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 MAIN CABIN FLOORBEAM AT BS 990 UPPER FLANGE IS CORRODED BETWEEN RBL 45-70. CORROSION FOUND TO BE OUT OF LIMITS, CUT OUT DAMAGED AREA. FABRICATED REPAIR PARTS. INSTALLED REPAIR PART, NO OTHER DEFECTS WERE NOTED. AIRCRAFT WAS RETURNED TO SERVICE.