FADEC_Full-Authority Digital Engine Control

• What is FADEC?What is FADEC?• How Does a FADEC Work?How Does a FADEC Work?• A BackgrounderA Backgrounder• Modern Engine Control SystemModern Engine Control System• FADEC FunctionsFADEC Functions• FADEC Infrastructure (Simplified)FADEC Infrastructure (Simplified)• Essential FeaturesEssential Features• Schematic DiagramSchematic Diagram• Advantages & LimitationsAdvantages & Limitations

FADECFADEC

WHAT IS FADEC?WHAT IS FADEC?

FADEC:FADEC: Full Authority Digital Engine Full Authority Digital Engine Control System is aControl System is a digital electronic digital electronic control system for gas turbine engines control system for gas turbine engines that is able to autonomously control that is able to autonomously control the engine throughout its whole the engine throughout its whole operating range from demanded engine operating range from demanded engine start until demanded engine shut start until demanded engine shut down, in both normal and fault down, in both normal and fault conditions. conditions.

The FADEC is a self-monitoring, self-The FADEC is a self-monitoring, self-operating, redundant fail-safe setup.operating, redundant fail-safe setup.

FADEC comprises of a digital computer FADEC comprises of a digital computer (Electronic Engine Control # EEC ) and (Electronic Engine Control # EEC ) and the other accessories that control all the other accessories that control all the aspects of aircraft engine the aspects of aircraft engine performance .performance .


FADEC is the key system of gas turbine FADEC is the key system of gas turbine engines. Its basic purpose is to provide engines. Its basic purpose is to provide optimum engine efficiency for a given optimum engine efficiency for a given flight condition. FADEC also controls flight condition. FADEC also controls engine starting and restarting.engine starting and restarting.

One of the system roles is to lower the One of the system roles is to lower the cognitive load of pilots while they cognitive load of pilots while they operate turbojet engines , and to operate turbojet engines , and to reduce the occurrence of pilot errors .reduce the occurrence of pilot errors .

FADEC not only provides for efficient FADEC not only provides for efficient engine operation, it also allows the engine operation, it also allows the manufacturer to program engine manufacturer to program engine limitations and receive engine health limitations and receive engine health and maintenance reports.and maintenance reports.


To be a true, 100%, Full Authority To be a true, 100%, Full Authority Digital Engine Control, there must not Digital Engine Control, there must not be any form of manual override be any form of manual override available. This literally places full available. This literally places full authority to the operating parameters authority to the operating parameters of the engine in the hands of the of the engine in the hands of the computer. If a total FADEC failure computer. If a total FADEC failure occurs, the engine fails. occurs, the engine fails.

If the engine is controlled digitally and If the engine is controlled digitally and electronically but allows for manual electronically but allows for manual override, it is considered solely an override, it is considered solely an Electronic Engine Control Electronic Engine Control (EEC)(EEC) or or Electronic Control Unit Electronic Control Unit (ECU). (ECU).

An EEC, though a component of a An EEC, though a component of a FADEC, is not by itself FADEC. When FADEC, is not by itself FADEC. When standing alone, the EEC makes all of standing alone, the EEC makes all of the decisions until the pilot wishes to the decisions until the pilot wishes to intervene.intervene.


Modern ECUs use a microprocessor Modern ECUs use a microprocessor which can process the inputs from the which can process the inputs from the engine sensors in real time. An engine sensors in real time. An electronic control unit contains the electronic control unit contains the hardware and software (firmware). hardware and software (firmware). The hardware consists of electronic The hardware consists of electronic components on a printed circuit board components on a printed circuit board (PCB), ceramic substrate or a thin (PCB), ceramic substrate or a thin laminate substrate. The main laminate substrate. The main component on this circuit board is a component on this circuit board is a microcontroller chip (CPU). microcontroller chip (CPU). The software is stored in the The software is stored in the microcontroller or other chips on the microcontroller or other chips on the PCB, typically in EPROMs or flash PCB, typically in EPROMs or flash memory so the CPU can be re-memory so the CPU can be re-programmed by uploading updated programmed by uploading updated code or replacing chips. This is also code or replacing chips. This is also referred to as an Electronic Engine referred to as an Electronic Engine Management System (EMS).Management System (EMS).


The benefits of digital electronic The benefits of digital electronic control of mechanical systems are control of mechanical systems are evident in greater precision and an evident in greater precision and an ability to measure or predict ability to measure or predict performance degradation and incipient performance degradation and incipient failure. failure. Typical examples of this are digital Typical examples of this are digital implementations of flight control or fly-implementations of flight control or fly-by-wire by-wire (FBW)(FBW) and digital engine and digital engine control, or Full-Authority Digital Engine control, or Full-Authority Digital Engine Control Control (FADEC).(FADEC).Integrated Flight and Propulsion Integrated Flight and Propulsion Control (IFPC) allows closer integration Control (IFPC) allows closer integration of the aircraft flight control and engine of the aircraft flight control and engine control systems. Flight control systems control systems. Flight control systems are virtually all fly-by-wire in the are virtually all fly-by-wire in the modern fighter aircraft of today; the modern fighter aircraft of today; the benefits being weight reduction and benefits being weight reduction and improved handling characteristics. improved handling characteristics.


New engines are likewise adopting New engines are likewise adopting FADEC for the benefits offered by FADEC for the benefits offered by digital control.digital control.

As substantial benefits of improved As substantial benefits of improved reliability and performance are reliability and performance are realized, e.g. weight reduction and realized, e.g. weight reduction and other improvements in system other improvements in system integration and data flow, the level of integration and data flow, the level of systems integration becomes systems integration becomes correspondingly more ambitious.correspondingly more ambitious.


Present primary engine control is by Present primary engine control is by means of a FADEC which is normally means of a FADEC which is normally located on the engine fan casing. located on the engine fan casing.

However, there are many features of However, there are many features of engine control which are distributed engine control which are distributed around the engine – such as reverse around the engine – such as reverse thrust, presently pneumatically actuated thrust, presently pneumatically actuated – which would need to be actuated by – which would need to be actuated by alternative means in a more-electric alternative means in a more-electric engine. engine.

This leads to the possibility of using This leads to the possibility of using distributed engine control.distributed engine control.

HOW DOES A FADEC WORK?HOW DOES A FADEC WORK?

FADEC works by receiving multiple FADEC works by receiving multiple input variables of the current flight input variables of the current flight condition including air density, throttle condition including air density, throttle lever position, engine temperatures, lever position, engine temperatures, engine pressures, and many others. engine pressures, and many others.

Each FADEC is essentially a centralized Each FADEC is essentially a centralized system, with a redundant, central system, with a redundant, central computer and centrally located analog computer and centrally located analog signal interfacing circuitry for signal interfacing circuitry for interfacing with sensors and actuators interfacing with sensors and actuators located throughout the propulsion located throughout the propulsion system. system.

Engine operating parameters such as fuelEngine operating parameters such as fuelflow, stator vane position, bleed valve flow, stator vane position, bleed valve

positionpositionand others are computed from this data and others are computed from this data

andandapplied as appropriate.applied as appropriate.

For example, to avoid exceeding a certainFor example, to avoid exceeding a certainengine temperature, the FADEC can beengine temperature, the FADEC can beprogrammed to automatically take theprogrammed to automatically take thenecessary measures without pilot necessary measures without pilot

intervention.intervention.

The inputs are received by the EEC andThe inputs are received by the EEC andanalyzed up to 70 times per second.analyzed up to 70 times per second.



FADEC computes the appropriate thrust FADEC computes the appropriate thrust settings and applies them. settings and applies them.

During flight, small changes in During flight, small changes in operation are constantly being made to operation are constantly being made to maintain efficiency. maintain efficiency.

Maximum thrust is available for Maximum thrust is available for emergency situations if the throttle is emergency situations if the throttle is advanced to full, but remember, advanced to full, but remember, limitations can’t be exceeded.limitations can’t be exceeded.

Another new feature of the FADEC Another new feature of the FADEC system is the ability to record the last system is the ability to record the last 900 hours of flight. 900 hours of flight.

With readings taken every second, this With readings taken every second, this stored information can be used to stored information can be used to diagnose problem areas as well as diagnose problem areas as well as review recent flight history.review recent flight history.

A BACKGROUNDERA BACKGROUNDER

The FADEC systems were first used in theThe FADEC systems were first used in theautomotive Industry where it is well proven.automotive Industry where it is well proven.Now-a-days airlines and the militaries all Now-a-days airlines and the militaries all

overoverthe world incorporate it on turbine poweredthe world incorporate it on turbine poweredaircraft.aircraft.FADECs are made for piston engine and jetFADECs are made for piston engine and jetengines both but they differ in the way ofengines both but they differ in the way ofcontrolling the engine .controlling the engine .Advanced, intelligent & robust propulsionAdvanced, intelligent & robust propulsioncontrols are critical for improving the safetycontrols are critical for improving the safetyand maintainability of future propulsionand maintainability of future propulsionsystems. systems. Propulsion system reliability is considered toPropulsion system reliability is considered tobe critical for aircraft survival. Hence, FADECbe critical for aircraft survival. Hence, FADECsystems came into being.systems came into being.


FADEC is now common on many engines andFADEC is now common on many engines andsemiconductor and equipment coolingsemiconductor and equipment coolingtechnology has advanced so that control technology has advanced so that control

unitsunitscan now be mounted on the engine and stillcan now be mounted on the engine and stillprovide highly reliable operation for longprovide highly reliable operation for longperiods. periods.

Developing and implementing modernDeveloping and implementing modernintelligent engine systems requires theintelligent engine systems requires theintroduction of numerous sensors, actuatorsintroduction of numerous sensors, actuatorsand processors to provide the advancedand processors to provide the advancedfunctionality. functionality.


The application of artificial intelligence The application of artificial intelligence andand

knowledge-based system for both knowledge-based system for both softwaresoftware

and hardware provides the foundation and hardware provides the foundation forfor

building the intelligent control system of building the intelligent control system of thethe

future.future.

With time, control systems became moreWith time, control systems became moresophisticated with the introduction ofsophisticated with the introduction ofadditional engine condition sensors andadditional engine condition sensors andmultiple servo-loops. multiple servo-loops.


The task of handling engines was eased by theThe task of handling engines was eased by theintroduction of electronic control in the form ofintroduction of electronic control in the form ofmagnetic amplifiers in early civil and militarymagnetic amplifiers in early civil and militaryaircraft.aircraft.

The mag-amp allowed engines to be stabilizedThe mag-amp allowed engines to be stabilizedat any speed in the throttle range by at any speed in the throttle range by introducing a servo-loop with engine exhaustintroducing a servo-loop with engine exhaustgas temperature as a measure of enginegas temperature as a measure of enginespeed and an analogue fuel valve to controlspeed and an analogue fuel valve to controlfuel flow. fuel flow.


Transistors, integrated circuits and highTransistors, integrated circuits and high

temperature semi-conductors have all temperature semi-conductors have all playedplayed

a part in the evolution of control systems a part in the evolution of control systems fromfrom

range temperature control through to fullrange temperature control through to full

digital engine control systems.digital engine control systems.

This allowed the pilot to accelerate andThis allowed the pilot to accelerate anddecelerate the engine while the controldecelerate the engine while the controlsystem limited fuel flows to prevent over-system limited fuel flows to prevent over-speeds or excessive temperatures.speeds or excessive temperatures.


With modern FADEC systems there are noWith modern FADEC systems there are nomechanical control rods or mechanicalmechanical control rods or mechanicalreversions, and the pilot can perform reversions, and the pilot can perform

carefreecarefreehandling of the engine throughout the handling of the engine throughout the

flightflightenvelope.envelope.

On modern aircraft the engine is supervisedOn modern aircraft the engine is supervisedby a computer to allow the pilot to operate by a computer to allow the pilot to operate

atatmaximum performance in a combat aircraft maximum performance in a combat aircraft

ororat optimum fuel economy in a passengerat optimum fuel economy in a passengercarrying aircraft.carrying aircraft.


Today, each FADEC is unique andToday, each FADEC is unique andtherefore is expensive to develop,therefore is expensive to develop,produce, maintain, and upgrade for itsproduce, maintain, and upgrade for itsparticular application. particular application.

In the future, it is desired to establish In the future, it is desired to establish aa

universal or common standard foruniversal or common standard forengine controls and accessories. Thisengine controls and accessories. Thiswill significantly reduce the highwill significantly reduce the highdevelopment and support costs acrossdevelopment and support costs acrossplatforms.platforms.

DESIGN REQUIREMENTS OF DESIGN REQUIREMENTS OF MODERN ENGINE CONTROL MODERN ENGINE CONTROL

SYSTEMSYSTEM • Speed / Accuracy / Speed / Accuracy /

Ease of Control (Least Ease of Control (Least Aircrew Workloads)Aircrew Workloads)

• Wide Operational Wide Operational Range Range

• Reliability & Reliability & Operational SafetyOperational Safety

• Low Operating & Low Operating & Maintenance CostsMaintenance Costs

• Should Not Add WeightShould Not Add Weight• Fuel EfficiencyFuel Efficiency• Dependable StartsDependable Starts

FADEC : FUNCTIONSFADEC : FUNCTIONS

ENGINE CONTROLENGINE CONTROL

ACQUIREACQUIRESENSOR DATASENSOR DATA

PROCESSPROCESSCONTROL LAWSCONTROL LAWS

COMMANDCOMMANDACTUATORSACTUATORS

AIRFRAMEAIRFRAMECOMMUNICATIONCOMMUNICATION

REPORT REPORT ENGINE STATUSENGINE STATUS

RECEIVE ENGINERECEIVE ENGINEPOWER COMMANDPOWER COMMAND

ENGINEENGINE HEALTHHEALTHMONITORINGMONITORING

DIAGNOSTICDIAGNOSTIC

PROGNOSTICPROGNOSTIC

ADAPTIVEADAPTIVE

FADECFADEC

FADEC : INFRASTRUCTUREFADEC : INFRASTRUCTURE

CONTROL OPERATIONS IN GAS TURBINE CONTROL OPERATIONS IN GAS TURBINE ENGINESENGINES


CONTROL OPERATIONS IN GAS TURBINE CONTROL OPERATIONS IN GAS TURBINE ENGINESENGINES

- Air Control - Air Control (Compressor Entry)- Fuel Control - Fuel Control (Main / AB / Starting System)- Ignition Control- Ignition Control

- Starting Control- Starting Control

- Lubrication Control- Lubrication Control

- Surge Control - Surge Control (Through Bleed Valve)- Thrust Control - Thrust Control (Through Exhaust Nozzle)

FADEC : INFRASTRUCTUREFADEC : INFRASTRUCTURE SAMPLE CHAIN OF CONTROL (MECH.) SAMPLE CHAIN OF CONTROL (MECH.)

OPERATIONOPERATION

FADEC COMPUTERFADEC COMPUTER

GEAR DRIVENGEAR DRIVENMECHANICAL PUMPMECHANICAL PUMP

ELECTRO-HYDRO-MECHNICAL ELECTRO-HYDRO-MECHNICAL CONTROL UNITCONTROL UNIT

ACTUATEDACTUATEDASSEMBLYASSEMBLY

SOLENOIDSOLENOIDVALVESVALVES

SERVOSERVOACTUATINGACTUATING

MOTORSMOTORS

WORKING FLUID WORKING FLUID FROMFROM

ENGINE / AIRCRAFTENGINE / AIRCRAFT

AIRCRAFTAIRCRAFTCOMPUTERCOMPUTER

COCKPITCOCKPIT

POSITIONPOSITIONSENSORSSENSORS

MECHANICALMECHANICALACTUATORSACTUATORS

POSITIONPOSITIONSENSOR-1SENSOR-1

POSITIONPOSITIONSENSOR-2SENSOR-2

FADEC : INFRASTRUCTUREFADEC : INFRASTRUCTURE SAMPLE CHAIN OF CONTROL (ELECT.) SAMPLE CHAIN OF CONTROL (ELECT.)

OPERATIONOPERATION

ELECTRO-HYDRO-MECHNICAL ELECTRO-HYDRO-MECHNICAL CONTROL UNITCONTROL UNIT POSITIONPOSITION

SENSOR-1SENSOR-1SOLENOIDSOLENOIDVALVESVALVES

SERVOSERVOACTUATINGACTUATING

MOTORSMOTORS

POSITIONPOSITIONSENSOR-2SENSOR-2POSITIONPOSITION

SENSORSSENSORS

MECHANICALMECHANICALACTUATORSACTUATORS

FADECFADECCOMPUTERCOMPUTER

POWERPOWERSUPPLYSUPPLY

VARIOUS INPUTSVARIOUS INPUTSFROMFROM

ENGINE & AIRCRAFTENGINE & AIRCRAFT DISPLAY PANELDISPLAY PANELIN COCKPITIN COCKPIT

PILOT’s THROTTLEPILOT’s THROTTLEIN COCKPITIN COCKPIT


HARDWARE:HARDWARE:

- Dual Power Supply- Dual Power Supply- FADEC Computer FADEC Computer (With Logic Circuit PCBs &

Programmed / Programmable Memory)- A Set of Servo Actuating Motors / Solenoid A Set of Servo Actuating Motors / Solenoid

Valves / Position Sensors Valves / Position Sensors (for every System Control Unit)

- Dual Position Sensors for Actuators Dual Position Sensors for Actuators (of every System)

- A Set of Electrical Harnesses A Set of Electrical Harnesses (for every System)

- Display Panel with Indicators / Warning Display Panel with Indicators / Warning Lights Lights (in Cockpit)

- Multiple Engine RPM, Pressure Sensors & Multiple Engine RPM, Pressure Sensors & ThermocouplesThermocouples

- Pilot’s ThrottlePilot’s Throttle

FADEC : INFRASTRUCTUREFADEC : INFRASTRUCTURESOFTWARE:SOFTWARE:

- EPR Schedules - EPR Schedules (For Thrust, over Entire Range of Engine Operation Without FADEC Computer Failure)

- N Schedules N Schedules (For Thrust as per Pilot’s Throttle, Engine Operation in case of Limited FADEC Computer Functionality)

Note:Note: In case of certain degree of FADEC In case of certain degree of FADEC failure there failure there is an automatic mode is an automatic mode switch-over from EPR to N switch-over from EPR to N rating. rating. However, if the failure disappears, the However, if the failure disappears, the pilot can reset the mode to switch-back to pilot can reset the mode to switch-back to EPR EPR mode.mode.

FADEC : INFRASTRUCTUREFADEC : INFRASTRUCTURE INPUTS:INPUTS:

From Aircraft.From Aircraft.

- Ambient TemperatureAmbient Temperature- AltitudeAltitude- Mach NumberMach Number- Angle of AttackAngle of Attack- Impact PressureImpact Pressure- Landing Gear Position Landing Gear Position - Missile / Rocket Firing Signals etc.Missile / Rocket Firing Signals etc.

FADEC : INFRASTRUCTUREFADEC : INFRASTRUCTURE INPUTS:INPUTS:

From Engine.From Engine.

- Throttle Lever Position Throttle Lever Position - RPMRPM- Turbine Outlet / Exhaust Gas Turbine Outlet / Exhaust Gas

TemperatureTemperature- Exhaust Nozzle AreaExhaust Nozzle Area- Fan Duct Flaps PositionFan Duct Flaps Position- Bearing TemperaturesBearing Temperatures- Engine VibrationEngine Vibration- Engine PressuresEngine Pressures

FADEC : INFRASTRUCTUREFADEC : INFRASTRUCTURE SIMPLIFIED FADEC ARCHITECTURESIMPLIFIED FADEC ARCHITECTURE

FADECFADECLANE-ALANE-A

MONITORMONITORFADECFADECLANE-ALANE-A

CONTROLCONTROL

FADECFADECLANE-BLANE-B

MONITORMONITORFADECFADECLANE-BLANE-B

CONTROLCONTROL

FADEC LANE-AFADEC LANE-A

FADEC LANE-BFADEC LANE-BENGINEENGINETHRUSTTHRUSTDEMANDDEMAND

ENGINEENGINEFUELFUEL

DEMANDDEMAND


SAMPLIFIED FADEC ARCHITECHTURESAMPLIFIED FADEC ARCHITECHTURE

This simplified architecture is typical of manyThis simplified architecture is typical of manydual-channel FADECs. dual-channel FADECs.

There are two independent lanes: Lane A andThere are two independent lanes: Lane A andLane B. Each lane comprises a Command andLane B. Each lane comprises a Command andMonitor portion, which are interconnected forMonitor portion, which are interconnected forcross monitoring purposes, and undertakescross monitoring purposes, and undertakesthe task of metering the fuel flow to the enginethe task of metering the fuel flow to the enginein accordance with the necessary control lawsin accordance with the necessary control lawsto satisfy the flight crew thrust command. to satisfy the flight crew thrust command.

The analysis required to decide upon theThe analysis required to decide upon theimpact of certain failures in conjunction withimpact of certain failures in conjunction withothers, requires a Markov model in order to beothers, requires a Markov model in order to beable to understand the dependencies. able to understand the dependencies.


MARKOV ANALYSIS MODELMARKOV ANALYSIS MODEL

•By using this model the effects of By using this model the effects of interrelated failures can be examined. interrelated failures can be examined. •The model has a total of 16 states as shown The model has a total of 16 states as shown by the number in the bottom right-hand by the number in the bottom right-hand corner of the appropriate box. corner of the appropriate box. •Each box relates to the serviceability state Each box relates to the serviceability state of the Lane A Command (Ca) and Monitor of the Lane A Command (Ca) and Monitor (Ma) channels and Lane B Command (Cb) and (Ma) channels and Lane B Command (Cb) and Monitor (Mb) channels. Monitor (Mb) channels. •These range from the fully serviceable state These range from the fully serviceable state in box 1 through a series of failure conditions in box 1 through a series of failure conditions to the totally failed state in box 16. to the totally failed state in box 16. •Clearly most normal operating conditions Clearly most normal operating conditions are going to be in the left-hand region of the are going to be in the left-hand region of the model.model.

FADEC : INFRASTRUCTUREFADEC : INFRASTRUCTUREMARKOV MODEL ANALYSISMARKOV MODEL ANALYSIS

CaMa.CbMb 1CaMa.CbMb 1

CaMa.CaMa.CbCbMb 4Mb 4

CaCaMa.CbMb 2Ma.CbMb 2

CaCaMaMa.CbMb 3.CbMb 3

CaMa.CbCaMa.CbMbMb 5 5

CaCaMa.Ma.CbMbCbMb 14 14

CaMaCaMa..CbCbMb 12Mb 12

CaMaCaMa.Cb.CbMbMb 13 13

CaCaMaMa..CbMbCbMb 15 15

CaMaCaMa..CbMbCbMb 16 16

CaCaMa.CbMa.CbMbMb 8 8

CaMaCaMa.CbMb 6.CbMb 6

CaCaMa.Ma.CbCbMb 7Mb 7

CaCaMaMa..CbCbMb 9Mb 9

CaCaMaMa.Cb.CbMbMb 10 10

CaMa.CaMa.CbMbCbMb 11 11

CONTROLLABLECONTROLLABLEENGINEENGINE

DISPACHABLEDISPACHABLEENGINEENGINE

ENGINEENGINESHUT-DOWNSHUT-DOWN

NO FAILURE 1 FAILURE 2 FAILURE 3 FAILURE NO FAILURE 1 FAILURE 2 FAILURE 3 FAILURE 4 FAILURE 4 FAILURE


SIMPLIFIED FADEC ARCHITECHTURESIMPLIFIED FADEC ARCHITECHTUREConcentrating on the left-hand side of the model it Concentrating on the left-hand side of the model it

cancanbe seen that the fully serviceable state in box 1 be seen that the fully serviceable state in box 1

cancanmigrate to any one of six states:migrate to any one of six states:

– Failure of Command channel A results in state Failure of Command channel A results in state 2 being reached.2 being reached.

– Failure of Monitor channel A results in state 3 Failure of Monitor channel A results in state 3 being reached.being reached.

– Failure of Command channel B results in state Failure of Command channel B results in state 4 being reached.4 being reached.

– Failure of Monitor channel B results in state 5 Failure of Monitor channel B results in state 5 being reached.being reached.

– Failure of the cross-monitor between Failure of the cross-monitor between Command A and Monitor A results in both Command A and Monitor A results in both being lost simultaneously and reaching state being lost simultaneously and reaching state 6.6.

– Failure of the cross-monitor between Failure of the cross-monitor between Command B and Monitor B results in both Command B and Monitor B results in both being lost simultaneously and reaching state being lost simultaneously and reaching state 11.11.


SIMPLIFIED FADEC ARCHITECHTURESIMPLIFIED FADEC ARCHITECHTUREAll of these failure states result in an engine whichAll of these failure states result in an engine whichmay still be controlled by the FADEC. However,may still be controlled by the FADEC. However,further failures beyond this point may result in anfurther failures beyond this point may result in anengine which may not be controllable either becauseengine which may not be controllable either becauseboth control channels are inoperative or because theboth control channels are inoperative or because the‘‘good’ control and monitor lanes are in opposinggood’ control and monitor lanes are in opposingchannels or worse. channels or worse.

The model shown above is constructed according toThe model shown above is constructed according tothe following rules: an engine may be dispatched as athe following rules: an engine may be dispatched as a‘‘get-you-home’ measure provided that only oneget-you-home’ measure provided that only onemonitor channel has failed. monitor channel has failed.

This means that states 3 and 5 are dispatchable: butThis means that states 3 and 5 are dispatchable: butnot states 2, 4, 6, or 11 as subsequent failures couldnot states 2, 4, 6, or 11 as subsequent failures couldresult in engine shut-down.result in engine shut-down.

FADEC : ESSENTIAL FADEC : ESSENTIAL FEATURESFEATURES

MILITARY / TRANSPORT AIRCRAFTMILITARY / TRANSPORT AIRCRAFT-- LP Compressor EGV ControlLP Compressor EGV Control- HP Compressor EGV ControlHP Compressor EGV Control- Fan Duct Flaps ControlFan Duct Flaps Control-- Main Fuel ControlMain Fuel Control- Core AB Fuel ControlCore AB Fuel Control- Fan AB Fuel Control Fan AB Fuel Control - Starting Fuel Control Starting Fuel Control - Ignition ControlIgnition Control- Bleed Valve ControlBleed Valve Control- Exhaust Nozzle ControlExhaust Nozzle Control- Lubrication ControlLubrication Control

FADEC : SCHEMATIC FADEC : SCHEMATIC DIAGRAMDIAGRAM

AIRCRAFTAIRCRAFTCOMPUTERCOMPUTER

PILOTPILOTININ

COCKPITCOCKPIT

MAIN FUELMAIN FUELCONTROLCONTROL

CORE AB FUELCORE AB FUELCONTROLCONTROL

STARTINGSTARTING&&

IGNITIONIGNITIONCONTROLCONTROL

FAN AB FUELFAN AB FUELCONTROLCONTROL

EXHAUST NOZZLEEXHAUST NOZZLECONTROLCONTROL

FAN DUCT FLAPSFAN DUCT FLAPSCONTROLCONTROL

BLEED VALVEBLEED VALVECONTROLCONTROL

LP COMPRESSORLP COMPRESSORAIR EGV CONTROLAIR EGV CONTROL

HP COMPRESSORHP COMPRESSORAIR EGV CONTROLAIR EGV CONTROL

FADECFADECEECUEECU

POWERPOWERSUPPLYSUPPLY

CPU /Memory

Actuationelectronics

Sensorelectronics

Sensorelectronics


Sensorelectronics


Actuator_1

Sensor_1

Sensor_ j

Actuator_n

Sensor_2

Actuator_2

Communication

Power

BU

S

FADEC

Centralized Engine Control

Communication

CENTRALIZED CONTROL ARCHITECTURECENTRALIZED CONTROL ARCHITECTURE Each function resides within the FADEC and uses unique point-to-Each function resides within the FADEC and uses unique point-to-point analog connections to system effectors.point analog connections to system effectors.

CPU /Memory


Sensorelectronics

Sensorelectronics


Sensorelectronics


Actuator_1

Sensor_1

Sensor_ j

Actuator_n

Sensor_2

Actuator_2

Communication

Power

BU

S

FADEC

Centralized Engine Control

Communication

DISTRIBUTED CONTROL ARCHITECTUREDISTRIBUTED CONTROL ARCHITECTURE Functions are distributed outside of the FADEC and communicate Functions are distributed outside of the FADEC and communicate via a common interface standard.via a common interface standard.

FADEC : ADVANTAGESFADEC : ADVANTAGES

-- Reduced Aircrew Workload.Reduced Aircrew Workload.- Improved Fuel Efficiency up to 15% Improved Fuel Efficiency up to 15%

(Due to faster, Accurate Engine (Due to faster, Accurate Engine Control no trimming is required).Control no trimming is required).

- Reduced Aircraft Weight and Engine Reduced Aircraft Weight and Engine Size (Due to Absence of Heavy Size (Due to Absence of Heavy Mechanical Assemblies, No Scattering Mechanical Assemblies, No Scattering of Pipelines & Electrical Wirings).of Pipelines & Electrical Wirings).

- Improved Reliability (Due to Improved Reliability (Due to Redundancy and Dual Channel).Redundancy and Dual Channel).

- Enhanced Engine Life (Due to Engine Enhanced Engine Life (Due to Engine Operation in Safer / Mean Range). Operation in Safer / Mean Range).

FADEC : ADVANTAGESFADEC : ADVANTAGES

- Minimum Maintenance due to On Minimum Maintenance due to On Board Computer Guided Board Computer Guided Troubleshooting ( Aircraft can return Troubleshooting ( Aircraft can return to Flying at the Earliest).to Flying at the Earliest).

- Isochronous Idle speed leads to Isochronous Idle speed leads to Smoother Engine Starts. Smoother Engine Starts.

-- Maximum Performance in a combat Maximum Performance in a combat aircraft or at Optimum Fuel Economy aircraft or at Optimum Fuel Economy in a Transport Aircraft are possible in a Transport Aircraft are possible after necessary Adaptation / after necessary Adaptation / Programming of FADEC Computer. Programming of FADEC Computer.

FADEC : ADVANTAGESFADEC : ADVANTAGES -- Auto-testing removes the need for Auto-testing removes the need for

test-running the engine after minor test-running the engine after minor maintenance work ( Resulting in maintenance work ( Resulting in annual savings of millions of gallon of annual savings of millions of gallon of fuel for the fleet.fuel for the fleet.

FADEC : LIMITATIONSFADEC : LIMITATIONS

- Pilot can not override the FADEC Pilot can not override the FADEC

Control.Control.

- In the event of complete FADEC In the event of complete FADEC Failure, pilot left with no other option Failure, pilot left with no other option than having to fly with least than having to fly with least performance, just sufficient to land performance, just sufficient to land safely. safely. (This limitation has been removed in modern transport aircraft by having two FADEC Computers.)

FADEC: ANY QUESTIONFADEC: ANY QUESTION

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FADEC_Full-Authority Digital Engine Control

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