What was found
DURING INSPECTION, LEVEL 2 CORROSION WAS FOUND ON THE (T- FITTINGS) ATTACHING THE RIBS TO THE SPAR. THE FITTINGS AFFECTED ARE LOCATED AT THE IB, CENTER, AND OB HINGE FITTINGS. THE PROBABLE CAUSE IS DISSIMILAR MATERIALS (STEEL BOLTS IN ALUMINUM ALLOYED FITTINGS). THE FITTINGS WERE REPLACED AT RIBS 4, 11/12, AND 19. REFERENCE ATR42 SRM 57-61-10 FIG 101.