What was found
DURING FLIGHT CABIN AND COCKPIT HAD EXCESSIVE GAS FUMES. PILOT REPORTED FAILED FIRST START ATTEMPT. SECOND START WAS SUCCESSFUL PRIOR TO DEPARTING FOR SCHEDULED FLIGHT. UPON RETURN NOTED PRESENCE OF RESIDUAL FUEL ON AFT ENGINE COWLING, CLAMSHELL DOOR, AND R/H AIRFRAME BODY. INSPECTED DRAIN PIPE OF THE DRAIN TANK FOR OBSTRUCTIONS AND NOTED MINOR OBSTRUCTION. CLEARED OBSTRUCTION AND RECONNECTED. INSPECTED AIRFRAME EQUIPMENT PLATES FOR LEAKAGE. NO LEAKS NOTED. INSPECTED ENGINE FUEL AND FUEL DRAIN COMPONENTS FOR LEAKAGE. NO LEAKS NOTED. CLEANED RESIDUAL FUEL FROM AIRFRAME AND AIRFRAME DRAINS. PERFROMED GROUND RUN WITH NO DEFECTS NOTED AT THIS TIME.