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In this paper, small-scaled blade prototypes with the flap-driving mechanism, called SNUF (Seoul National University Flap), were manufactured, and tested in order to realize vibratory load reduction in the rotor system. It was achieved by an active trailing-edge flap which is based on piezoelectric actuator. However, it turned out that the target value of the flap deflection angle was not accomplished in the previous designs. Therefore, the flap driving mechanism needs to be amended. Thus, a new piezoelectric actuator was selected to achieve the target deflection by considering the nonlinear relationship between flap deflection angle and the moment arm length. Re-selection of the actuator required increase of the blade inner space and its size. Therefore, it was required to validate the cross-sectional design of the improved blade configuration. So as to verify the structural integrity, crosssectional analysis was conducted by using UM/VABS. After achieving a satisfactory result of the non-rotating static test of the new flap-driving mechanism, a prototype blade will be manufactured and tested in the whirl tower.