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FADEC

Digital overwatch for the latest engines

December 8, 2022 By Thomas A. Horne
From day one of our flying lives, pilots come to intimately know an airplane’s power controls.
A greatly simplified schematic of a generic FADEC system shows that the FADEC unit is king. It measures inputs to, and outputs from, the engine. Its job is to deliver precise, optimal engine performance—without exceeding any limitations (above). Although most often associated with turbine engines, FADECs are making their way into high-performance piston singles. The panel of a Tecnam P2010 Gran Lusso (right) shows its guarded engine master switch (in red) and the FADEC selector toggle switch (to its right). Auto is the normal switch position; the “force B” switch position lets the pilot select a second, backup FADEC channel. Illustration by Steve Karp.
Zoomed image
A greatly simplified schematic of a generic FADEC system shows that the FADEC unit is king. It measures inputs to, and outputs from, the engine. Its job is to deliver precise, optimal engine performance—without exceeding any limitations (above). Although most often associated with turbine engines, FADECs are making their way into high-performance piston singles. The panel of a Tecnam P2010 Gran Lusso (right) shows its guarded engine master switch (in red) and the FADEC selector toggle switch (to its right). Auto is the normal switch position; the “force B” switch position lets the pilot select a second, backup FADEC channel. Illustration by Steve Karp.

These controls—throttle, propeller (in complex airplanes), and mixture—get a workout every time you fly. When you move them to set power, you’re moving mechanical linkages that directly connect to levers, gears, or other types of actuators on the carburetor or, in airplanes with constant-speed propellers, mechanisms that allow engine oil in and out of the propeller hub. You’re in control.

That’s all well and good, but what if you slam the throttle forward too fast on takeoff? Or set the mixture so lean that cylinder temperatures run too hot? Or set the mixture too rich for your current power and altitude? Here’s where full authority digital engine control (FADEC) comes into play.

FADEC is a relatively recent type of digital engine control that runs from inputs generated by a programmed electronic engine controller. FADEC sensors sample a wide range of variables such as air temperature, altitude, throttle position, engine temperatures and pressures, engine and propeller rpms, fuel flow, electrical system voltage, and a lot more. All this information is sent to the FADEC’s computers and electronic monitors, which have been programmed to keep the engine from exceeding any temperature, speed, or other limits—and also to provide optimum engine performance. Even better, digital engine controls can also mean pushbutton starting and single-lever power controls.

For safety’s sake FADECs come with dual channels. If one circuit malfunctions, the second channel is there for redundancy. Running the pre-takeoff checklist, you’ll check both channels to make sure both are working, just as you check both magnetos in a conventional-ignition engine.

Expect to see more FADEC systems installed in the future. They’re not just for turbine airplanes anymore. You may well encounter them in complex piston singles as you step up to newer, more capable airplanes. Bottom line: For all its complexity, FADECs mean more efficient engine operations, precise engine monitoring, longer service lives, better fuel efficiency, and lower pilot workload.

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Thomas A. Horne
Thomas A. Horne
AOPA Pilot Editor at Large
AOPA Pilot Editor at Large Tom Horne has worked at AOPA since the early 1980s. He began flying in 1975 and has an airline transport pilot and flight instructor certificates. He’s flown everything from ultralights to Gulfstreams and ferried numerous piston airplanes across the Atlantic.
Go to Thomas A. Horne's Profile

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