Abstract: An assembly is provided for an engine. This engine assembly includes a fuel system, a sensor and a processing system. The fuel system includes a fuel source, an engine component and a fuel circuit configured to direct fuel from the fuel source to the engine component. The sensor is configured to provide sensor data indicative of a measured parameter of the fuel directed through the fuel circuit from the fuel source to the engine component. The processing system is configured to identify a fuel leak in the fuel system based on the sensor data. The fuel leak is identified when a measured value corresponding to the measured parameter of the fuel is less than an expected value corresponding to an expected parameter for the fuel directed through the fuel circuit from the fuel source to the engine component.

Abstract: A method is provided for operating an aircraft system. During this method, an engine is operated using first fuel provided by a first fuel source. A fuel supply for the engine is switched between the first fuel source and a second fuel source, where the switching of the fuel supply includes shutting down the engine during aircraft flight. The engine is operated using second fuel provided by the second fuel source.