FADEC

A full authority digital engine (or electronics) control (FADEC) is a system consisting of a digital computer, called an "electronic engine controller" (EEC) or "engine control unit" (ECU), and its related accessories that control all aspects of aircraft engine performance. FADECs have been produced for both piston engines and jet engines.

The goal of any engine control system is to allow the engine to perform at maximum efficiency for a given condition. Originally, engine control systems consisted of simple mechanical linkages connected physically to the engine. By moving these levers the pilot or the flight engineer could control fuel flow, power output, and many other engine parameters.

Following mechanical means of engine control — with the Kommandogerat mechanical/hydraulic engine control unit for the Third Reich's BMW 801 piston aviation radial engine of World War II as just one notable example of such a precursor — came the introduction of analog electronic engine control. Analog electronic control varies an electrical signal to communicate the desired engine settings. The system was an evident improvement over mechanical control but had its drawbacks, including common electronic noise interference and reliability issues. Full authority analogue control was used in the 1960s and introduced as a component of the Rolls-Royce/Snecma Olympus 593 engine of the supersonic transport aircraft Concorde. However, the more critical inlet control was digital on the production aircraft.

In 1968 Rolls-Royce and Elliott Automation in conjunction with the National Gas Turbine Establishment worked on a digital engine control system that completed several hundred hours of operation on a Rolls-Royce Olympus Mk 320.

Following analog electronic control, the next step was to digital electronic control systems. Later in the 1970s, NASA and Pratt and Whitney experimented with the first experimental FADEC, first flown on an F-111 fitted with a highly modified Pratt & Whitney TF30 left engine. The experiments led to Pratt & Whitney F100 and Pratt & Whitney PW2000 being the first military and civil engines, respectively, fitted with FADEC, and later the Pratt & Whitney PW4000 as the first commercial "dual FADEC" engine. The first FADEC in service was developed for the Harrier II Pegasus engine by Dowty and Smiths Industries Controls.

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