Thrust Setting
Figure 019
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2 Alpha floor protection
_ Alpha floor protection is part of autothrust function. When the aircraft angle of attack is greater than a threshold depending on the aircraft configuration, the alpha floor condition is reached and the ATS sends an N1 target demand equal to N1 MAX TAKE-OFF. When receiving alpha floor protection signal through ARINC 429 data bus, the FADEC switches N1 target limitation from N1 throttle = f (TLA) to N1 MAX TAKE-OFF for any throttle position. The alpha floor function can only be overridden by pilot's action on the ATS disconnect switches located on the throttle control levers.
3 Memo Thrust Setting
_ When ATHR is deactivated, the thrust can be frozen to the actual value (see para Thrust Setting); in this case the thrust is set accordingly to a logic shown on the referenced illustrations.
E. Engine Starting/Ignition Control R (Ref. Fig. 020)
(1) General There are two modes of starting control associated with two different procedures and corresponding to two engine starting logics in the ECU
(a) Automatic starting logic under the full authority of the FADEC system. The FADEC initiates the automatic sequence of command to:
- starter air valve opening and closing
- HP fuel valve
- ignition exciters
The FADEC provides:
- engine limits protection N1, N2, EGT
- on ground start abort in case of detected incident (hot start, stall, failure to light, hung start, starter time exceedance)
- in flight start, only fault announcement, without automatic start abort
- specific fault message transmission.
(b) Alternate starting logic with authority of the FADEC limited to :
- actuation of starter air valve upon manual cockpit actions on MAN START pushbutton switch and by selection on IGN/START position of the selector switch on ENG panel
- ignition exciter energization and HP fuel shut off valve upon manual setting of ENG MASTER switch to ON
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Engine Panels Figure 020
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- cancellation of ignition and starter air valve is automatically done by the FADEC
- warning indications are also provided
- passive survey of engine is provided during start without authority to abort it, exception case of EGT overlimit below 50 percent N2 on ground (start abort). Other FADEC functions are associated to the starting function such as engine cranking, flame out detection and continuous ignition selection.
(2) Automatic Start
(a) Engine starting logic The FADEC has the capability to perform starting of the engine, including protection of the engine during the starting phase with the necessary indication to the cockpit. The FADEC operates with the following sequence :
- the selector being to ignition position, the FADEC opens the starter air valve when the ENG MASTER switch is switched to ON
- when N2 reaches 16 percent rpm the FADEC switches the exciter ON
- at N2 = 22 percent rpm the FADEC open the fuel shut off valve
- at N2 = 50 percent rpm the FADEC closes the starter air valve and deenergizes the ignition exciter
- then the FADEC controls the fuel according to the start fuel schedule
- in case of ignition delay, the FADEC will automatically operate both ignition exciters after an automatic dry motoring sequence and will provide information to DMC
- for airstart FADEC identifies windmilling or starter assist conditions 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：A320飞机维护手册 AMM 发动机燃油和控制 ENGINE FUEL AND CONTRO(88)
