As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE IN HEAVY CHECK MAINTENANCE FOUND CABIN FLOOR STRUCTURE FR90 WITH CORROSION AROUND FASTENER HOLE RBL 26. MAINTENANCE REMOVED CORROSION AND FOUND THE REMAINING THICKNESS TO BE OUT OF LIMITS IAW SRM 51-75-16. REMOVED AND REPLACED FLOOR STRUCTURE PLATE PN-170-60259-001 IAW SRM 53-30-10 AND SRM 51-40-08. A/C REMAINS IN HEAVY CHECK.