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 A .3125 INCH CRACK WAS FOUND ON FLOOR SUPPORT CHANNEL AT BS 540, RBL 0 TO RBL 25. MAINTENANCE REMOVED CRACKED FLOOR SUPPORT CHANNEL AT BS 540, RBL 0 TO RBL 25; FABRICATED A NEW REPLACEMENT CHANNEL PER DWG 65-52894; INSTALLED REPAIR PART IAW B737-300 SRM 51-40-05 FIG 2, PG 4.