Hybrid Kalman filter approach for aircraft engine in-flight diagnostics: Sensor fault detection case

In this paper, a diagnostic system based on a uniquely structured Kalman filter is developed for its application to in-flightfault detection of aircraft engine sensors. The Kalman filter is a hybrid of a nonlinear on-board engine model (OBEM) and piecewise linear models. The utilization of the nonlinear OBEM allows the reference health baseline of the diagnostic system to be updated, through a relatively simple process, to the health condition of degraded engines. Through this health baseline update, the diagnostic effectiveness of the in-flight sensor fault detection system is maintained as the health of the engine degrades over time. The performance of the sensor-fault detection system is evaluated in a simulation environment at several operating conditions during the cruise phase of flight.