Abstract: The software for the electronic engine control system for a gas turbine engine responding to a temperature sensor measuring the gas path temperature at the inlet of the engine is modified to include means for preventing the control system from overreacting to excessive signal noise. The lead time constant is multiplied by a rate bias factor that may modified as a function of aircraft and/or engine operation conditions to reduce the lead compensation solely when the noise level goes beyond a predetermined threshold.

Abstract: A system for detecting the failure of a control system and its object includes a mathematical model of the control system and its object which continuously predicts the output of the object. An error signal is continuously calculated which is the difference between the model output and the actual output of the object. Error signals exceeding a predetermined minimum value or deadband are integrated; but the integral is reset to zero whenever the error signal value falls within a predetermined range indicative of normal steady state operating tolerances. If the value of the integral reaches a specified level before being reset to zero, a failure signal is triggered. This failure detection system can be made sensitive to relatively small error signals without triggering a false failure signal if the small error was the result of only a temporary problem or due to inaccuracies in model simulation.

Abstract: An integral plus proportional control system responding to more than one variable controls a single actuator wherein the integral gain is selected in accordance with the error of that variable which is being controlled to compensate for varying process dynamics. An error selector serves to discriminate the error signal which is being controlled and synchronously selects the gain of the integrator.