Real time performance monitoring of gas turbine engines

A real-time gas turbine engine monitoring system is disclosed which includes a digital processor that utilizes a set of scalar coefficients and the current value of various engine operating parameters to predict the current value of a set of engine performance parameters. The actual values of these performance parameters are monitored and compared with the predicted values to supply deviation or error signals to monitoring logic which provides an indication of faults within the digital processor, within the sensor units which provide the actual values of the monitored performance parameters and within the gas turbine engine. In addition, the deviation signals are utilized within the digital processor unit to determine a time dependent quadratic estimate of the temporal characteristics of each monitored engine parameter. Signals representative of this quadratic estimate are supplied to trending logic that provides prognostic information. To adapt the disclosed engine monitoring system to the particular engine being monitored, the system is operable in a calibration mode wherein digital filtering is utilized to automatically determine coefficient values which reflect normal differences in performance between the monitored engine and others of the same type. Since similar digital filtering is utilized in the determination of the temporal characteristics of the monitored engine parameters, common digital processor structure and processing is utilized to effect both system calibration and the estimate of the parameter trends or temporal characteristics.