International audienceThe design of aerospace actuation systems is an exciting challenge in terms of integration and performance requirements, engineering specializations, technological limits and numerical tools. The investigation of future flight control actuation system technologies and architectures has to evaluate the impact of new concepts on each subsystem in a tightly coupled manner. This paper presents an investigation of the effect of control surface splitting on an aileron using a Multidisciplinary System Design Optimization technique. The investigation is then extended to a primary flight control actuation system. Parametric sizing models help determine geometries and performances of rotary on hinge electromechanical actuator, associated power electronics and structural analysis. Promising preliminary results about effects of control surface splitting on aileron and on primary flight control surface layout are presented