As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE IN HEAVY MAINT CHECK * MAJOR * FOUND CORROSION AFT CARGO INTERNAL DOUBLER FOR DRAIN MAST AT FR 86-87 STR 26R-28R. REMOVED AND REPLACED INTERNAL DOUBLER FOR AFT DRAIN MAST IAW SRM 51-40-08. ACFT REMAINS IN HEAVY CHECK UNTIL COMPLETION.