What was found
DURING ACCOMPLISHMENT OF SB A320-57-1155, REV 3, CORROSION WAS DETECTED ON THE LOWER SURFACE OF THE LT WING TOP SKIN PANEL. AREA BLENDED IAW SRM 57-21-11. HFEC INSPECTION PERFORMED, REVEALING NO CRACK INDICATIONS. REPAIRED IAW EC 5720.000004. REPAIR CLASSIFIED AS MAJOR .