AIRCRAFT ENVIRONMENTAL CONDITIONING SYSTEM AND METHOD

An aircraft environmental conditioning system (100) is disclosed that includes an air cycle machine for conditioning an airflow comprising hot compressed air by reducing its temperature and pressure. The air cycle machine is disposed in a housing (105) in an unpressurized area of the aircraft, and produces conditioned pressurized air in a conduit for delivery to a pressurized area of the aircraft. The system also includes a smoke sensor (152,154) disposed within the conduit (145) or within the housing (105) external to the conduit (145), and a controller (160) in communication with the smoke sensor (152,154) that is configured to respond to smoke detected by the smoke sensor (152,154).