As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING A HEAVY MAINTENANCE CHECK, THE CENTER WING BOX LT SIDE UPPER SKIN WAS FOUND TO BE CORRODED OUT OF LIMITS RBL 705 BETWEEN S21C AND S18C. REMOVED CORROSION AND REPAIRED CENTER WING BOX UPPER SKIN IAW AMS AND SCA ENGINEERING ORDERS USING ACCEPTED METHODOLOGY.