Digital Engine Control System

© International Aero Engines Inc 2000
Electronic Engine Control
EXIT

Full Authority Digital Engine
Full Authority Digital Engine
Control System
Control System
(F.A.D.E.C.)
(F.A.D.E.C.)

Introduction
Introduction
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.

Introduction
Introduction
Output devices include:
• Solenoids.
• Fuel Servo Operated Actuators.
• Pnuematic Servo Operated Devices.
• Dual Electrical Harness.

Engine 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.

EEC Mounting point

(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 Description
EEC 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.

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 Connections
EEC 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

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 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)

• 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 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
CFDIU
FCU

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
EEC -
- Data Entry Plug
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

EEC
EEC -
- Data Entry Plug
Data Entry Plug
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

EEC
EEC -
- Data Entry Plug
Data Entry Plug
• 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 Redundancy
Improved reliability is achieved
by utilising:
• Dual Sensors.
• Dual Feedback.
• Dual Control Channels.

(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.

(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

(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

EEC System
EEC System
Failsafe Position
Failsafe Position
•
• Minimum Fuel Flow
Minimum Fuel Flow
Position.
Position.
•
• Last Commanded
Last Commanded
Position.
Position.
•
• Normal Fuel Metering
Component
Fuel Metering Valve Torque
Motor.
Fuel Shut-Off Valve.
Overspeed Valve Solenoid. Normal Fuel Metering

EEC System
EEC System
Failsafe Position
Failsafe Position
•
• Valves Open
Valves Open
•
• Valve Open
Valve Open
•
• Valve Open
Valve Open
Component
7th Stage Bleed Valves
10th Stage Bleed Valves
LP Compressor (2.5) Bleed Actuator

EEC System
EEC System
Failsafe Position
Failsafe Position
•
• Valve Partially Open (44%)
Valve Partially Open (44%)
•
• Valve Closed
Valve Closed
Component
Active Clearance Control Unit. (ACC)
Low Pressure ACC
High Pressure ACC

EEC System
EEC System
Failsafe Position
Failsafe Position
•
• Vanes Open
Vanes Open
•
• Valve Open
Valve Open
•
• Valve Open
Valve Open
Component
Stator Vane Actuator.
Air/Oil Cooler Control Valve
Actuator.
Stage 10 Turbine Cooling
‘Make-up’ Air Valve.

EEC System
EEC System
•
• Failsafe Position
Failsafe Position
•
• Solenoid De
Solenoid De-
-energised
energised
(Mode 4 or 5)
(Mode 4 or 5)
•
• Valve Closed
Valve Closed -
- No return to
No return to
tank (Mode 3 or 5)
Component
Fuel Diverter Return
to Tank Valve.
Fuel Diverter Valve.
Fuel Return to Tank
Valve. tank (Mode 3 or 5)

EEC System
EEC System
Failsafe Position
Failsafe Position
•
• Ignition
Ignition ‘
‘On
On’
’
•
• Heater
Heater ‘
‘Off
Off’
Component
P2/T2 Relay Box
Ignition Relays
Probe Heater Relays ’

EEC System
EEC System
Failsafe Position
Failsafe Position
•
• Reverser
Reverser ‘
‘Stowed
Stowed’
’.
.
•
• Valve
Valve ‘
‘Closed
Closed’
’.
Component
Thrust Reverser
Control Unit.
Starter Air Valve .

EEC Power Supplies
EEC 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 Power Supplies
EEC Power Supplies
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.

EEC Power Supplies
EEC Power Supplies
28 volts DC is required for some specific
functions, which include:
• Thrust Reverser.
• Fuel ‘on/off’.
• Ground Test power for EEC
maintenance.

EEC Power Supplies
EEC Power Supplies
• 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.
Exit

Digital Engine Control System

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