As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LCQ - MAJOR REPAIR - DURING C-15 CHECK INTERGRANULAR CORROSION WAS FOUND ON UPPER SURFACE OF AFT CABIN FLOORBEAM AT BS 986, LBL 18 TO RBL 44. MAINTENANCE REMOVED FLOORBEAM UPPER TEE CAP AT BS 986, LBL 18 TO RBL 44; FABRICATED A NEW REPLACEMENT TEE CAP; INSTALLED REPAIR PART IAW B737-200 SRM 53-10-09 FIG 2 PG 1.