Rather than continuing to hijack the CH 640 thread here >> https://www.homebuiltairplanes.com/forums/threads/vne-limit-on-ch-640.31867/ I think its best to continue this part of the discussion in its own thread. There was quite a mess in the late 1970's when CriCri kits were being produced and sold in North America by Zenair. There was an agreement with the original designer Mr Colomban, but Zenair made many changes to the design in the process of producing the kits. Long story short there was a fatality due to flutter in the modified aileron controls. The CriCri has a mixer for the flapperons and one of the critical parts is a 32mm diameter 2024 aluminium tube that runs under the seat pan. This was changed to a smaller 4130 steel tube, presumably to reduce complexity and speed up the manufacturing time. Turns out to be a terrible idea when someone just uses TLAR instead of actually sitting down and running the numbers.