What was found
LOWER WING SKIN FOUND CRACKED AT ANNUAL INSP. (PN 62086-01). UPON DRILLING TO PREPARE A SURFACE PATCH, ABNORMAL SOUND OF SHEETMETAL BREAKING WAS OBSERVED. FURTHER INSP REVEALED THE 2 STIFFENERS ATTACHED TO THIS LOWER SKIN WERE BADLY CRACKED AT WING BUTT AND OPPOSITE END. AFTER AN INSP PANEL WAS INSTALLED IN THIS AREA FOR ACCESS, TOP SKIN PN 62061-02 WING WALK SKIN WAS FOUND CRACKED. UPON REMOVAL OF THIS SKIN, CRACKS WERE BELIEVED TO BE DUE TO CORROSION. RECOMMEND EXTENSIVE INSP IF CRACKS ARE FOUND.