As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING A C-CHECK INSPECTION, CORROSION WAS FOUND ON LOWER SURFACE OF CENTER WING, CENTER SECTION, WHICH FORMS THE UPPER WALL OF THE RAM AIR DUCT USED FOR COOLING OF THE AIR CONDITION SYSTEM ABOVE LEFT PLENUM CHAMBER ASS AT LBL 20 AND STIFFENER 5. DURING CORROSION REMOVAL THE GROUND OUT EXCEEDED ALLOWABLE LIMITS. REPAIRS ARE BEING ACCOMPLISHED IAW SRM. TAT:42266 TAC: 21515