Methods and apparatus for operating gas turbine engines

An aircraft gas turbine engine assembly (10), including at least one propelling gas turbine engine (11) comprising a core engine (13) and an exhaust (32). The core engine includes at least one turbine (20) for generating thrust for the aircraft; and at least one auxiliary engine (12) including an inlet (24), at least one turbine (44), and an exhaust (80). The inlet is coupled in flow communication with at least one propelling gas turbine engine, such that a portion of airflow (31) flowing through the propelling engine is extracted from the propelling engine upstream from the propelling engine turbine, and is channeled to the auxiliary engine for generating power.