A computer-implemented method of assessing a health of a gas turbine engine of a hybrid-electric propulsion system for an aircraft includes receiving, by one or more computing devices, data indicative of an amount of electrical power provided to, or extracted from, an electric machine. The method also includes receiving, by the one or more computing devices, data indicative of an operating parameter of the hybrid-electric propulsion system. The method also includes assessing, by the one or more computing devices, a health of the gas turbine engine based at least in part on the received data indicative of the amount of electrical power provided to, or extracted from, the electric machine and the received data indicative of the operating parameter of the hybrid electric propulsion system. The method also includes providing, by the one or more computing devices, information to a user indicative of the health of the gas turbine engine.