I'm going to mount the servo on a .032" doubler on the inside of the left rudder skin. I'll make a door on the right side, to access the servo. (The idea is to keep from having a bunch of screws on one side of the rudder. I just like a more organized look).
So I built the doubler, match drilled the skin, made the pushrod exit hole, countersunk the back of the servo mounting plate, and test fit the servo.
