Turboshaft engine clutch configuration

A method of operating a gas turbine engine having an open rotor assembly and a turbomachine including a core, the open rotor assembly including an array of unducted rotor blades and an array of unducted guide vanes, the method comprising:

• operating the gas turbine engine within an engine start condition;
• disengaging an engine clutch disposed between a low speed spool and the open rotor assembly of the gas turbine engine in response to the engine start condition;
• engaging an inter-spool clutch disposed between the low speed spool and a high speed spool of the gas turbine engine in response to the engine start condition;
• applying electrical power to an electric machine, wherein the electric machine is mechanically coupled to the low speed spool through an accessory gearbox, to rotate the low speed spool during the engine start condition;
• sending power to an accessory system via the low speed spool when the engine clutch is disengaged, wherein the accessory system is mechanically coupled to the accessory gearbox;
• operating the gas turbine engine in a post-landing condition subsequent to operating the gas turbine engine in the engine start condition;
• disengaging the engine clutch and the inter-spool clutch during the post-landing condition;
• with the engine clutch and the inter-spool clutch disengaged during the post-landing condition, decoupling the low speed spool and the open rotor assembly so that the low speed spool rotates freely relative to the open rotor assembly and the open rotor assembly stops rotating;
• and
• generating electrical power via the electric machine during the post-landing condition.