What was found
LCQ - EES - DURING C-18 CHECK A .75 INCH CRACK WAS FOUND ON CABIN FLOOR SUPPORT CHANNEL AT BS 520, LBL 4. MAINTENANCE REMOVED DAMAGED FLOOR SUPPORT CHANNEL BS 520, LBL 4 - 21; FABRICATED A NEW REPLACEMENT FLOOR SUPPORT CHANNEL; INSTALLED REPAIR PART IAW B737-300 SRM 51-40-02, PG 16-17.