As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PAX COMPARTMENT FLOOR STRUCTURE INTERCOSTAL BETWEEN STA 380 AND STA 400 AT BUTT LINE 0 HAS CRACKS AT 4 LOCATIONS ON UPPER SURFACE. GROUNDED - YES. REMOVED AND REPLACED 1EA. PAX COMPARTMENT FLOOR STRUCTURES INTERCOSTAL BTWN STA 380 AND 400, BL0 IAW B737 800 SRM 51 40 02 0G PG 35, FIG 8 AND PG 2 STEP 4.B.