Week 17: Right Wing Tip

This week I finally finished the wing tip installation. I received the new nut-plates, and got them all installed. That process was pretty straightforward using the method I started with the Tinnerman plates.

I used a deburring wheel to remove the coating from the nut-plates that attach the Archer nav antenna so that they have the best possible electrical connection. Then I also used scotch-brite to remove the primer from the wing skin so the rivet heads will be in contact with the inside of the skin. I tired to countersink those rivet holes a little shallower to help ensure good contact there as well. The screws should also provide an electrical connection, but a good ground path to the airframe is critical to the operation of the antenna so I wanted to provide as much contact as possible.

The nut-plates securely fasten the antenna to the wing tip, but I also wanted to keep the tail of the antenna from flopping around. I decided to use VHB tape to secure it to the inside of the tip. This looks like it will work very well.

The last phase of the wing tip installation was the mounting screws on the trailing edge. Aft of the skin, the wing tip fits over the end rib so the captive fasteners had to be installed in the rib instead of in the tip. I decided to use riv-nuts for these instead of nut-plates. I thought this would be easier, but in hind-sight I don't think it was.

My first attempt had a little misalignment with the holes in the wing tip and the riv-nuts, then I tried to install the screws with a cordless drill and managed to break off several screws in the riv-nuts. After briefly attempting to remove the broken screws, I decided to just cut off the riv-nuts with a Dremel and replace them.

After doing that, I used a 6-32 tap to clean up the riv-nut threads and enlarged the holes in the wing tip to all the screws to fit better. I then used a hand screw-driver to install the screws for the final time to keep from breaking any. The only remaining task on the wing tip is to wire up the lights and the antenna. I plan to do that this week, then I can install it for the last time.

In between other tasks I have been prepping parts for the left wing. I have all the rib subassemblies complete and have started prepping the stand-alone ribs. I need to build a wing stand, then I will move the right wing onto it to clear up my tables for the left wing. Before I go too much farther I am also going to start working on the left fuel tank so that the sealant can setup for plenty of time before testing it.