Structural Health Monitoring of Electromechanical Actuators in Aviation - Challenges Ahead and Case Study

Electrical actuation concept fits perfectly with the worldwide strategy of more electric aircraft to reduce carbon footprint. However, the integration of linear electromechanical actuators is promising yet challenging in safety critical systems due to the jamming of the driven load. That fault is a critical mechanical transmission failure giving rise to concern in many applications such as primary flight controls or landing gears extension and steering. This paper critically reviews electric actuation solutions currently available for aerospace application, the limits for their upcoming deployment and the different solutions to achieve an on-condition maintenance to reduce any safety risk during lifetime. A particular attention is given to the jamming and possible strategies to avoid any hazard induced by this failure. The most promising approach relies on the establishment of a predictive maintenance by monitoring continuously the actuator to timely warn any structural alteration which is prone to induce jamming. Finally, a case study is presented, showing the ability of engine current monitoring to warn any alteration in the load maneuvering. The current spectrum analysis is found to be sensitive to both mechanical fault and control failure or malfunctioning. On top of that, no addition sensors are needed, making this technique affordable and cost-effective.