Today, after taking down Christmas lights and tending to Amelia's needs, I headed down to work on the elevators some more. Near the trailing edge of each elevator, and also in the trim tabs, there are bits of high compressive strength foam that get "pro-sealed" to the skins. In order to get a strong bond, you must first prep the skins by scratching off the surface Al-Clad and roughening the metal in that area. Below, you can see the procedure: measure, mark the extent of the surface that receives the adhesive and then use sand-paper to roughen it. It's important to use aluminum oxide sandpaper whenever your sanding aluminum. Silica can react badly.
