In the aeronautical sector, safety and reliability represent essential requirements. In this specific case, hydraulic actuators play a critical role in the flight control systems of helicopters. Their proper functioning is therefore crucial to ensure the stability, maneuverability, and safety of the aircraft. For this reason, actuators are subjected to rigorous environmental qualification tests, compliant with international regulations and standards such as RTCA DO-160, which certify their reliability across a wide range of operating conditions, including extreme thermal environments. This thesis work, carried out in collaboration with Microtecnica, aims at the thermo-fluid dynamic study of a climate-controlled box designed for the qualification testing of a Main Rotor Actuator (MRA).