As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MCN - MAJOR REPAIR - DURING C-17 CHECK EXFOLIATION CORROSION WAS FOUND ON UPPER SURFACE OF FLOOR SUPPORT (INTERCOSTAL) BETWEEN BS 986.6 AND BS 1006, RBL 33, AT LOCATION OF RT AFT LAVATORY OUTBOARD FORWARD MOUNT. MAINTENANCE REMOVED DAMAGED INTERCOSTAL BETWEEN BS 986.6 AND BS 1006, RBL 33. FABRICATED A NEW INTERCOSTAL AND INSTALLED REPAIR IAW B737-300 SRM 51-40-02 PG 11-12.