Failsafe electronic engine control system overheat shutdown

A jet engine fuel supply system, comprising:

• a fuel supply line having an inlet and an outlet, the inlet adapted to receive fuel from a fuel source, the outlet adapted to supply the fuel to a gas turbine engine combustor;
• a fuel metering valve disposed in flow series in the fuel supply line, the fuel metering valve having a variable area flow orifice through which fuel from the fuel source flows;
• a valve control device coupled to the fuel metering valve, the valve control device further coupled to receive valve commands and operable, in response thereto, to adjust the area of the fuel metering valve variable area flow orifice;
• and
• a controller operable to supply the valve command signals, the controller including:
• a processor rated to operate up to a first temperature value, the processor configured to (i) supply the valve command signals and (ii) perform a periodic computation and, upon successful completion of the periodic computation, to supply an output signal;
• and
• an analog enable circuit rated to operate up to a second temperature value that is greater than the first temperature value, the enable circuit coupled to receive the output signal from the processor and operable, upon receipt thereof, to (i) enable operability of the valve actuator if the periodic computation is successfully completed and (ii) disable operability of the valve actuator if the periodic computation is unsuccessfully completed.