Wing Top Skins Riveting

Last weekend I riveted the upper skins on the left wing. As I did when clecoing the skins in place, I started riveting onto the strongest parts first (4mm rivets into the main spar cap), then ribs, then stringers.

When pulling these blind rivets, it leaves an open hole that should be filled in. I borrowed an idea from Craig Maiman, who in turned got his idea from Kit Planes magazine, to use a light-weight spackle to fill in the rivets. I bought some from a local Sherwin Williams store, and filled a syringe with the material and then injected it into the rivet cavities. It comes out in a creamy/pasty consistency, and then hardens relatively quickly (within an hour) so that it can be sanded smooth.

Short GIF video of filling the cavity – almost like dental work!

I wanted to add the step skins next, but I found an issue with fit of the skin. Specifically, the holes in the top step skin (WG-SKN-003-L-C-) did not line up with the bottom skin & ribs. My assumption was that the skin was bent incorrectly, which was confirmed by TAF technical support. This skin is pretty thick material, so there’s no way I can fix this myself – and besides, aluminum doesn’t like to be re-bent. I thought about drilling new holes, but because the mis-alignment is about 2.5mm, and the holes are 3.2mm in diameter, I would wind up creating a slot instead, and the rivet possibly could pop out over time. Instead, TAF will be sending me a replacement skin.

The bend of the upper step skin tucks between the lower skin and the ribs (which is what this lower skin is attached to with clecos in this pic). But because the holes in the top skin are misaligned in the red circled area, I can’t get any clecos in there.
The red lines help illustrate the misalignment here between the upper and lower step skins (the lower step skin is the correct one)
Pretty clear to see the misalignment in this pic. The red circle is where the rivet hole is on the step skin rib.

Since I had this issue with the left step skin, I decided to check the right side skin, but that one looks to be OK.

While I wait for a new step skin, I’m going to build the ailerons & flaps, and then get started on building the right wing.

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