As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MCN - DURING C20 CHECK DISCOVERED CORROSION ON THE AFT CARGO FLOOR WEB AT BS 858 TO BS 863, BL 19R AND WL 158. CORROSION WAS FOUND TO BE OUT OF LIMITS IAW BOEING 737-300 SRM 53-60-15-OI 1 FIG 1. MAINTENANCE REMOVED WEB AND INSTALLED NEW WEB AT BS 858 TO BS 863, BL 19R AND WL 158 IAW BOEING 737-300 SRM 51-40-02-0G.