Although testing tanks needs to be done, it’s not like actually doing some work. I finally got around to putting things away and starting on the main spar. The first step is not shown here, but you have to use the spar predrilled holes as a pattern to drill the wing J channel stock. Pretty straight forward if you pay attention to the instructions.

Then you have to countersink all of the predrilled holes, and there are a lot of them.  Plus, some of them are quite large. When they are done, you have to add a bunch of nut plates that will hold the tanks to the spars and also anchor the wing access panels.