Preliminary reliability analysis and impact on aircraft safety of a smart redundant electromechanical actuator, design of a test rig

The purpose of this work is to illustrate the design of a smart scalable electromechanical actuator with a special focus in its use in the flight stabilization system of a helicopter. A reliability and safety study of the sub-system designed to be included in the autopilot system is presented in the first part of this thesis, while in the second part, the design of the first test rig of this actuator is presented in order to validate the design process and the studied architecture. The object of this thesis is to conduct a preliminary reliability and safety study of the system to identify the best configuration for the electromechanical linear actuator developed. The aim is to provide a useful tool for identifying the redundancies needed to meet the safety requirements imposed on a series actuator for flight controls. For these analysis, regulations and official database have been used as reference, such as "Nonelectronic Parts Reliability Data Publication (NPRD) 2016" and "Failure Mode/Mechanism Distributions (FMD) 2016". These data have been used to create spreadsheets for a reliability prediction study and a "Failure Mode, Effects, and Criticality Analysis (FMECA)" of the actuator, as well as a "Fault Tree Analysis" for the identification of multiple failure criticalities. At the current stage of the project, the analysis show that the actuator thus designed meets the safety requirements imposed for use in the primary flight controls of a helicopter. This thesis also presents the first test rig designed to verify the correct functioning of the innovative actuator developed. The purpose of this test rig will be to verify the results obtained in the simulation phase and the behaviour of the system following the injection of specific faults.