIDE OF AFT BELLY PANEL AND IN CAVITY UNDERNEATH. CLEANED AREA THOUROUGHLY. A DRY ROTTED FUEL CAP O-RING WAS REPLACED AND FUEL CAP CHECKED FOR PROPER FIT.