Electromechanical actuator fan failure analysis and safety-critical design

The aim of this study is to use fault tree analysis to gain a better overall understanding of how to improve the reliability of a fan cooling system used to prevent electromechanical actuation systems (EMAs) from overheating. It is critical to manage the waste heat generated by EMAs on aircraft during all flight missions because EMA failure due to overheating could lead to an aircraft catastrophic failure. Heat generation by high-power-density power electronic devices and EMA motors has reached a heat flux density that thermal management of EMA by natural convection is not feasible, forced air cooling is needed. Since EMA motors and power electronic drives must operate at various altitudes and temperature throughout a flight mission, there is a need to develop a variable-speed fan that can operate efficiently and reliably over a wide range of pressure and temperature. To prevent EMAs from overheating and bring EMA failure probability to an acceptable level, a sturdy cooling fan which can operate under variable body forces due to aircraft maneuvering is required.