Amethod for troubleshooting soft failure of aircraft engine sensor was proposed based on Kalman filters and sequential probability ratio test(SPRT). This approach was used to process Kalman filter residuals and detect the soft sensor failure with revised SPRT.Thereafter

this method was compared with WSSR (Weighted Sum of Squared Residual) in troubleshooting soft failure of sensors.The simulation results show that SPRTmethod is more suitable to detect soft failures of aircraft engine sensor.