During the build on N235SP (EARLY LNC2) I noted that the aileron counterbalance extensions of the lower aileron skins was quite flexible. Considering that the lead weights had to be as far forward as possible, it looked like a real good place for aileron flutter to start.

To stiffen the extensions, I installed three half-moon shaped ribs (ends and middle) made of 1/4 inch pre-preg honeycomb sheet. During flight testing, the airplane was dive tested to 10% above red-line (carefully, a few knots at a time) with no hint of "buzz" or flutter onset.

The counterbalances can capture water so be sure to add drain holes anywhere water could accumulate.

Dan Schaefer

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