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 HVY CK FOUND CORROSION FOUND ON CENTER FUSELAGE 3 FLOOR STRUCTURE UPPER SHEET AT FR 85-86 LH SIDE. REPLACED UPPER SHEET PN 170-86101-001 IAW SRM 51-41-01, 51-43-01. SEE AAR NRC# 4500907-1000-0066 FOR WORK PERFORMED. AC WAS RTS.