As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE COMPLETING AN ANNUAL INSPECTION, REMOVED FUEL CAPS TO INSPECT THE CAPS, SEALS AND ADAPTERS. FOUND THE LEFT WING MAIN TANK FUEL CAP ADAPTER HEAVILY CORRODED AND PITTED. WITH THE EXTENT OF CORROSION ON THE ADAPTER, THE CAP WOULD NOT SEAL ALLOWING WATER TO ENTER THE FUEL BLADDER.