In the scope of the development of a more electrical aircraft, this subject aims at the development and the experimental validation of a reliable sizing method for mechanical transmission elements, specifically screw drives and thrust bearings of aeronautic flight control actuation system. In fact the replacement of the hydraulic with electric devices promises many advantages but we have to pay attention to the compliance with the operational reliability and safety requirements of these essential components.Main critical requirements for the sizing method of rolling drivetrain contact elements are related to oscillation loads and reversal of the direction of load, low frequencies oscillating movements, proper lubrication conditions at critical temperatures (low and extreme high temperatures). These critical issues are typical of aeronautic applications, specifically of the helicopter swashplate actuation system, and they are not covered by the standard norms.At first, the project activities will concern a deep survey of state of the art, including norms, patents and proprietary methods of sizing. Moreover a targeted analysis to the exact definition of the operating conditions will be conducted. These first steps will be essential steps for the development of the sizing method. Then, the third step will be the analysis of the stress at the contact area between the balls/rollers and the tracks on both bearings and screws in dynamic conditions that will be performed by dedicated software.The case of the helicopter swashplate will be consider as a benchmark and a dedicated sets of rolling contact thrust bearing and balls screws transmission will be designed, manufactured and tested in order to validate the developed new method of sizing.