As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING SCHEDULED MAINTENANCE THE LEFT PRESSURE FLOOR SILL FROM FS424.0 TO 449.85 HAD AREAS OF CORROSION AROUND FASTENER NUT PLATES. THE AIRCRAFT WAS INSPECTED AND REPAIRED USING AIRCRAFT MAINTENANCE MANUALS. AIRCRAFT WAS RELEASED FOR SERVICE.