A hybrid-electric propulsion system 50 includes a turbomachine 102 and an electric machine 56 coupled to the turbomachine 102. A method for operating the hybrid-electric propulsion system 50 includes receiving information indicative of an operability parameter of the turbomachine 102; determining the turbomachine 102 is operating within a predetermined operability range based at least in part of the received information indicative of the operability parameter of the turbomachine 102; and operating the hybrid electric propulsion system 50 in an electric generation mode to generate electric power with the electric machine 56 in response to determining the turbomachine 102 is operating within the predetermined operability range.