Helicopters are an essential part of both civil and military activities. In the future, it is expected that a significant increase in the use of this mode of transportation widely. There is a need to maintain the cabin in a good and safe condition so that the passengers and the crew inside the cabin feel comfortable. For a cabin to be maintained in comfort conditions, an efficient environmental control system is to be adapted and in case of an aircraft, cabin pressure control system (CPCS) is needed to depressurize the cabin and maintain constant cabin pressure. Helicopter heat loads are challenging because of their design i.e., more transparent surfaces, heat from the engine (generally mounted on the ceiling) and infiltration effect. Heat load on the cabin must be mitigated through an efficient air cycle system. In this project, helicopter cabin heat load values and mass flow of air required at different altitudes are determined and a heat exchanger for an environmental con