As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE IN HEAVY MAINTENANCE PERFORMING INSPECTION IT WAS NOTED THAT THE NR 1 FUEL TANK UPPER AFT VENT LINE IS CHAFED AT WS 491. FABRICATED DOUBLER FROM 2024-0 .040 INCH DIM 3 X 4.2 INCHES. INSTALLED REPAIR, NO OTHER DEFECTS WERE NOTED. AIRCRAFT WAS RETURNED TO SERVICE.