As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING INSPECTION, LEVEL 3 CORROSION WAS FOUND ON 4 T FITTINGS INSIDE THE RIGHT WING AILERON. THE PROBABLE CAUSE IS DISSIMILAR MATERIALS (STEEL BOLTS IN ALUMINUM FITTINGS ATTACHED TO A COMPOSITE SPAR). THE FITTINGS WERE REPLACED AT RIBS 4, 11/12, AND 19. REFERENCE ATR 42 SRM 57-61-10 PAGE 115/116. THE TYPE OF CORROSION FOUND WAS EXFOLIATION. THE FITTING PART NUMBERS ARE: S57610025202, S57610025204, AND S57610025200.