As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE AC WAS IN FOR HEAVY CHECK FOUND CENTER FUSELAGE 3 PAX CABIN FLOOR STRUCTURE CORROSION FOUND AT RT SHEAR PANEL BTW FR 87-88 AND BTW RBL 12" TO RBL 36" AREA. MX REMOVED AND REPLACED RT SHEAR PANEL PN 170-91919-001 BTW FR 87-88 AND BTW RBL 12" TO RBL 36" AREA. IAW SRM 51-42-03. SEE NRC # 4000319-2000-0049 FOR WORK PERFORMED. AC RETURNED TO SERVICE .