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Has anyone experienced a slight up / down skin "popping" between rib bays while fitting a lower skin?
I'm about half way complete with pilot drilling the right lower skin and noticed the skin will pop up / down slightly whenever you apply a little pressure to the skin on either side of a rib at the top of the rib arch area. It will slightly pop in one side and pop out the other side flush on a rib bay, you can pop the skin back and forth and even make the skin flat between bays. The skin lays flat and follows the rib contour just fine starting from the rear spar as I worked from the center, forward and outward evenly one hole at a time. The leading edge of the skin is nice and even along the front spar line when clamped down, so, no alignment issues.. Strangest thing, so I stopped.. Am I being too critical? Any suggestions / thoughts would be appreciated.

If the skin is not on the other side the ribs can twist a bit allowing movement. If you are certain everything is square then I would proceed. Once both aft skins are in place things should stiffen up a lot. I didn't notice the oil can effect on mine. but I built mine vertically.

Hi Bill, the upper skin has been installed and upsized.

I also queried Sonex tech support and they have seen it on one of their quick builds and traced it down to a defectively lasered skin. At their request, I fit the other skin and got the same result. They are shipping me two new lower skins!

Awesome, glad you caught it early!