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Aircraft with fly-by-wire flight controls require computer controlled flight control modes that are capable of determining the operational mode (computational law) of the aircraft. A reduction of electronic flight control can be caused by the failure of a computational device, such as the flight control computer or an information providing device, such as the ADIRU. Electronic flight control systems (EFCS) also provide augmentation in normal flight, such as increased protection of the aircraft from overstress or providing a more comfortable flight for passengers by recognizing and correcting for turbulence and providing yaw damping. Two aircraft manufacturers produce commercial passenger aircraft with primary flight computers that can perform under different flight control modes (or laws). The most well-known are the ''normal'', ''alternate'', ''direct'' and ''mechanical laws'' of the Airbus A320-A380.〔 Boeing's fly-by-wire system is used in the Boeing 777, Boeing 787 Dreamliner and Boeing 747-8.〔〔(【引用サイトリンク】title=Avionics Magazine :: Boeing 787: Integration’s Next Step )〕 These newer aircraft use electronic control systems to increase safety and performance while saving aircraft weight. These electronic systems are lighter than the old mechanical systems and can also protect the aircraft from overstress situations, allowing designers to reduce over-engineered components, which further reduces the aircraft's weight. ==Flight control laws (Airbus)== Airbus aircraft designs after the A300/A310 are almost completely controlled by fly-by-wire equipment. These newer aircraft, including the A320, A330, A340, A350 and A380 operate under Airbus flight control laws. The flight controls on the Airbus A330, for example, are all electronically controlled and hydraulically activated. Some surfaces, such as the rudder, can also be mechanically controlled. In normal flight, the computers act to prevent excessive forces in pitch and roll.〔 The aircraft is controlled by three primary control computers (captain's, first officer's, and standby) and two secondary control computers (captain's and first officer's). In addition there are two flight control data computers (FCDC) that read information from the sensors, such as air data (airspeed, altitude). This is fed along with GPS data, into three redundant processing units known as air data inertial reference units (ADIRUs) that act both as an air data reference and inertial reference. ADIRUs are part of the air data inertial reference system, which, on the Airbus is linked to eight air data modules: three are linked to pitot tubes and five are linked to static sources. Information from the ADIRU is fed into one of several flight control computers (primary and secondary flight control). The computers also receive information from the control surfaces of the aircraft and from the pilots aircraft control devices and autopilot. Information from these computers is sent both to the pilot's primary flight display and also to the control surfaces. There are four named flight control laws, however ''alternate law'' consists of two modes, ''alternate law 1'' and ''alternate law 2''. Each of these modes have different sub modes: ground mode, flight mode and flare, plus a back-up ''mechanical law''.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「flight control modes」の詳細全文を読む スポンサード リンク
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