This paper presents a study on the thermal behavior of an electro-hydrostatic servo actuator designed to actuate the ailerons of an airliner. The considered servo actuator was designed using existing commercial off-the-shelf components (electric motor, pump, hydraulic cylinder, valves, hydro-accumulator), and the control part was tuned using numerical simulations performed in SIMCENTER/AMESIM. This study begins with the functional parameters of the components used in the design and uses numerical simulations to test the thermal behavior of the components. A continuous stress spectrum of the servo actuator is considered, with the servo actuator located in a compartment inside the wing. Different external conditions are also considered, such as situations where component wear occurs and component efficiencies deteriorate, thus producing more heat in the system. Based on the energy losses identified, the average efficiency of the studied servo actuator is also evaluated.