Hey guys, I just got done taking a close look at a complete kit set of ribs and I think you have both discovered that R2 is in fact thinner at the trailing edge (aileron hinge line) than the surrounding ribs. From what I can tell the error is roughly 1/16th or less both sides. This is actually amazing to me as the Hybrid has been in production since fall of 2003 and I've lost count on how many have been built by customers. Nobody has ever reported an issue in building or flying in this regard. Again, I think Crash makes the most important statement in that the ribs need to be parallel to the board at all times for the wing to remain symetrical. I did check the centerlines of the ribs and they are completely symetrical so there is no problem there. With R2 slightly thinner then yes it will appear that the wing will slightly thicken at R3. This is absolutely no issue and obviously no problems with flight performance. Heck, it could even be a positive thing. If you add some balsa to R2 then make sure you do it symetrically to avoid warping the wing. Follow the instruction tip and measure the leading and trailing edge centerlines to assure the ribs are parallel to the board. Hope this helps!