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? - lowers the work-load of pilots,
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? allows the manufacturer to
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
FADEC

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
FADEC: INFRASTRUCTURE
GEAR DRIVEN
MECHANICAL PUMP
WORKING FLUID
FROM
ENGINE / AIRCRAFT
ACTUATED
ASSEMBLY
MECHANICAL
ACTUATORS
ELECTRO-HYDRO-MECHNICAL
CONTROL UNIT
SERVO
ACTUATING
MOTORS
POSITION
SENSORS
SOLENOID
VALVES
POSITION
SENSOR-1
POSITION
SENSOR-2
FADEC COMPUTER
AIRCRAFT COMPUTER
COCKPIT

44. FADEC : INFRASTRUCTURE
SAMPLE CHAIN OF CONTROL (ELECT.) OPERATION
ELECTRO-HYDRO-MECHNICAL
CONTROL UNIT
MECHANICAL
ACTUATORS
FADEC
COMPUTER
POSITION
SENSOR-1
POSITION
SENSOR-2
SERVO
ACTUATING
MOTORS
POSITION
SENSORS
SOLENOID
VALVES
PILOT’s THROTTLE
IN COCKPIT
VARIOUS INPUTS
FROM AIRCRAFT
POWER
SUPPLY
DISPLAY PANEL
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
MONITOR
FADEC
LANE-A
CONTROL
ENGINE
THRUST
DEMAND
ENGINE
FUEL
DEMAND
FADEC LANE-B
FADEC
LANE-B
MONITOR
FADEC
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
CaMa.CbMb 2
CaMa.CbMb 7
CaMa.CbMb 12
CaMa.CbMb 3
CaMa.CbMb 8
CaMa.CbMb 13
CaMa.CbMb 1
CaMa.CbMb 16
CaMa.CbMb 4
CaMa.CbMb 9
CaMa.CbMb 14
CaMa.CbMb 5
CaMa.CbMb 10
CaMa.CbMb 15
CaMa.CbMb 11
NO FAILURE FAILURE FAILURES FAILURES FAILURES
DISPACHABLE
ENGINE
CONTROLLABLE
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
Lubrication Control & Vibration Control

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

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

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

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 millions of gallon of fuel for the fleet.

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.)

68. SAFE TAKE OFFs & LANDINGs
ALWAYS
FADEC

69. FADEC: ANY QUESTION ?