Continuing with the rear wing spars…
…getting all the pieces in place and then updrilling to the final hole size.
Notice on the ends with the thick flanges that the construction is different for each side. One reason is, for simplicity, the Sonex ribs are all the same for both wings. They don’t make left and right ribs with a different direction of bend. The forward facing flanges accommodate this by facing different directions. Also because the wings just cross in the fuselage, one wing is slightly ahead of the other. The attach fitting mounts forward of the channel on one to help accommodate that.