Failure detection logic for gas turbine engines

The fault detection logic, for a jet engine control system, registers loss of thrust control capability where the thrust is too high or too low on a positive or negative thrust. As an initial fault control parameter (+-EPRerror), a value is registered related to the jet acceleration or deceleration, and a second control parameter (+-N2dot) is measured. Both parameters are each compared with a given threshold value to establish if the thresholds are breached at the same time. It also detects if there is a jet pump, to eliminate signal noise or pump interference. If the thresholds are breached at the same time, an overthrust or underthrust (UTDET) is detected in relation to the positive or negative acceleration. A positive or negative difference (EPRerror) is derived from the threshold value (EPRcmd) and the actual value (EPRactual) for the first parameter, and the second parameter is the positive or negative acceleration (N2dot).