As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS IN BASE MAINTENANCE. LEFT OVERWING FILL PORT FAILS BONDING RESISTANCE CHECK. UPON REMOVAL OF THE LEFT OVERWING FILL-PORT FITTING CORROSION WAS DISCOVERED ON THE UPPER AND LOWER SURFACES OF THE FILL-PORT LANDING ON THE WING SKIN. REPAIRED SKIN PER EA 277838.