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-05 CHECK CORROSION WAS FOUND ON UPPER AND LOWER SURFACE OF FLOORBEAM UPPER CHORD AT BS 986, BETWEEN LBL 3 AND LBL 40. MAINTENANCE REMOVED CORRODED SECTION OF FLOORBEAM UPPER CHORD AT BS 986, FROM LBL 3 TO LBL 40; FABRICATED A NEW REPLACEMENT SECTION OF FLOORBEAM UPPER CHORD; INSTALLED REPAIR PART IAW B737-300 SRM 53-60-51, FIG. 202.