As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT DEPARTED SDF, FUEL WAS VENTING FROM WING SINGLE POINT VENTS. AIRCRAFT REURNED TO SDF. FOUND SINGLE POINT MASTER SWITCH WAS TURND OFF BEFORE VENT SWITCHES WERE CLOSED ISOLATING VENTS IN OPEN POSITION. TURNED MASTER TO 'ON' AND VENT VALVES CLOSED.