Abstract: A turbofan gas turbine propulsion engine includes a system to transfer power from the low pressure turbine to the high pressure turbine and/or extract additional load from the low pressure turbine during certain turbofan engine operational conditions. The systems include a hydrostatic power transfer system that includes a hydraulic pump and a hydraulic motor coupled to the low pressure and high pressure turbine, respectively. The systems additionally include a mechanical and electrical load shifting/loading sharing systems that use clutches and gear assemblies to share and/or shift load between the turbines.

Abstract: The present invention provides a relatively simple way to automatically turn on and off the fuel to a starter/generator cooling system during engine start. The present invention takes advantage of a fuel pressure rise provided by an engine fuel boost pump during the period from engine start to engine idle conditions. This pressure rise is used to stroke a shutoff valve in a fuel return to tank valve (FRTTV), which shuts off the starter generator cooling fuel flow. This shutoff occurs automatically with no other external input from, for example, an engine controller. A check valve is also included that prevents back flow through the FRTTV in the event of an engine start with no aircraft pumps running.

Abstract: A bleed air power assist system is coupled to a gas turbine engine that includes a high pressure turbine, a low pressure turbine, and an electrical generator driven by the high pressure turbine. The bleed air power assist system selectively bleeds air discharged from the high pressure turbine and supplies it to an air turbine that is also coupled to the generator. Thus, the system selectively reduces the power extracted from the high pressure turbine. This, coupled with the bleed air that is diverted from the low pressure turbine, allows the low pressure spool to run at lower speeds when high engine thrust is not needed or desired, but when the generator is still needed to supply high electrical loads.