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]
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 & Whitney TF30 left engine. The experiments led to Pratt & Whitney F100 and Pratt & Whitney PW2000 being the first military and civil engines, respectively, fitted with FADEC, and later the Pratt & 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]
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True full authority digital engine controls have no form of manual override nor manual controls available, placing full authority over all of 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 to be 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. The term FADEC is often misused for partial digital engine controls, such as those only electronically controlling fuel and ignition.
FADEC works by receiving multiple input variables of the current flight condition including air density, power lever request 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.
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]
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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 power lever 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 power lever is advanced to full, but limitations can not be exceeded; the flight crew has no means of manually overriding the FADEC.[ citation needed ]
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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 ]
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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]
Fly-by-wire (FBW) is a system that replaces the conventional manual flight controls of an aircraft with an electronic interface. The movements of flight controls are converted to electronic signals transmitted by wires, and flight control computers determine how to move the actuators at each control surface to provide the ordered response. It can use mechanical flight control backup systems or use fully fly-by-wire controls.
A turboprop is a turbine engine that drives an aircraft propeller.
The turbofan or fanjet is a type of airbreathing jet engine that is widely used in aircraft propulsion. The word "turbofan" is a combination of the preceding generation engine technology of the turbojet, and a reference to the additional fan stage added. It consists of a gas turbine engine which achieves mechanical energy from combustion, and a ducted fan that uses the mechanical energy from the gas turbine to force air rearwards. Thus, whereas all the air taken in by a turbojet passes through the combustion chamber and turbines, in a turbofan some of that air bypasses these components. A turbofan thus can be thought of as a turbojet being used to drive a ducted fan, with both of these contributing to the thrust.
The Pratt & Whitney PW4000 is a family of dual-spool, axial-flow, high-bypass turbofan aircraft engines produced by Pratt & Whitney as the successor to the JT9D. It was first run in April 1984, was FAA certified in July 1986, and was introduced in June 1987. With thrust ranging from 50,000 to 99,040 lbf, it is used on many wide-body aircraft.
The Pratt & Whitney PW2000, also known by the military designation F117 and initially referred to as the JT10D, is a series of high-bypass turbofan aircraft engines with a thrust range from 37,000 to 43,000 lbf. Built by Pratt & Whitney, they were designed for the Boeing 757. As a 757 powerplant, these engines compete with the Rolls-Royce RB211.
The General Electric/Rolls-Royce F136 was an advanced turbofan engine being developed by General Electric and Rolls-Royce plc for the Lockheed Martin F-35 Lightning II. The two companies stopped work on the project in December 2011 after failing to gather Pentagon support for further development.
The IAE V2500 is a two-shaft high-bypass turbofan engine built by International Aero Engines (IAE) which powers the Airbus A320 family, the McDonnell Douglas MD-90, and the Embraer C-390 Millennium.
The Engine Alliance GP7000 is a turbofan jet engine manufactured by Engine Alliance, a joint venture between General Electric and Pratt & Whitney. It is one of the powerplant options available for the Airbus A380, along with the Rolls-Royce Trent 900.
The General Electric CF6, US military designations F103 and F138, is a family of high-bypass turbofan engines produced by GE Aviation. Based on the TF39, the first high-power high-bypass jet engine, the CF6 powers a wide variety of civilian airliners. The basic engine core also powers the LM2500 and LM6000 marine and power generation turboshafts. It is gradually being replaced by the newer GEnx family.
Hamilton Standard was an American aircraft propeller parts supplier. It was formed in 1929 when United Aircraft and Transport Corporation consolidated Hamilton Aero Manufacturing and Standard Steel Propeller into the Hamilton Standard Propeller Corporation. Other members of United Aircraft included Boeing, United Airlines, Sikorsky and Pratt & Whitney. At the time, Hamilton was the largest manufacturer of aircraft propellers in the world.
A compressor stall is a local disruption of the airflow in the compressor of a gas turbine or turbocharger. A stall that results in the complete disruption of the airflow through the compressor is referred to as a compressor surge. The severity of the phenomenon ranges from a momentary power drop barely registered by the engine instruments to a complete loss of compression in case of a surge, requiring adjustments in the fuel flow to recover normal operation.
The Rolls-Royce Trent 900 is a high-bypass turbofan produced by Rolls-Royce plc to power the Airbus A380, competing with the Engine Alliance GP7000. Initially proposed for the Boeing 747-500/600X in July 1996, this first application was later abandoned but it was offered for the A3XX, launched as the A380 in December 2000. It first ran on 18 March 2003, made its maiden flight on 17 May 2004 on an A340 testbed, and was certified by the EASA on 29 October 2004. Producing up to 374 kN (84,000 lbf), the Trent 900 has the three shaft architecture of the Rolls-Royce Trent family with a 2.95 m (116 in) fan. It has a 8.5–8.7:1 bypass ratio and a 37–39:1 overall pressure ratio.
IAE International Aero Engines AG is a Zürich-registered joint venture aeroengine manufacturing company.
The General Electric YF120, internally designated as GE37, was a variable cycle afterburning turbofan engine designed by General Electric Aircraft Engines in the late 1980s and early 1990s for the United States Air Force's Advanced Tactical Fighter (ATF) program. It was designed to produce maximum thrust in the 35,000 lbf (156 kN) class. Prototype engines were installed in the two competing technology demonstrator aircraft, the Lockheed YF-22 and Northrop YF-23.
A takeoff/go-around switch is a switch on the autothrottle of modern large aircraft, with two modes: takeoff (TO) and go-around (GA). The mode is dependent on the phase of flight; usually, on approach to land, the autopilot will be set to approach mode, therefore if the TO/GA switch is pressed it will activate the go-around mode of the autothrottle (about 90–92% N1, if pressed again, go around thrust will increase to full ; conversely, when takeoff is set on the autopilot, the switch activates takeoff mode of the autothrottle. On Boeing aircraft TO/GA modes are selected by a separate button near the throttle levers, but on Airbus aircraft it is activated by advancing the thrust levers forward to the TO/GA detent.
An autothrottle is a system that allows a pilot to control the power setting of an aircraft's engines by specifying a desired flight characteristic, rather than manually controlling the fuel flow. The autothrottle can greatly reduce the pilots' work load and help conserve fuel and extend engine life by metering the precise amount of fuel required to attain a specific target indicated air speed, or the assigned power for different phases of flight. A/T and AFDS can work together to fulfill the whole flight plan.
S7 Airlines Flight 778(S7778/SBI778) was a scheduled domestic passenger flight from Moscow to Irkutsk, Russia. On 9 July 2006, at 06:44 local time, the Airbus A310-324 aircraft operating the route overran the runway during its landing in Irkutsk. The aircraft failed to stop and crashed through the airport's concrete perimeter fence, struck rows of private garages and burst into flames, killing 125 people.
A fuel control unit is a control system for gas turbine engines.
A flight control mode or flight control law is a computer software algorithm that transforms the movement of the yoke or joystick, made by an aircraft pilot, into movements of the aircraft control surfaces. The control surface movements depend on which of several modes the flight computer is in. In aircraft in which the flight control system is fly-by-wire, the movements the pilot makes to the yoke or joystick in the cockpit, to control the flight, are converted to electronic signals, which are transmitted to the flight control computers that determine how to move each control surface to provide the aircraft movement the pilot ordered.
The General Electric Passport is a turbofan developed by GE Aerospace for large business jets. It was selected in 2010 to power the Bombardier Global 7500/8000, first run on June 24, 2013, and first flown in 2015. It was certified in April 2016 and powered the Global 7500 first flight on November 4, 2016, before its 2018 introduction. It produces 14,000 to 20,000 lbf of thrust, a range previously covered by the General Electric CF34. A smaller scaled CFM LEAP, it is a twin-spool axial engine with a 5.6:1 bypass ratio and a 45:1 overall pressure ratio and is noted for its large one-piece 52 in (130 cm) fan 18-blade titanium blisk.