Week 13: Fuel Tank Disassembly / Wing Tip
Now that I confirmed the fuel tank is leaking into the inaccessible nose area, the next step was to open it back up so I could get it properly sealed. First I drilled out all the necessary rivets, then used a paint scraper to break the sealant bond between the parts. I had to hammer the scraper through the sealant, and had a couple of places where it decided to go through the tank instead. While I could probably seal the punctures with sealant, I decided I would rather replace the parts. I have ordered the replacements and I will move on to other things until I get them.
I have a few other things besides the fuel tank to complete for the right wing. The last rib had to wait until after the twist jig was removed, which I can do now that the skins are riveted. When attaching the twist jig on the outboard end of the wing, I was not sure if the clecos should be installed on the inside or outside. I put them on the inside, but I think the outside would have been a better choice. To get them removed I had to cut an access hole in the jig. Once I did this it was relatively easy.
With the jig removed from the end of the wing I did a quick fit test of the rib and the wing tip. It's fun to see the wings final shape for the first time.
The other step that was on hold until the jig was removed was the rear spar skin support. The angle that attaches the outboard rib to the rear spar could not be installed until after the jig was removed, and I decided it would be difficult to rivet this angle if the skin support was already attached. This was not in the plans, but I think it was the right decision.
When I first clecoed on the skin support I noticed the angles were significantly off from the parts they attach to. I first started to try and get it closer with a hand seamer, then eventually switch to just hand bending the top angle to match the skin. Maybe this would have been somewhat self-correcting, but I am really happy with the result once the parts were riveted.
The last step for this week was attaching the last rib. I drilled an additional hole for the NAV Antenna wire, then pulled all the wires through and riveting it in place. The next steps for the right wing are to fit the wing tip and install the taxi/landing lights and the nav lights on the tip. I ordered #8 nut plates and machine screws to attach the wing tip, but these seem excessively large so I think I may go with #6 instead.