I learned the hard way on my RV-4, that it is a good idea to use some RTV between the aft portion of the skin stiffeners. The little blob of RTV keeps the skin from flexing right at the tip of the stiffener leading to small cracks at the trailing edge of your rudder. Cracks at the trailing edge then need to be stop drilled. The stop drilled cracks make people looking at your airplane talk badly about you. By the way, if you do this on your rudder, make sure you use the non-acidic type of RTV.
