What was found
DURING A SCHEDULED INSPECTION, LT ATTACH ANGLE, PN 6420-66340-105, WAS FOUND CRACKED AT STA 767.8 LBL 5.5, WL 177.1. THE CRACK ORIGINATED AT THE BOTTOM HUCK FASTENER AND TRAVELED DOWN TO THE EDGE OF THE ANGLE. THESE ANGLES ATTACH THE INTERCOSTALS TO THE CANTED WEB AT THE ABOVE-LISTED LOCATIONS. PROBABLE CAUSE IS FATIGUE. RECOMMENDATIONS TO PREVENT RECURRENCE, USE 7078-T6, .063 EXTRUSION, RATHER THAN ORIGINAL MATERIAL 7075-T6, .050 INCH BENT SHEET.