This session started by flipping over the right wing spar so that the top side was up, and then countersinking all of the holes. The fuel tank attach nutplates needed their screwholes countersunk deeply, like the bottom of the spar. Then the two rows of rivet holes along the entire length of the spar needed to also be countersunk for a dimpled skin. Then I treated all of the holes with more Alodine pen solution to prevent corrosion.