Riveted the top cowl to the piano hinges and the cowl doors to the piano hinges. �wn the middle is a line of rivets that is a “U” channel stiffener for the top cowl. I did screw up in a big way…. I had the top cowl all perfectly flush riveted to the piano hinges and then ding… ding… ding I realized I forgot to attach the “U” channel to the bottom of the piano hinge. � I had to drill out the rivets and redo the riveting. �uff happens