As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING C4 S1 C CHECK INSPECTION NOTED MAIN DECK WEB AT FRAME 70 RBL 52 WAS CORRODED. MAINTENANCE REMOVED AND REPLACED MAIN DECK WEB AT FRAME 70 RBL 52 IN ACCORDANCE WITH THE REQUIREMENTS OF SRM 51-72-11. UPON COMPLETION OF THE REPAIR IT WAS INSPECTED AND FOUND ACCEPTABLE.