As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MAIN CABIN FLOOR STRUCTURE STA 324 BL0 TO RBL 52 FLOORBEAM UPPER CHORD CORRODED. MAIN CABIN FLOORBEAM UPPER CHORD EXFOLIATED WITH 80 PERCENT MATERIAL LOSS. CUT AND REMOVED FLOORBEAM, FABRICATED NEW CHORD AND REPAIR STRAPS AND INSTALLED IAW B 757 SRM 53-10-08.