US Patent 7219499 Methods and apparatus for operating gas turbine engines

A method facilitates assembling a gas turbine engine assembly. The method comprises providing at least one propelling gas turbine engine that includes a core engine including at least one turbine. The method also comprises coupling an auxiliary engine to the propelling gas turbine engine such that during operation of the propelling gas turbine engine, at least a portion of the airflow entering the propelling gas turbine engine is extracted from the propelling gas turbine engine upstream from the core engine turbine, and channeled to the auxiliary engine for generating power.