Full Authority Digital Engine Control


The control system is not generally considered to be a limiting factor in the performance of an engine.

FADEC's main purpose is to provide optimum engine efficiency for a given flight condition.

FADEC control the aircraft's engine and propeller in order to perform at a maximum efficiency.

Basic Information

  • FADEC is a system consisting of a digital computer and ancillary components that control an aircraft's engine.
  • FADEC is a self-monitoring, self operating, redundant fail-safe setup.

  • FADEC system eliminate the need for magnetoes, carburetor heat, mixture controls, and engine priming.
  • Engine is controlled based on pressure and temperature. (parameters)
  • Continuously monitors and controls ignition, timing, and fuel mixture/delivery/injection, and spark ignition as an integrated control system.

Basic Information

  • It operates with certain limits provides by the manufacturer of each engine aircraft.
  • The FADEC also allows the manufacturer to program engine limitations and receive engine health and maintenance reports.
  • In the event of loss of primary aircraft-supplied power, the engine controls continue to operate using a Secondary Power Source (SPS). As a control device, the system performs self-diagnostics to determine overall system status and conveys this information to the pilot by various indicators on the Health Status Annunciator (HSA) panel. 
  • FADEC's have been produced for both piston engines and jet engines.




An engine control unit (ECU) is a type of electronic control unit that controls a series of actuators on an internal combustion engine to ensure the optimum running. It does this by reading values from a multitude of sensors within the engine bay, interpreting the data using multidimensional performance maps (called Look-up tables), and adjusting the engine actuators accordingly.

“Brain” of the Engine Control System

ECU divided into an upper and lower portions

  • Lower portion contains the Electronic Circuit Board that processes all data

  • Upper portion contains the ignition coils for the spark plugs

The Electronic circuit board contains two, independent microprocessor controllers called "control channels".

Each control channel is assigned to a single engine cylinder. Since there are two control channels in each MPC (No shared electronic components between the two control channels).

For redundancy, each control channel is capable of operating its assigned cylinder and a cylinder assigned to the second control channel within the same MPC unit.

Primary/Secondary power is supplied by the Cabin Harness through the Bulkhead Connectors.

The status of FADEC system is conveys to the pilot by..


Health Status Annunciator

Discrete lamps in the HSA will illuminate upon detection of system 

  • FADEC WARN: Engine Failure may be imminent, more than one cylinder is affected…land ASAP
  • FADEC CAUTION: 99.99% of installed components are working.  

  • PPWR FAIL: Primary Battery is not being charged, will be accompanied by EBAT FAIL…you will start draining both batteries and have at least 60 minutes to land. Your secondary battery will only power FADEC, AI, and Turn Coordinator

  • EBAT FAIL: Backup Battery not being charged

  • FUEL PUMP: illuminates when Fuel Boost Pump Mode Switch is in ON or OFF. If this light is illuminated it means that you are manually controlling the fuel pump or that the fuel pressure is out of the 20-40 psi range.  

  • WOT: below HSA panel. Illuminates when Throttle Position Switch (TPS) is contacted (full throttle), signal sent to ECU that max power is required which causes FADEC to set fuel to air ratio for Best Power 


An engine SENSOR is an electrical device that changes circuit resistance or voltage with a change in a condition such as temperature, pressure or position 


(Speed and position of crank)

Fuel Pressure sensors

Manifold Pressure sensors

Manifold Air Temp. sensors

CHT sensors

EGT sensors

  •  All critical sensors are dually redundant with one sensor from each type of pair connected to control channels in different ECUs.

  • SYNTHETIC SOFTWARE DEFAULT VALUES are also used in the unlikely event that both sensors of a redundant pair fail.


  • The ignition system consists of the high-voltage coils atop of ECU, the high-voltage harness, and spark plug.

  • One end of each lead on the high-voltage harness attach to a spark plug, and the other end of the lead wire attaches to the spark plug towers on each ECU.

  • Two coil packs are located in the upper portion of the ECU. Each coil pack generates a high-voltage pulse for two spark plug towers.


  • One tower fires a positive polarity pulse and the other of the same coil fires a negative polarity pulse

  • Each ECU controls the  ignition spark for two engine cylinders.

  • The high-voltage harness carries energy from the ECU spark towers to the spark plug on the engine.


The ignition system is waste-spark type

Each cylinder's spark plug are fired twice per engine cycle

The FADEC system schedules the spark timing and intensity using MPC units

Spark timing and intensity are variable throughout the engine's operating range and is depend upon the engine load conditions.

output: Fuel Injection System

The FADEC system schedules the amount of fuel and the injection timing for multi-port fuel injectors, thereby eliminating the mixture control.

Compensates for changes in altitude by monitoring the intake manifold pressure.

Power Supplies (Electrical System)

 Requires two independent power sources.

  • The primary source [Primary Power Source (PPS)] is provides from the aircraft power bus.
  • The redundant source [Secondary Power Source (SPS)] can be provided from

                    A dedicated backup battery

                    A dedicated alternator

                    An essential aircraft electrical bus  


Better fuel efficiency

Provide semi-automatic engine starting

Reduces pilot work load

Safer as the multiple channel FADEC computer provides redundency in case of failure

Save weight


Have no form of manual override

If a total FADEC failure occurs, the engine fails

High system complexity

High Cost

When everything seems to be going against you, remember that the airplane takes off against the wind,    not with it.

 Henry Ford

Aircraft Ignition Systems


Submitted by: AM54 AA&AD

KRITTABOON J.                               PROMCHOK I.

WARUNYOO M.                                PITIPAT M.       

JARUWIT  W.                                    PATT K.

NATTAPON S.                                  KANOKCHAI S.

PASUTA B.                                        PATOMPONG S.                  

NATTAKAN P.                                   WANACHAT M.



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Public - 7/12/16, 7:04 AM