A method for operating a hybrid-electric propulsion system of an aircraft, the hybrid-electric propulsion system comprising a propulsor, a turbomachine, and an electrical system, the electrical system comprising an electric machine coupled to the turbomachine, the method comprising: operating, by one or more computing devices, the turbomachine such that the turbomachine rotates the propulsor; receiving, by the one or more computing devices, a command to accelerate the turbomachine while operating the turbomachine; providing, by the one or more computing devices, electrical power to the electric machine to add power to the turbomachine, the propulsor, or both in response to the received command to accelerate the turbomachine; increasing, by the one or more computing devices, one or more clearances within the turbomachine using an active clearance control system of the turbomachine in response to the received command to accelerate the turbomachine, substantially simultaneously with the providing, by the one or more computing devices, electrical power to the electric machine; and maintaining, by the one or more computing devices, a fuel flow to a combustion section of the turbomachine substantially constant for an initial time period in response to the received command to accelerate the turbomachine; wherein the increasing, by the one or more computing devices, the one or more clearances within the turbomachine using the active clearance control system comprises increasing, by the one or more computing devices, the one or more clearances within the turbomachine using the active clearance control system substantially simultaneously with the maintaining, by the one or more computing devices, the fuel flow to the combustion section of the turbomachine substantially constant for the initial time period. operating, by one or more computing devices, the turbomachine such that the turbomachine rotates the propulsor; receiving, by the one or more computing devices, a command to accelerate the turbomachine while operating the turbomachine; providing, by the one or more computing devices, electrical power to the electric machine to add power to the turbomachine, the propulsor, or both in response to the received command to accelerate the turbomachine; increasing, by the one or more computing devices, one or more clearances within the turbomachine using an active clearance control system of the turbomachine in response to the received command to accelerate the turbomachine, substantially simultaneously with the providing, by the one or more computing devices, electrical power to the electric machine; and maintaining, by the one or more computing devices, a fuel flow to a combustion section of the turbomachine substantially constant for an initial time period in response to the received command to accelerate the turbomachine; wherein the increasing, by the one or more computing devices, the one or more clearances within the turbomachine using the active clearance control system comprises increasing, by the one or more computing devices, the one or more clearances within the turbomachine using the active clearance control system substantially simultaneously with the maintaining, by the one or more computing devices, the fuel flow to the combustion section of the turbomachine substantially constant for the initial time period.