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-18 CHECK CORROSION WAS FOUND ON UPPER AND LOWER SURFACE OF FLOORBEAM UPPER CHORD AT BS 312, BETWEEN LBL 9 AND RBL 36, WL 208. MAINTENANCE CUT OUT DAMAGE IN FLOORBEAM UPPER CHORD AT BS 312, FROM LBL 9 TO RBL 36; FABRICATED A NEW REPLACEMENT SECTION OF UPPER CHORD AND 2 EACH REPAIR ANGLES; INSTALLED REPAIR PARTS IAW B737-300 SRM 53-10-510 FIG 205.