US Patent 10961915 Systems and methods for starting an engine

A system for starting a gas turbine engine includes a rotor drive system and a hydraulic motor system operatively connected to the rotor drive system. A gas turbine engine is operatively connected to the hydraulic motor system for starting the gas turbine engine. A method for starting an engine includes initiating single-engine-operation on a multi-engine aircraft. Single-engine operation includes operating a first engine and powering down a second engine. The method includes running a hydraulic motor system. The hydraulic motor system is driven by the rotor drive system and is operatively connected to the second engine. The method includes identifying a need to start the second engine and starting the second engine using the hydraulic motor system.