As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CORROSION LT W/W LT KEEL BEAM HAS CORROSION AT SURROUNDING AREAS OF NUT PLATES FROM BS 674 BS 727 WL 148 (LOWER SURFACE OF LOWER CHORD). REMOVED NUT PLATES BLENDED CORROSION. DAMAGE ALL WITHIN LIMITS. REFINISHED SURFACES AND REPLACED NUT PLATES PER B737 400 SRM 53 60 12.