A propulsion system for an aircraft includes a propeller assembly, a controller, and a pump system. The propeller assembly includes a propeller and a power system, the power system including an electric motor and a motor converter. The controller is connected to the power system and configured to switch the power system into a power-off arrangement in response to a temperature of the motor converter being greater than a threshold temperature. The pump system includes a pump and a coolant circuit that cools the motor converter. The pump is coupled to the propeller and to the motor such that rotation of either drives the pump.