As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKEOFF FLUID WAS WITNESSED TREAMING FROM THE LT WING. THE CREW ELECTED TO RETURN TO THE AIRPORT WHERE THE AIRCRAFT LANDED UNEVENTFULLY. MAINTENANCE FOUND THE LT WING RIB 19 FLAPPER VALVE TO BE THE CAUSE OF THE LEAK. THE VALVE WAS REPLACED AND THE DISCREPANCY CLEARED.