Aircraft vibrations induced by low-frequency unsteady aerodynamic loads affect the comfort of passengers and reduce the airframe fatigue life. In order to attain high and broadband vibration attenuation levels, a Semi-Active Tuned Mass Damper (SATMD) is developed, that exhibits robust vibration control capabilities and requires minimal structural interference. The SATMD consists of a piezoelectric device, connected to an external Resistive-Inductive electrical circuit, and a small auxiliary mass. Simulations and testing of this damper have shown high sensitivity of its performance to: (1) the location of its structural integration and (2) its electromechanical characteristics. The current paper investigates the tailoring of these design parameters on a lab-scale airframe model, aiming at simultaneous control of 3 modes. The numerical results reveal a favorable strategy to tailor the electromechanical properties. The proposed SATMD leads to more than 10dB simultaneous reduction to all targeted modes, highlighting the robustness of the proposed damping device and the importance of the tailoring process.