Electronic Engine Control

© International Aero Engines Inc 2000

Electronic Engine ControlElectronic Engine Control


Full Authority Digital Engine Full Authority Digital Engine Control SystemControl System

(F.A.D.E.C.)(F.A.D.E.C.)


IntroductionIntroduction

The V2500 uses a Full Authority Digital

Engine Control (FADEC)

The FADEC comprises:

• Sensor inputs.

• Data inputs.

• The Electronic Engine Control (E.E.C.)

unit.


Output devices include:

• Solenoids.

• Fuel Servo Operated Actuators.

• Pnuematic Servo Operated Devices.

• Dual Electrical Harness.

Introduction Introduction


Engine Electronic ControlEngine Electronic Control

• The heart of the FADEC is the

Electronic Engine Control Unit (E.E.C.).

• Fan Case mounted unit.

• ‘Shielded’ and ‘grounded’ as protection

against Electro Magnetic Interference -

mainly lightning strikes.


© International Aero Engines Inc 2000© International Aero Engines Inc 2000


EEC Mounting point




Engine Electronic ControlEngine Electronic Control(Features)(Features)

• Vibration Isolation Mountings.

• Lightning Strike Protection.

• Size - 15.9” x 20.1” x 4.4”

• Weight - 41 lbs.

• Two independent electronic channels.

• Two independent power supplies from dedicated generator.

• Built in handle to facilitate removal.


Carrying Handle


EEC DescriptionEEC Description

• 2 identical electronic circuits - identified as ‘Channel A & B’.

• Each channel receives identical signals and data from both the aircraft and engine systems such as:

• Air pressures, air temperatures, exhaust gas temperatures and rotor speeds.


Electronic Engine ControlElectronic Engine Control


EEC Description EEC Description

• The EEC also transmits engine performance data to the aircraft, this data is used in:

Thrust Management. Condition Monitoring Systems. Flight Deck Display.

• Each EEC channel can exercise full control of all engine functions.


EEC Description EEC Description

• Control alternates automatically between Channel ‘A’ and ‘B’ for consecutive flights.

• The channel not in control being nominated as the ‘back-up’ channel.

• The two channels are physically separated within the EEC through a unique circuit mounting board system and exchange data through a data cross-link facility.



CHANNEL A OUTPUT DRIVER


CHANNEL A OUTPUT DRIVER

CROSSLINK

CHANNEL B OUTPUT DRIVER


Also known as P3

Also known as P4.9


EEC ConnectionsEEC Connections

• Two identical, but separate harnesses provide input/output circuits between EEC and the relevant sensor/control actuator, and the aircraft interface.

• Harnesses are ‘keyed’.

• Pressure signals are sensed by transducers within the EEC, which are then converted into digital signals which are supplied independently to both channels.




EEC Connections EEC Connections

• The following pressures are sensed:• Pamb - Ambient air pressure (Fan Case

Sensor).• Pb - Burner pressure (Air Pressure - P3/T3

probe).• P2 - Fan Inlet pressure (P2/T2 probe).• P2.5 - LP Compressor (Booster stage) exit

pressure.• P5 (P4.9) - LP Turbine exhaust pressure

rake.• P12.5 - Fan Outlet pressure (Fan Rake).




P2/T2 Probe


P2.5 Pressure Rake Location


T2.5 Thermocouple Terminal


T2.5 Thermocouple Terminal


P3/T3 Probe


P3/T3 Probe


EEC Connections EEC Connections

• There are eleven electrical connections which have a unique identification ‘J #’.

• Ten are numbered for the two EEC channels.

• One connection ‘J6’ is the ‘Data Entry Plug’ and must remain with the engine, as an engine part.



EEC Control FunctionsEEC Control Functions

• Engine Power Setting or ‘Engine Pressure Ratio’ (EPR).

• Acceleration and Deceleration times.

• Idle speed governing.

• Overspeed limit control (N1 and N2)

• Fuel flow.

• Variable Stator Vane System (VSV)


EEC Control Functions EEC Control Functions

• Compressor Handling Bleed Valves (HP7 & HP10).

• LP Compressor (Booster Stage) Bleed Valve (BSBV).

• Turbine cooling (Stage 10 ‘Make-up’) air system.

• Active Clearance Control (ACC)

• Thrust Reverser



• Oil and Fuel Temperature Management.

• Automatic Engine Starting.

Note! The fuel cut-off command (Engine shut-down) is not controlled by the EEC. This is a command made directly by the ‘Flight Crew’.



Fault Monitoring.

• The EEC has extensive built-in ‘self test’

and ‘fault isolation’ logic.

• This logic operates continuously to

detect and isolate defects in the EEC.


FADEC - General Arrangement



Main EEC/Aircraft InterfacesMain EEC/Aircraft Interfaces

Engine Interface Unit (EIU) x2

• Supply aircraft data to EEC.

• Ensure engine to engine segregation.

• Select aircraft electrical supplies to the EEC.

• Supply data directly to other aircraft systems.


EIU

28

28

28

CFDIUFCU


Air Data Inertial Reference System

(ADIRS)

• Processes ‘pitot’ and ‘static’ pressure inputs.

• Supply air data to other aircraft systems,

including EEC and to the Display Management

Computers (DMC’s)




Flight Warning Computer

(FWC) x2

• Process data and fault annunciation.

• Generate actions necessary for

associated fault.


Display Management Computer

(DMC) x3

• Receive and process data from other

aircraft systems.

• Format and display the data on the six

display units on the flight deck.




Upper ECAM Screen


Lower ECAM Screen



Flight Management and Guidance Computer (FMGC) x2

• Flight Management, Navigation, Performance

Optimisation and Display Management.

• Flight Guidance, Auto Pilot and Autothrust

commands to the EEC.



Additional interfaces with the EEC through the EIU are:

• Spoilers Elevators Computer (SEC).• Landing Gear Control Interface Unit (LGCIU).• Bleed Monitoring Computer (BMC).• Flight Control Unit (FCU).• Centralised Fault Display Interface Unit

(CFDIU).• Multipurpose Control and Display Unit

(MCDU).



Multipurpose Centralised Display Unit (MCDU)


EEC - Data Entry PlugEEC - Data Entry Plug

Located on to ‘Junction 6’ of the EEC.

Provides the EEC with:

• Unique engine data to both Channel ‘A’

and ‘B’.



Data Entry Plug Connection


Data Entry Plug Connection


Data supplied by the Data Entry Plug:

• EPR Modifier (Used to standardise power setting indication)

• Engine Rating (Selected from multiple rating options)

• Engine Serial Number.



Data Entry Plug

Data Entry Plug Lanyard



Who put that up there?


Dummy C-Ducts

Bell Mouthed Intake



• Links coded data inputs through the

EEC by the use of shorting ‘jumper’

leads, which are used to select the plug

pins in a unique combination.

• Can be re-configured as a result of

‘Service Bulletins’ or after engine

overhaul when the EPR modifier code

may need to be changed.


EEC Failures and RedundancyEEC Failures and Redundancy

Improved reliability is achieved

by utilising:

• Dual Sensors.

• Dual Feedback.

• Dual Control Channels.


EEC Failures and RedundancyEEC Failures and Redundancy(Sensors)(Sensors)

• Dual Sensors are used to supply all

EEC inputs, with the exception of

pressures.

• Single pressure transducers within the

EEC provide signals to ‘A’ and ‘B’

channels.


EEC Failures and RedundancyEEC Failures and Redundancy(Dual Control Channels)(Dual Control Channels)

EEC utilises identical software in each of it’s two channels.

• Each channel has an independent:Power supply.Processor.Programme memory and input/output functions.The channel ‘in control’ is decided by the logic,

selecting the healthiest and most capable of control.



Engine Electronic Control Unit


EEC Failures and RedundancyEEC Failures and Redundancy(Dual Selectors)(Dual Selectors)

• Each channel normally uses it’s own input signals, but can use other channel input signal if it recognises faulty or suspect inputs.

• An output fault in one channel may cause a switchover to control from the other channel.

• If faults are experienced in ‘both’ channels, a pre-determined ‘hierarchy selects the more capable channel.

• Loss of both channels or electrical power, the systems are designed to go to ‘fail-safe’ conditions.


5


5


EEC SystemEEC System

Failsafe PositionFailsafe Position• Minimum Fuel Flow Minimum Fuel Flow

Position.Position.• Last Commanded Last Commanded

Position.Position.

• Normal Fuel MeteringNormal Fuel Metering

ComponentFuel Metering Valve Torque

Motor.

Fuel Shut-Off Valve.

Overspeed Valve Solenoid.


Failsafe PositionFailsafe Position

• Valves OpenValves Open

• Valve OpenValve Open


Component

7th Stage Bleed Valves

10th Stage Bleed Valves

LP Compressor (2.5) Bleed Actuator




• Valve Partially Open (44%)Valve Partially Open (44%)

• Valve ClosedValve Closed

Component

Active Clearance Control Unit. (ACC)

Low Pressure ACC

High Pressure ACC




• Vanes OpenVanes Open



Component

Stator Vane Actuator.

Air/Oil Cooler Control Valve

Actuator.

Stage 10 Turbine Cooling

‘Make-up’ Air Valve.



• Failsafe PositionFailsafe Position

• Solenoid De-energised Solenoid De-energised (Mode 4 or 5)(Mode 4 or 5)

• Valve Closed - No return to Valve Closed - No return to tank (Mode 3 or 5)tank (Mode 3 or 5)

Component Fuel Diverter Return

to Tank Valve.

Fuel Diverter Valve.

Fuel Return to Tank Valve.




• Ignition ‘On’Ignition ‘On’

• Heater ‘Off’Heater ‘Off’

ComponentP2/T2 Relay Box

Ignition Relays

Probe Heater Relays




• Reverser ‘Stowed’.Reverser ‘Stowed’.

• Valve ‘Closed’.Valve ‘Closed’.

Component

Thrust Reverser

Control Unit.

Starter Air Valve



EEC Power SuppliesEEC Power Supplies

• The power supplies are normally

provided by a ‘Dedicated Alternator’

mounted on the ‘External Gearbox’.





EEC Power Supplies:EEC Power Supplies:(Dedicated Alternator)(Dedicated Alternator)

• ‘Permanent Magnet’ Alternator.

• 2 sets of independent stator windings.

• Provides 2 independent 3 phase Alternating Current (AC) supplies.

• AC supply ‘rectified’ to 28 volts Direct Current (DC) within the EEC.

• Also provides the N2 (HP Rotor) speed to the EEC.


STATOR

ROTOR


EEC also utilises aircraft power

supplies to operate some engine

systems.

• 115 volts AC 400 hz supply for:

Engine Ignition System.

P2/T2 Probe ‘Anti-icing’ heater.



28 volts DC is required for some specific

functions, which include:

• Thrust Reverser.

• Fuel ‘on/off’.

• Ground Test power for EEC

maintenance.



• Should the Dedicated Alternator fail, the EEC will be supplied with 28 volts DC from the aircraft Bus-bars.

• 28 volts DC from the same source will be used by the EEC during the start sequence until the Dedicated Alternator comes ‘on-line’ at approximately 10% N2.

• Switching of the power supply source is automatically controlled by the EEC.


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Electronic Engine Control