ELECTRONIC ENGINE CONTROL
77. As stated in para. 8, some engines utilize a system of electronic control to monitor engine performance and make necessary control inputs to maintain certain engine parameters within predeter-mined limits. The main areas of control are engine shaft speeds and exhaust gas temperature (E.G.T.) which are continuously monitored during engine operation. Some types of electronic control function as a limiter only, that is, should engine shaft speed or
E.G.T.
approach the limits of safe operation, then an input is made to the fuel flow regulator (F.F.R.) to reduce the fuel flow thus maintaining shaft speed or
E.G.T.
at a safe level. Supervisory control systems may contain a limiter function but, basically, by using aircraft generated data, the system enables a more appropriate thrust setting to be selected quickly and
75.隨著油門關閉，慢車狀態由控制經慢車調節器和地面慢車電磁閥進行通風的空氣量來確定。在工作中通過此二者同時放氣，保證了在發動機有空氣提取時仍有滿意的空中慢車。通過關閉電磁閥可獲得地面慢車時的低功率狀態。
74．高壓軸轉速也由此輔助節流活門調節。萬一其他控制裝置失靈，而且油泵轉速增加時，燃油壓力將此節流活門關閉，并打開壓力降溢流活門，從而減小燃油流量。
73．為了防止超過低壓壓氣機的最大轉速和發動機燃氣溫度。在燃油泵出口處裝了一個活門，即輔助節流活門。在穩態運轉狀態下，該活門在彈簧力作用下保持打開。當到達極限狀態時，燃油流量依據發動機的轉速和溫度信號而減少。信號被放大，并傳至旋轉作動筒，來減小可調限流器的面積。這個動作的效果是增大燃油壓力，此壓力又部分地關小節流活門。作用在壓力降溢流活門表面上的高壓燃油的壓力增加，溢流活門打開，因而減步向噴嘴供應的燃油流量。
個輸入量，使燃油流量減步，將軸轉速或排氣溫度保持在安全水平上。監督控制系統可以具有限制器的功能，但是基本上它利用飛機提供的數據保證駕駛員能夠快速而又精確地選擇更為適當的推力位置。然后，控制系統進行微調，保持發動機的推力符合駕駛員預先設定的值，而不管大氣條件如何變化。全權限數字式發動機控制器(F.A.D.E.C.)實際上接管了所有的穩態和瞬態的控制智能，并取代了燃油系統中絕大多數的液壓機械和氣動元件。因此，燃油系統簡化到一個油泵、一個控制活門、一個單獨的停車開關，以及在大量電子損壞的情況下必須要用來保證發動機安全的步量的附加裝置。
78．全權限燃油控制器(F.A.F.C.)以與全權數字式發動機控制器相同的方式對發動機的燃油系統進行全電子式控制，但是它沒有用來控制壓氣機空氣流量系統的瞬態控制智能能力，而現在正用的發動機控制系統卻具有這種能力。
76．與組合式加速和轉速控制系統相似，這一燃油系統也沒有采用增壓活門來將燃油從油泵分配到主油路及初級油路。
發動機電子控制
77．如第8段所述，某些發動機采用電子控制系統來監視發動機的性能并提供必要的控制輸入量，將一些發動機參數保持在預定的極限值之內�？刂频闹饕I域是發動機軸轉速及排氣溫度，這些都是在發動機工作中要連續監視的。有些類型的電子控制器僅僅起一個限制器功用。即一旦發動機軸轉速或排氣溫度接近安全工作極限，那么就會向燃油流量調節器提供一
accurately by the pilot. The control system then makes small control adjustments to maintain engine thrust consistent with that pre-set by the pilot, regardless of changing atmospheric conditions. Full authority digital engine control (FAD.E.G.) takes over virtually all of the steady state and transient control intelligence and replaces most of the hydromechani-cal and pneumatic elements of the fuel system. The fuel system is thus reduced to a pump and control valve, an independent shut-off cock and a minimum of additional features necessary to keep the engine safe in the event of extensive electronic failure.
78. Full authority fuel control (F.A.F.C.) provides full electronic control of the engine fuel system in the same way as F.A.D.E.C., but has none of the transient control intelligence capability used to control the compressor airflow system as the existing engine control system is used for these.
Speed and temperature control amplifiers
79. The speed and temperature control amplifier receives signals from thermocouples measuring
E.G.T. and from speed probes sensing L.P. and in some cases, L.P. shaft speeds (N1 and N2). The amplifier basically comprises speed and temperature channels which monitor the signals sensed. If either N1, N2 or E.G.T. exceed pre-set datums, the amplifier output stage is triggered to connect an electrical supply to a solenoid valve (para. 47) or a variable restrictor (para. 73) which override the F.F.R. and cause a reduction in fuel flow. The limiter will only relinquish control back to the F.F.R. if the input conditions are altered (altitude, speed, ambient temperature or throttle lever position). The limiter system is designed to protect against parameters exceeding their design values under normal operation and basic fuel system failures.
Engine supervisory control
80. The engine supervisory control (E.S.C.) system performs a supervisory function by trimming the fuel flow scheduled by the fuel flow governor (F.F.G.) to match the actual engine power with a calculated engine power for a given throttle angle. The E.S.C. provides supervisory and limiting functions by means of a single control output signal to a torque motor in the F.F.G. In order to perform its supervisory function the E.S.C. monitors inputs of throttle angle, engine bleed state, engine pressure ratio (E.P.R.) and air data computer information (altitude, Mach number and temperatures). From this data the supervisory channel predicts the value of N1 required to achieve the command E.P.R. calculated for the throttle angle set by the pilot. Simultaneously a comparison is made between the command E.P.R. and the actual
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