As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING C-05 CHECK A 11/16 INCH CRACK WAS FOUND ON INBOARD SIDE OF SUPPORT CHANNEL LOCATED ON AFT SIDE OF BS 520 FLOORBEAM AT RBL 24.75. MAINTENANCE REMOVED CRACKED SUPPORT CHANNEL AT BS 520. RBL 24.75; FABRICATED A NEW REPLACEMENT CHANNEL PER DWG 66-22187; INSTALLED REPAIR PART IAW B737-300 SRM 51-40-02.