A system comprising: a gas turbine engine (20;120) comprising a low speed spool and a high speed spool ; a spool coupling system comprising an electro-mechanical actuator and a clutch configured to mechanically link the low speed spool and the high speed spool ; and a controller operable to: determine a mode of operation of the gas turbine engine (20; 120); monitor for a spool coupling activation condition associated with the mode of operation; activate the electro-mechanical actuator of the spool coupling system based on the controller detecting the spool coupling activation condition, wherein engagement of the clutch and power transfer between the low speed spool and the high speed spool occurs based on activation of the electro-mechanical actuator of the spool coupling system and reaching an engagement condition of the clutch of the spool coupling system; and deactivate the electro-mechanical actuator of the spool coupling system after disengagement of the clutch to prevent reengagement of the spool coupling system above the spool coupling activation condition, wherein disengagement of the clutch of the spool coupling system occurs based on the gas turbine engine (20; 120) reaching a disengagement condition of the clutch . a gas turbine engine (20;120) comprising a low speed spool and a high speed spool ; a spool coupling system comprising an electro-mechanical actuator and a clutch configured to mechanically link the low speed spool and the high speed spool ; and a controller operable to: determine a mode of operation of the gas turbine engine (20; 120); monitor for a spool coupling activation condition associated with the mode of operation; activate the electro-mechanical actuator of the spool coupling system based on the controller detecting the spool coupling activation condition, wherein engagement of the clutch and power transfer between the low speed spool and the high speed spool occurs based on activation of the electro-mechanical actuator of the spool coupling system and reaching an engagement condition of the clutch of the spool coupling system; and deactivate the electro-mechanical actuator of the spool coupling system after disengagement of the clutch to prevent reengagement of the spool coupling system above the spool coupling activation condition, wherein disengagement of the clutch of the spool coupling system occurs based on the gas turbine engine (20; 120) reaching a disengagement condition of the clutch . monitor for a spool coupling activation condition associated with the mode of operation; activate the electro-mechanical actuator of the spool coupling system based on the controller detecting the spool coupling activation condition, wherein engagement of the clutch and power transfer between the low speed spool and the high speed spool occurs based on activation of the electro-mechanical actuator of the spool coupling system and reaching an engagement condition of the clutch of the spool coupling system; and deactivate the electro-mechanical actuator of the spool coupling system after disengagement of the clutch to prevent reengagement of the spool coupling system above the spool coupling activation condition, wherein disengagement of the clutch of the spool coupling system occurs based on the gas turbine engine (20; 120) reaching a disengagement condition of the clutch . <EOS>