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 engine control systems pdf the flight engineer could control fuel flow, power output, and many other engine parameters. 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. However, the more critical inlet control was digital on the production aircraft. Following analog electronic control, the next step was to digital electronic control systems. True full authority digital engine controls have no form of manual override available, placing full authority over the operating parameters of the engine in the hands of the computer. If a total FADEC failure occurs, the engine fails. An EEC, though a component of a FADEC, is not by itself FADEC. When standing alone, the EEC makes all of the decisions until the pilot wishes to intervene.