I am using the Fatuba S3004's. Yes, it could be the aileron material. It has many lighting holes in them and are not as stong as I would like. I am picking up new stock at the hobby shop to replace them. These are 3" ailerons and I will be putting in 2 inch stock solid. Also I have just moved the elevator & rudder servo's back on the tail of the plane. Replacing all rods with 4-40 ones and try it again. Thanks for the ideas. I have 19 planes and this is the first one that has ever had a flutter problem.