The Garmin GAP-26 pitot tube comes without screws. Those #6-32 screws are the same that hold the old 3.5″ hard disks in your PC. So you might have some.
After the bottom skin is attached and riveted, the cables for the wing tip and the Pitot tube need to be inserted.
Installing the bottom skin is easy when everything is straight. Initially I’m using rivets and no clecos to position the skins. Rivets have a better fit in the holes and let the skin move a bit so all the holes lign up better. After that process every other hole gets a cleco.
The last 3.2mm rivet above the aileron bellcrank assembly has not enough depth for a 3.2x8mm rivet. A 3.2x4mm rivet fits, if you have one left over from the tanks.
Countersinking these holes in the main spar takes some time and effort. Since I did prepare all center ribs in parallel with the ribs from the right wing, it took just a few hours to rivet the center ribs. It’s agood idea to insert the aileron push rod and the flap torque tube before the ribs make it impossible. Before you rivet any ribs, the wing jigs should be adjusted to be level.