A full authority digital engine (or electronics) control (FADEC) is a system consisting of a digital computer, called an "electronic engine controller" (EEC) or "engine control unit" (ECU), and its related accessories that control all aspects of aircraft engine performance. FADECs have been produced for both piston engines and jet engines.[1]
The goal of any engine control system is to allow the engine to perform at maximum efficiency for a given condition. Originally, engine control systems consisted of simple mechanical linkages connected physically to the engine. By moving these levers the pilot or the flight engineer could control fuel flow, power output, and many other engine parameters. The Kommandogerät mechanical/hydraulic engine control unit for Germany's BMW 801 piston aviation radial engine of World War II was just one notable example of this in its later stages of development.[2] This mechanical engine control was progressively replaced first by analog electronic engine control and, later, digital engine control.
Analog electronic control varies an electrical signal to communicate the desired engine settings. The system was an evident improvement over mechanical control but had its drawbacks, including common electronic noise interference and reliability issues. Full authority analogue control was used in the 1960s and introduced as a component of the Rolls-Royce/Snecma Olympus 593 engine of the supersonic transport aircraft Concorde.[3] However, the more critical inlet control was digital on the production aircraft.[4]
True full authority digital engine controls have no form of manual override available, placing full authority over the operating parameters of the engine in the hands of the computer. If a total FADEC failure occurs, the engine fails. If the engine is controlled digitally and electronically but allows for manual override, it is considered solely an EEC or 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.
FADEC works by receiving multiple input variables of the current flight condition including air density, throttle lever position, engine temperatures, engine pressures, and many other parameters. The inputs are received by the EEC and analyzed up to 70 times per second. Engine operating parameters such as fuel flow, stator vane position, air bleed valve position, and others are computed from this data and applied as appropriate. FADEC also controls engine starting and restarting. The FADEC's basic purpose is to provide optimum engine efficiency for a given flight condition.
FADEC not only provides for efficient engine operation, it also allows the manufacturer to program engine limitations and receive engine health and maintenance reports. For example, to avoid exceeding a certain engine temperature, the FADEC can be programmed to automatically take the necessary measures without pilot intervention.
Safety
With the operation of the engines relying on automation, safety is a great concern. Redundancy is provided in the form of two or more separate but identical digital channels. Each channel may provide all engine functions without restriction. FADEC also monitors a variety of data coming from the engine subsystems and related aircraft systems, providing for fault tolerant engine control.
Engine control problems simultaneously causing loss of thrust on up to three engines have been cited as causal in the crash of an Airbus A400M aircraft at Seville Spain on 9 May 2015. Airbus Chief Strategy Officer Marwan Lahoud confirmed on 29 May that incorrectly installed engine control software caused the fatal crash. "There are no structural defects [with the aircraft], but we have a serious quality problem in the final assembly."[7]
Applications
A typical civilian transport aircraft flight may illustrate the function of a FADEC. The flight crew first enters flight data such as wind conditions, runway length, or cruise altitude, into the flight management system (FMS). The FMS uses this data to calculate power settings for different phases of the flight. At takeoff, the flight crew advances the throttle to a predetermined setting, or opts for an auto-throttle takeoff if available. The FADECs now apply the calculated takeoff thrust setting by sending an electronic signal to the engines; there is no direct linkage to open fuel flow. This procedure can be repeated for any other phase of flight.[citation needed]
In flight, small changes in operation are constantly made to maintain efficiency. Maximum thrust is available for emergency situations if the throttle is advanced to full, but limitations can not be exceeded; the flight crew has no means of manually overriding the FADEC.[citation needed]
Automatic engine protection against out-of-tolerance operations
Safer as the multiple channel FADEC computer provides redundancy in case of failure
Care-free engine handling, with guaranteed thrust settings
Ability to use single engine type for wide thrust requirements by just reprogramming the FADECs
Provides semi-automatic engine starting
Better systems integration with engine and aircraft systems
Can provide engine long-term health monitoring and diagnostics
Number of external and internal parameters used in the control processes increases by one order of magnitude
Reduces the number of parameters to be monitored by flight crews
Due to the high number of parameters monitored, the FADEC makes possible "Fault Tolerant Systems" (where a system can operate within required reliability and safety limitation with certain fault configurations)
Saves weight
Disadvantages
Full authority digital engine controls have no form of manual override available, placing full authority over the operating parameters of the engine in the hands of the computer. (see note)
If a total FADEC failure occurs, the engine fails. (see note)
Upon total FADEC failure, pilots have no manual controls for engine restart, throttle, or other functions. (see note)
Single point of failure risk can be mitigated with redundant FADECs (assuming that the failure is a random hardware failure and not the result of a design or manufacturing error, which may cause identical failures in all identical redundant components). (see note)
High system complexity compared to hydromechanical, analogue or manual control systems
High system development and validation effort due to the complexity
Whereas in crisis (for example, imminent terrain contact), a non-FADEC engine can produce significantly more than its rated thrust, a FADEC engine will always operate within its limits. (see note)
Note: Most modern FADEC controlled aircraft engines (particularly those of the turboshaft variety) can be overridden and placed in manual mode, effectively countering most of the disadvantages on this list. Pilots should be very aware of where their manual override is located, because inadvertent engagement of the manual mode can lead to an overspeed of the engine.[contradictory]
Requirements
Engineering processes must be used to design, manufacture, install and maintain the sensors which measure and report flight and engine parameters to the control system itself.
Formal systems engineering processes are often used in the design, implementation and testing of the software used in these safety-critical control systems. This requirement led to the development and use of specialized software such as model-based systems engineering (MBSE) tools. The application development toolset SCADE (from Ansys) (not to be confused with the application category SCADA) is an example of an MBSE tool and has been used as part of the development of FADEC systems.
Research
NASA has analyzed a distributed FADEC architecture rather than the current centralized one, specifically for helicopters. Greater flexibility and lower life cycle costs are likely advantages of distribution.[8]
^(PDF). Pilot's Handbook of Aeronautical Knowledge. Federal Aviation Administration. 2008. pp. 6–19. Archived from the original (PDF) on 2013-12-10. Retrieved 2013-12-18.
^Gunston, Bill (1989). World Encyclopedia of Aero Engines. Cambridge, UK: Patrick Stephens Ltd. p. 26. ISBN1-85260-163-9.
^Pratt, Roger W (2000). Flight Control Systems: Practical Issues In Design and Implementation. Institute of Electrical Engineers. p. 12. ISBN0852967667.
^Owen, Kenneth (2001). Concorde: Story of a Supersonic Pioneer. Science Museum. p. 69. ISBN978-1-900747-42-4.
Title 14 CFR: Federal Aviation Regulations. FAA. 2007-03-10.
External links
Harrier flies with digitally controlled Pegasus - a 1982 article in Flight International magazine
Active-control engines a 1988 Flight International article on FADEC engines
January 21, 2023
fadec, full, authority, digital, engine, electronics, control, system, consisting, digital, computer, called, electronic, engine, controller, engine, control, unit, related, accessories, that, control, aspects, aircraft, engine, performance, have, been, produc. A full authority digital engine or electronics control FADEC is a system consisting of a digital computer called an electronic engine controller EEC or engine control unit ECU and its related accessories that control all aspects of aircraft engine performance FADECs have been produced for both piston engines and jet engines 1 FADEC for piston engine Contents 1 History 2 Function 2 1 Safety 2 2 Applications 3 Advantages 4 Disadvantages 5 Requirements 6 Research 7 See also 8 References 9 External linksHistory EditThe goal of any engine control system is to allow the engine to perform at maximum efficiency for a given condition Originally engine control systems consisted of simple mechanical linkages connected physically to the engine By moving these levers the pilot or the flight engineer could control fuel flow power output and many other engine parameters The Kommandogerat mechanical hydraulic engine control unit for Germany s BMW 801 piston aviation radial engine of World War II was just one notable example of this in its later stages of development 2 This mechanical engine control was progressively replaced first by analog electronic engine control and later digital engine control Analog electronic control varies an electrical signal to communicate the desired engine settings The system was an evident improvement over mechanical control but had its drawbacks including common electronic noise interference and reliability issues Full authority analogue control was used in the 1960s and introduced as a component of the Rolls Royce Snecma Olympus 593 engine of the supersonic transport aircraft Concorde 3 However the more critical inlet control was digital on the production aircraft 4 Digital electronic control followed In 1968 Rolls Royce and Elliott Automation in conjunction with the National Gas Turbine Establishment worked on a digital engine control system that completed several hundred hours of operation on a Rolls Royce Olympus Mk 320 5 In the 1970s NASA and Pratt and Whitney experimented with their first experimental FADEC first flown on an F 111 fitted with a highly modified Pratt amp Whitney TF30 left engine The experiments led to Pratt amp Whitney F100 and Pratt amp Whitney PW2000 being the first military and civil engines respectively fitted with FADEC and later the Pratt amp Whitney PW4000 as the first commercial dual FADEC engine The first FADEC in service was the Rolls Royce Pegasus engine developed for the Harrier II by Dowty and Smiths Industries Controls 6 Function EditTrue full authority digital engine controls have no form of manual override available placing full authority over the operating parameters of the engine in the hands of the computer If a total FADEC failure occurs the engine fails If the engine is controlled digitally and electronically but allows for manual override it is considered solely an EEC or 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 FADEC works by receiving multiple input variables of the current flight condition including air density throttle lever position engine temperatures engine pressures and many other parameters The inputs are received by the EEC and analyzed up to 70 times per second Engine operating parameters such as fuel flow stator vane position air bleed valve position and others are computed from this data and applied as appropriate FADEC also controls engine starting and restarting The FADEC s basic purpose is to provide optimum engine efficiency for a given flight condition FADEC not only provides for efficient engine operation it also allows the manufacturer to program engine limitations and receive engine health and maintenance reports For example to avoid exceeding a certain engine temperature the FADEC can be programmed to automatically take the necessary measures without pilot intervention Safety Edit With the operation of the engines relying on automation safety is a great concern Redundancy is provided in the form of two or more separate but identical digital channels Each channel may provide all engine functions without restriction FADEC also monitors a variety of data coming from the engine subsystems and related aircraft systems providing for fault tolerant engine control Engine control problems simultaneously causing loss of thrust on up to three engines have been cited as causal in the crash of an Airbus A400M aircraft at Seville Spain on 9 May 2015 Airbus Chief Strategy Officer Marwan Lahoud confirmed on 29 May that incorrectly installed engine control software caused the fatal crash There are no structural defects with the aircraft but we have a serious quality problem in the final assembly 7 Applications Edit A typical civilian transport aircraft flight may illustrate the function of a FADEC The flight crew first enters flight data such as wind conditions runway length or cruise altitude into the flight management system FMS The FMS uses this data to calculate power settings for different phases of the flight At takeoff the flight crew advances the throttle to a predetermined setting or opts for an auto throttle takeoff if available The FADECs now apply the calculated takeoff thrust setting by sending an electronic signal to the engines there is no direct linkage to open fuel flow This procedure can be repeated for any other phase of flight citation needed In flight small changes in operation are constantly made to maintain efficiency Maximum thrust is available for emergency situations if the throttle is advanced to full but limitations can not be exceeded the flight crew has no means of manually overriding the FADEC citation needed Advantages EditBetter fuel efficiency Automatic engine protection against out of tolerance operations Safer as the multiple channel FADEC computer provides redundancy in case of failure Care free engine handling with guaranteed thrust settings Ability to use single engine type for wide thrust requirements by just reprogramming the FADECs Provides semi automatic engine starting Better systems integration with engine and aircraft systems Can provide engine long term health monitoring and diagnostics Number of external and internal parameters used in the control processes increases by one order of magnitude Reduces the number of parameters to be monitored by flight crews Due to the high number of parameters monitored the FADEC makes possible Fault Tolerant Systems where a system can operate within required reliability and safety limitation with certain fault configurations Saves weightDisadvantages EditFull authority digital engine controls have no form of manual override available placing full authority over the operating parameters of the engine in the hands of the computer see note If a total FADEC failure occurs the engine fails see note Upon total FADEC failure pilots have no manual controls for engine restart throttle or other functions see note Single point of failure risk can be mitigated with redundant FADECs assuming that the failure is a random hardware failure and not the result of a design or manufacturing error which may cause identical failures in all identical redundant components see note High system complexity compared to hydromechanical analogue or manual control systems High system development and validation effort due to the complexity Whereas in crisis for example imminent terrain contact a non FADEC engine can produce significantly more than its rated thrust a FADEC engine will always operate within its limits see note Note Most modern FADEC controlled aircraft engines particularly those of the turboshaft variety can be overridden and placed in manual mode effectively countering most of the disadvantages on this list Pilots should be very aware of where their manual override is located because inadvertent engagement of the manual mode can lead to an overspeed of the engine contradictory Requirements EditEngineering processes must be used to design manufacture install and maintain the sensors which measure and report flight and engine parameters to the control system itself Formal systems engineering processes are often used in the design implementation and testing of the software used in these safety critical control systems This requirement led to the development and use of specialized software such as model based systems engineering MBSE tools The application development toolset SCADE from Ansys not to be confused with the application category SCADA is an example of an MBSE tool and has been used as part of the development of FADEC systems Research EditNASA has analyzed a distributed FADEC architecture rather than the current centralized one specifically for helicopters Greater flexibility and lower life cycle costs are likely advantages of distribution 8 See also EditAcronyms and abbreviations in avionicsReferences Edit Chapter 6 Aircraft Systems PDF Pilot s Handbook of Aeronautical Knowledge Federal Aviation Administration 2008 pp 6 19 Archived from the original PDF on 2013 12 10 Retrieved 2013 12 18 Gunston Bill 1989 World Encyclopedia of Aero Engines Cambridge UK Patrick Stephens Ltd p 26 ISBN 1 85260 163 9 Pratt Roger W 2000 Flight Control Systems Practical Issues In Design and Implementation Institute of Electrical Engineers p 12 ISBN 0852967667 Owen Kenneth 2001 Concorde Story of a Supersonic Pioneer Science Museum p 69 ISBN 978 1 900747 42 4 1968 2110 Flight Archive Gunston 1990 Avionics The story and technology of aviation electronics Patrick Stephens Ltd Wellingborough UK page needed ISBN 1 85260 133 7 Chirgwin Richard 2015 05 31 Airbus confirms software brought down A400M transport plane The Register Retrieved 2016 02 20 Distributed Engine Control PDF Nasa gov Archived from the original PDF on 2016 12 22 Safran Electronics Canada FADEC and EEC Archived from the original on 2013 01 15 Retrieved 2010 04 30 Hispano Suiza Digital Engine Control Archived from the original on 2007 09 28 Retrieved 2007 03 09 Moren Chuck Interview with student FADEC Embry Riddle Aeronautical University Daytona Beach 2007 03 13 Title 14 CFR Federal Aviation Regulations FAA 2007 03 10 External links EditHarrier flies with digitally controlled Pegasus a 1982 article in Flight International magazine Active control engines a 1988 Flight International article on FADEC engines Retrieved from https en wikipedia org w index php title FADEC amp oldid 1129593081, wikipedia, wiki, book, books, library,
