What was found
DURING ANNUAL INSPECTION, FOUND LEFT WING, TIP RIB WAS NOT RIVETED TO MAIN SPAR. THIS APPEARS TO HAVE NEVER BEEN RIVETED. THIS HAS APPARENTLY BEEN OVERLOOKED SINCE THE AIRCRAFT WAS BUILT IN 1975. THE DEFECT IS PLAINLY VISIBLE WITH THE WING TIP REMOVED, IT IS NOT HIDDEN BEHIND ANY LIP OR FLANGE.