In this session I was just working on scuffing all of the internal parts for the fuel tanks. It's necessary to roughen up the surfaces in order to prepare them for better adhesion of the fuel tank sealant.
Then I also needed to countersink the holes in the fuel tank filler cap flanges so that when they are riveted to the underside of the fuel tank skins, they will be able to sit flush. The new material exposed during the countersunking was then treated by an Alodine pen to prevent future corrosion.