As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MAIN CABIN FLOOR SUPPORT INTERCOSTAL 2 EACH AT LEFT NUMBER 4 DRAIN AND SILL AREA HAD EXFOLIATION CORROSION THROUGHOUT AT FASTENER HOLE LOCATION BODY STATIONS 1640 TO 1682, LEFT BUTTLINE 54. INSTALLED 2 EACH INTERCOSTALS, DRAIN PAN, AND SCUFF PLATES PER SRM 51-40-02.