Simulated parameter control for gas turbine engine

For a fuel control that meters fuel to a gas turbine engine having multiple compressor stages, means for providing a synthesized burner pressure signal to be substituted for a measured parameter indicative of the actual burner pressure in the event of failure of the signal indicative of said measured parameter whenever said signal falls outside the range of its normal operating limits comprising, a function generator responding to a signal indicative of the pressure intermediate said compressor stages which has a relationship to the thermodynamic cycle of said gas turbine engine for generating a first signal indicative of a ratio of two parameters where one of said two parameters is a function of burner pressure to be synthesized, means measuring still a different engine operating parameter which is mutually dependent on the measured parameter processed by said function generator for providing a second signal and means for combining said first signal and said second signal for producing an output signal whose value is approximate the signal indicative of actual burner pressure.