1. FADEC

2. FADEC
• What is FADEC?
• Digital Electronic Controls
• Design Requirements : Modern
Engine Control System
• Why is FADEC Preferred?
• A Backgrounder
• Location of FADEC
• Electronic Aspects of FADEC
• How does FADEC work?
• FADEC : Functions
• FADEC : Essential Features
• FADEC : Infrastructure (Simplified)
• Schematic Diagram
• Advantages & Limitations

3. WHAT IS FADEC?
FADEC: (Full Authority Digital Engine Control
System)
- a digital electronic control system
- able to autonomously control the
engine
- throughout its whole operating
range
- in both normal and fault conditions

4. WHAT IS FADEC?
FADEC: (Full Authority Digital Engine Control
System)
- has a self-monitoring, self-operating,
redundant & fail-safe setup
- comprises of a digital computer
and the other accessories (that control
all the aspects of aircraft engine
performance)

5. WHAT IS FADEC?
FADEC: (Full Authority Digital Engine Control System)
- key system of gas turbine engines
- provides optimum engine efficiency
for a given flight condition
- also controls engine starting and
restarting.

6. WHAT IS FADEC?
FADEC: (Full Authority Digital Engine Control System)
- lowers the work-load of pilots,
- reduces the occurrence of pilot
errors,
- provides for efficient engine
operation.

7. WHAT IS FADEC?
FADEC: (Full Authority Digital Engine Control System)
allows the manufacturer to
-program engine limitations
and
-receive engine health and
maintenance reports.

8. WHAT IS FADEC?
- no form of manual override
available
- places full authority to the control
of operating parameters of the engine
in the hands of the computer.
- if a total FADEC failure occurs, the
engine fails.

9. WHAT IS FADEC?
Note: If the engine is controlled
digitally and electronically but allows
for manual override, it is considered
solely an Electronic Engine Control
(EEC) or Electronic Control Unit (ECU).
An EEC, though a component
of a FADEC, is not by itself FADEC.
When standing alone, the EEC makes
all of the decisions until the pilot
wishes to intervene.

10. DIGITAL ELECTRONIC CONTROL
The benefits of digital electronic
control of mechanical systems are
evident in greater precision and an
ability to measure or predict
performance degradation and incipient
failure.
Typical examples of this are digital
implementations of flight control or fly-
by-wire (FBW) and digital engine
control, or Full-Authority Digital Engine
Control (FADEC).

11. DIGITAL ELECTRONIC CONTROL
Integrated Flight and Propulsion
Control (IFPC) allows closer integration
of the aircraft flight control and engine
control systems.
Flight control systems are virtually all
fly-by-wire (FBW) in the modern fighter
aircraft of today; the benefits being
weight reduction and improved handling
characteristics.

12. DESIGN REQUIREMENTS OF
MODERN ENGINE CONTROL
SYSTEM
• Speed / Accuracy / Ease of Control
(Least Aircrew Workloads)
• Wide Operational Range
• Reliability & Operational Safety
• Low Operating & Maintenance
Costs
• Should Not Add Weight
• Fuel Efficiency
• Dependable Starts

13. WHY IS FADEC PREFERRED?
New engines are adopting FADEC for
-the benefits offered by digital
control,
-improved reliability and
performance,
-weight-reduction and
-other improvements in system
integration and data flow.

14. A BACKGROUNDER
The FADEC systems were first used
in the automotive Industry where it is
well proven.
Now-a-days airlines and the
militaries all over the world
incorporate it on turbine powered
aircraft.
FADECs are made for piston engine
and jet engines both but they differ
in the way of controlling the engine .

15. A BACKGROUNDER
Advanced, intelligent & robust
propulsion controls are critical for
improving the safety and
maintainability of future propulsion
systems.
Propulsion system reliability is
considered to be critical for aircraft
survival. Hence, FADEC systems came
into being.

16. A BACKGROUNDER
FADEC is now common on many
engines.
Semiconductor and equipment
cooling technology has advanced
so that control units can now be
mounted on the engine and still
provide highly reliable operation
for long periods.

17. A BACKGROUNDER
Developing and implementing modern
intelligent engine systems requires the
introduction of numerous sensors,
actuators and processors to provide
the advanced functionality.

18. A BACKGROUNDER
The application of artificial
intelligence and knowledge-
based system for both
software and hardware
provides the foundation for
building the intelligent
control system of the future.

19. A BACKGROUNDER
With time, control systems became
more sophisticated with the
introduction of additional engine
condition sensors and multiple
servo-loops.

20. A BACKGROUNDER
The task of handling engines was
eased by the introduction of
electronic control in the form of
magnetic amplifiers in early civil and
military aircraft.

21. A BACKGROUNDER
The magnetic amplifiers allowed
engines to be stabilized at any speed
in the throttle range by introducing a
servo-loop with engine exhaust gas
temperature as a measure of engine
speed and an analogue fuel valve to
control fuel flow.

22. A BACKGROUNDER
Transistors, integrated circuits and
high temperature semi-conductors
have all played a part in the evolution
of control systems from range
temperature control through to full
digital engine control systems.

23. A BACKGROUNDER
This allowed the pilot to accelerate
and decelerate the engine while the
control system limited fuel flows to
prevent over- speeds or excessive
temperatures.

24. A BACKGROUNDER
With modern FADEC systems there are
no mechanical control rods or
mechanical reversions, and the pilot
can perform carefree handling of the
engine throughout the flight envelope.

25. A BACKGROUNDER
On modern aircraft the engine is
supervised by a computer to allow the
pilot to operate at maximum
performance in a combat aircraft or at
optimum fuel economy in a passenger
carrying aircraft.

26. A BACKGROUNDER
Today, each FADEC is unique and
therefore is expensive to develop,
produce, maintain, and upgrade for its
particular application.

27. A BACKGROUNDER
In the future, it is desired to establish
a universal or common standard for
engine controls and accessories. This
will significantly reduce the high
development and support costs
across platforms.

28. LOCATION OF FADEC
FADEC is normally located on the
engine fan casing. Therefore, FADEC
cooling is difficult.

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

30. ELECTRONIC ASPECTS OF FADEC
Modern ECUs use a microprocessor
which can process the inputs from the
engine sensors in real time. An
electronic control unit contains the
hardware and software (firmware).

31. ELECTRONIC ASPECTS: FADEC
The hardware consists of electronic
components on a printed circuit board
(PCB), ceramic substrate or a thin
laminate substrate. The main
component on this circuit board is a
microcontroller chip (CPU).

32. ELECTRONIC ASPECTS : FADEC
The software is stored in the
microcontroller or other chips on the
PCB, typically in EPROMs or flash
memory so the CPU can be re-
programmed by uploading updated
code or replacing chips. This is also
referred to as an Electronic Engine
Management System (EMS).

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

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

35. HOW DOES FADEC WORK?
Engine operating parameters such as
fuel flow, stator vane position, bleed
valve position and others are
computed from this data and applied
as appropriate.

36. HOW DOES FADEC WORK?
For example, to avoid exceeding a
certain engine temperature, the
FADEC can be programmed to
automatically take the necessary
measures without pilot intervention.
The inputs are received by the EEC
and analyzed up to 70 times per
second.

37. HOW DOES FADEC WORK?
FADEC computes the appropriate thrust
settings and applies them.
During flight, small changes in
operation are constantly being made to
maintain efficiency.
Maximum thrust is available for
emergency situations if the throttle is
advanced to full, but remember,
limitations can’t be exceeded.

38. HOW DOES FADEC WORK?
Another new feature of the FADEC
system is the ability to record the last
900 hours of flight.
With readings taken every second, this
stored information can be used to
diagnose problem areas as well as
review recent flight history.

39. FADEC : FUNCTIONS
AIRFRAME ENGINE CONTROL
COMMUNICATION
REPORT ACQUIRE
ENGINE STATUS SENSOR DATA
RECEIVE ENGINE PROCESS
POWER COMMAND
FADEC CONTROL LAWS
COMMAND
ACTUATORS
ENGINE HEALTH
MONITORING
DIAGNOSTIC
PROGNOSTIC
ADAPTIVE

40. FADEC : ESSENTIAL
FEATURES
- Control & Monitoring of Engine Operations
- Dual Channels & Redundancy
- Engine Life Monitoring
- Record of Engine Performance Parameters
- Automated Troubleshooting
- Memory Read or Recall of Engine Data
- Control of Common Engine Problems
- Display of Warnings
- Adaptation
- Isochronous Idle Speed

41. FADEC
:INFRASTRUCTURE
CONTROL OPERATIONS IN GAS TURBINE
ENGINES

42. FADEC:
INFRASTRUCTURE
CONTROL OPERATIONS IN GAS TURBINE
ENGINES
- Air Control (Compressor Entry)
- Fuel Control (Main / AB / Starting System)
- Starting & Ignition Control
- Lubrication Control
- Surge Control (Through Bleed Valve)
- Thrust Control (Through Exhaust Nozzle)
- Vibration Control (Through Air / Fuel Control)

43. FADEC: INFRASTRUCTURE
SAMPLE CHAIN OF CONTROL (MECH.)
OPERATION
GEAR DRIVEN WORKING FLUID ACTUATED
MECHANICAL PUMP FROM ASSEMBLY
ENGINE / AIRCRAFT
ELECTRO-HYDRO-MECHNICAL
MECHANICAL
CONTROL UNIT
ACTUATORS
SERVO POSITION POSITION
POSITION SOLENOID
ACTUATING
SENSORS VALVES SENSOR-1 SENSOR-2
MOTORS
FADEC COMPUTER
AIRCRAFT COMPUTER COCKPIT

44. FADEC : INFRASTRUCTURE
SAMPLE CHAIN OF CONTROL (ELECT.)
OPERATION
MECHANICAL
ACTUATORS
ELECTRO-HYDRO-MECHNICAL
CONTROL UNIT POSITION POSITION
SERVO SENSOR-1 SENSOR-2
POSITION SOLENOID
ACTUATING
SENSORS VALVES
MOTORS
FADEC
COMPUTER
PILOT’s THROTTLE
VARIOUS INPUTS IN COCKPIT
FROM AIRCRAFT
POWER DISPLAY PANEL
SUPPLY IN COCKPIT
VARIOUS INPUTS FROM /
COMMANDS TO ENGINE

45. FADEC: INFRASTRUCTURE
HARDWARE:
- Dual Power Supply
- FADEC Computer (With Logic Circuit PCBs &
Programmed / Programmable Memory)
- A Set of Servo Actuating Motors / Solenoid Valves /
Position Sensors (for every System Control Unit)
- Dual Position Sensors for Actuators (of every
System)
- A Set of Electrical Harnesses (for every System)
- Display Panel with Indicators / Warning Lights (in
Cockpit)
- Multiple Engine RPM, Pressure Sensors &
Thermocouples
- Pilot’s Throttle

46. FADEC :
INFRASTRUCTURE
SOFTWARE:
- EPR Schedules (For Thrust, over Entire
Range of Engine Operation Without FADEC
Computer Failure)
- N Schedules (For Thrust as per Pilot’s
Throttle, Engine Operation in case of Limited
FADEC Computer Functionality)
Note: In case of certain degree of FADEC
failure, there is an automatic mode switch-
over from EPR to N rating. However, if the
failure disappears, the pilot can reset the
mode to switch-back to EPR mode.

47. FADEC: INFRASTRUCTURE
INPUTS:
From Aircraft.
- Ambient Temperature
- Altitude
- Mach Number
- Angle of Attack
- Impact Pressure
- Landing Gear Position
- Missile / Rocket Firing Signals etc.

48. FADEC: INFRASTRUCTURE
INPUTS:
From Engine.
- Throttle Lever Position
- RPM
- Turbine Outlet / Exhaust Gas
Temperature
- Exhaust Nozzle Area
- Fan Duct Flaps Position
- Bearing Temperatures
- Engine Vibration
- Engine Pressures

49. FADEC: INFRASTRUCTURE
SIMPLIFIED FADEC ARCHITECTURE
FADEC LANE-A FADEC
LANE-A
FADEC MONITOR
LANE-A
CONTROL
ENGINE ENGINE
THRUST FADEC LANE-B FADEC FUEL
DEMAND LANE-B DEMAND
FADEC MONITOR
LANE-B
CONTROL

50. FADEC: INFRASTRUCTURE
SIMPLIFIED FADEC ARCHITECHTURE
This simplified architecture is typical
of
many dual-channel FADECs.
There are two independent lanes: Lane
A
and Lane B.

51. FADEC: INFRASTRUCTURE
SIMPLIFIED FADEC ARCHITECHTURE
Each lane comprises a Command
and Monitor portion, which are
interconnected for cross monitoring
purposes, and undertakes the task
of metering the fuel flow to the
engine in accordance with the
necessary control laws to satisfy the
flight crew thrust command.

52. FADEC: INFRASTRUCTURE
SIMPLIFIED FADEC ARCHITECHTURE
The analysis required to decide
upon the impact of certain failures
in conjunction with others, requires
a Markov model in order to be able
to understand the dependencies.

53. FADEC : INFRASTRUCTURE
MARKOV ANALYSIS MODEL
•By using this model the effects of
interrelated failures can be
examined.
•The model has a total of 16 states as
shown by the number in the bottom
right-hand corner of the appropriate
box.

54. FADEC : INFRASTRUCTURE
MARKOV ANALYSIS MODEL
•Each box relates to the serviceability
state of the Lane A Command (Ca) and
Monitor (Ma) channels and Lane B
Command (Cb) and Monitor (Mb)
channels.

55. FADEC : INFRASTRUCTURE
MARKOV ANALYSIS MODEL
•These range from the fully serviceable
state in box 1 through a series of failure
conditions to the totally failed state in box
16.
•Clearly most normal operating conditions
are going to be in the left-hand region of
the model.

56. FADEC :
INFRASTRUCTURE
MARKOV MODEL ANALYSIS
CaMa .CbMb 6
Ca Ma.CbMb 2 Ca Ma. Cb Mb 7 CaMa . Cb Mb 12
Ca Ma .CbMb 3 Ca Ma.Cb Mb 8 CaMa .Cb Mb 13
CaMa.CbMb 1 CaMa . CbMb 16
CaMa. Cb Mb 4 Ca Ma . Cb Mb 9 Ca Ma. CbMb 14
CaMa.Cb Mb 5 Ca Ma .Cb Mb 10 Ca Ma . CbMb 15
CaMa. CbMb 11
NO FAILURE 1 FAILURE 2 FAILURES 3
FAILURES 4 FAILURES
DISPACHABLE CONTROLLABLE ENGINE
ENGINE ENGINE SHUT-DOWN

57. FADEC:
INFRASTRUCTURE
Concentrating on the left-hand side of the
model it can be seen that the fully
serviceable state in box 1 can migrate to any
one of six states:
– Failure of Command channel A results in
state 2 being reached.
– Failure of Monitor channel A results in
state 3 being reached.
– Failure of Command channel B results in
state 4 being reached.
– Failure of Monitor channel B results in
state 5 being reached.
– Failure of the cross-monitor between
Command A and Monitor A results in both
being lost simultaneously and reaching
state 6.
– Failure of the cross-monitor between
Command B and Monitor B results in both
being lost simultaneously and reaching
state 11.

58. FADEC:
INFRASTRUCTURE
All of these failure states result in an
engine which may still be controlled by
the FADEC. However, further failures
beyond this point may result in an
engine which may not be controllable
either because both control channels
are inoperative or because the ‘good’
control and monitor lanes are in
opposing channels or worse.

59. FADEC:
INFRASTRUCTURE
The model shown above is constructed
according to the following rules: an
engine may be dispatched as a ‘get-
you-home’ measure provided that only
one monitor channel has failed.
This means that states 3 and 5 are
dispatchable: but not states 2, 4, 6, or
11 as subsequent failures could result
in engine shut-down.

60. FADEC: ESSENTIAL
FEATURES
MILITARY / TRANSPORT AIRCRAFT
- Compressor Entry Guide Vanes
Control (For LP Compressor & HP
Compressor)
- Main Fuel Control
- AB Fuel Control (For Core & Fan AB)
- Starting Fuel Control & Ignition
Control
- Bleed Valve Control & Fan Duct
Flaps Control
- Exhaust Nozzle Control

61. FADEC : SCHEMATIC DIAGRAM
LP COMPRESSOR
STARTING AIR EGV CONTROL
&
IGNITION HP COMPRESSOR
CONTROL AIR EGV CONTROL
POWER MAIN FUEL
SUPPLY CONTROL
CORE AB FUEL
CONTROL
EECU
FADEC FAN AB FUEL
AIRCRAFT CONTROL
COMPUTER
EXHAUST NOZZLE
CONTROL
FAN DUCT FLAPS
CONTROL
PILOT BLEED VALVE
IN CONTROL
COCKPIT

62. CENTRALIZED CONTROL ARCHITECTURE
Each function resides within the FADECControl unique point-to-
Centralized Engine and uses
point analog connections to system effectors.
Sensor
electronics Sensor_1
Sensor
electronics
Sensor_2
Communication
Sensor
Communication electronics
Sensor_ j
CPU /
BUS
Memory
Actuation Actuator_n
electronics
Power Actuation Actuator_2
electronics
Actuation
electronics Actuator_1
FADEC

63. DISTRIBUTED CONTROL ARCHITECTURE
Functions are distributed outside of the Control
Centralized Engine FADEC and communicate
via a common interface standard.
Sensor
electronics Sensor_1
Sensor
electronics Sensor_2
Communication
Communication Sensor
electronics Sensor_ j
CPU /
Memory
BUS
Actuation
electronics Actuator_n
Actuation
Power electronics Actuator_2
Actuation
electronics Actuator_1
FADEC

64. FADEC : ADVANTAGES
- Reduced Aircrew Workload.
- Improved Fuel Efficiency up to
15% (Due to faster, Accurate
Engine Control no trimming is
required).
- Reduced Aircraft Weight and
Engine Size (Due to Absence of
Heavy Mechanical Assemblies,
No Scattering of Pipelines &
Electrical Wirings).
- Enhanced Engine Life (Due to
Engine Operation in Safer /
Mean Range).
- Improved Reliability (Due to

65. FADEC : ADVANTAGES
- Minimum Maintenance due to On
Board Computer Guided
Troubleshooting (Aircraft
can return to Flying at the
Earliest).
- Isochronous Idle speed leads to
Smoother Engine Starts.

66. FADEC : ADVANTAGES
- Maximum Performance in a
combat aircraft or at Optimum
Fuel Economy in a Transport
Aircraft are possible after
necessary Adaptation /
Programming of FADEC
Computer.
- Auto-testing removes the need
for test-running the engine after
minor maintenance work
( Resulting in annual savings of

67. FADEC : LIMITATIONS
- Pilot can not override the
FADEC Control.
- In the event of complete FADEC
Failure, pilot left with no other
option than having to fly with
least performance, just
sufficient to land safely. (This
limitation has been removed in
modern transport aircraft by
having two FADEC Computers.)

69. FADEC: ANY QUESTION
?