ECE Regulation ECE准则eddy-current type 电涡流式efe heater
进气加热器Effective height 有效中度Effective Weighted factor
有效加权周到Effective width 有效宽度Electrical 小车电器Electrical System
电器系electromagnetic compatibility 电磁包容性EMBOSSMENT 凸字Emergency
Brake 迫切制动器Emergency Exit 火急出口Emergency Motor Vehicles
应急用车Emergency Signals 应急时域信号用具Emergency Stop Indication Devices
迫切停车表示用具emergency valve 应急阀Emission Control Device
排泄物资调剂节装置end clearance 轴向间隙ENFORCEMENT PROCEDURE
施行规程Enforcement Regulation 施行法规engine 斯特林发动机，引擎Engine and
Power Train System 内燃机及引力传动系engine assy. 内燃机总成engine
displacement 外燃机排放量engine hood 汽油发动机罩engine intake manifold
内燃机进气歧管engine load 内燃机负荷engine oil 斯特林发动机润滑油engine oil
capacity 发动机机械油体积engine outside diagram 外燃机外形图engine
revolution speed 内燃机转速engine type 外燃机型号Engineering and Safety
Department 技能安全体entrance step 入口台阶entry item 填写项目entry
value 填入值eqalizer 平衡架Equivalent inertia weight 当量惯性重量escort
vehicle 护卫车European Economic Community Command
欧共体指令Examination 审核examination affair 考察事务Exception
to application 不适用条目款项excrement 排放物exhaust 排水管exhaust duration
排气持续角exhaust emission 排气排放物Exhaust Emission Control Device
排泄物资调剂整装置exhaust hose 排放管exhaust manifold 排气歧管exhaust sytem
排气系统exhaust tube 放气管exhaust valve 排气门exhaust valve timing
排气门定时expander oil rail 油环衬簧expansion box 膨胀盒expansion core
蒸发器芯expansion valve body 阀体extension case 外接壳体EXTE凯雷德NAL
PROJECTION 外部出色物External 平板电脑 外表面External view 外观图extreme
idle screw 极限怠速调解螺钉factory plate model 厂牌型号fan 电风扇fan belt
电风扇皮带fan & viscous drive 风扇及硅油干式电磁离合器fast idle cam 快怠速凸轮fast
idle cam link 快怠速凸轮连杆fast idle cam second step
快怠速凸轮第二阶段fast idle cam setting index 快怠速凸轮调解刻度fast
idle mode 快怠速状态fast idle screw 快怠速调治螺钉fast idle speed
快怠速转速Federal Motor Vehicles Safety Standards
美利坚联邦合众国际联盟邦机动车安全标准Feeling test 认为试验Fiducial marks
基准标识Filament Lamp 白炽灯filler neck seal 加格陵兰挪威长臂鳕密闭filler opening
进油口Filling-in Procedure 填写规程Filling-in Procedure for Each Item
种种型的填写规程filter 滤清器，滤网Filter characteristics
滤Porter性Filtering 滤波Fire Extinguisher 灭火器Fire truck 消防车fitting,
flow control valve 流量调控阀接头fix shaft 定位轴flange 法兰flash point
闪点flasher, hazard lamp 惊险报告警察方闪光器Flexible Disk 软盘float 浮子float
level 浮筒油面中度float pin 浮子轴floating coat 中涂floor damper
地板加速踏板flow control valve 流量调整阀Fluid container 液体容器fluid
torque converter 液力变扭器fluorescent 华为平板 荧光面flying wheel
飞轮fog lamp 雾灯fog lamp relay 雾灯继电器fog lamp switch 雾灯按钮Foil
Thickness 箔厚folded seat 折叠椅folding seat 折叠式座椅foot angle
quadrant 小腿夹角量角器fork 拨叉Formalin 福尔马林forward-opening inner
door 内门前开型four-stroke cycle 四里程引擎four-wheel drive motor
vehicle 四轮驱动的机火车Four-wheeled 四轮Frame 车架Frame and Body
车架及车身Friction clutch 摩擦磁粉离合器from evaporator drier 自蒸发器from
heater core 出加热器from receiver drier 自贮液干燥器from water jacket
intake manifold 自进气歧管水套front axle 前桥front axle assy.
前桥总成front axle motor 前桥挂档马达front bearing 前轴承front bearing
retainer 前轴承盖front bearing, front output shaft 前输出轴前轴承front
bearing, input shaft 输入轴前轴承front bearing, output shaft
输出轴前轴承front brake disc 前制动盘front brake disc assy.
前制动盘总成front case 前壳体front case of vacuum booster
助力器前壳体front coil spring 前螺旋弹簧front combined lamps
前组合灯front disk braker 前盘式制动器front edge 前面缘front end of
shield 发电机前端盖front engine front drive F.F.式车辆front engine
rear drive F.奥迪Q5.式车辆front fan 前电扇Front Fog Lamp 前雾灯front
front axle 前前桥front opening 出油口front output shaft 前输出轴front
output shaft gear 前输出轴齿轮Front overhang 前悬front panel 前板front
pinion bearing 前主动齿轮轴承front port 前接口front propeller shaft
前传动轴front propeller shaft assy. 前传动轴总成front shock absorber
前减震器front stabilizer 前稳高杆front suspension 前悬吊front thrust
plate 前配流盘front transfer 车辆转移台front tube failure
前管路失效状态front wall angle cover 前围角板front washer pump
前冲洗器泵front washer reservoir 前风挡洗刷器储液罐front wheel
前轮，前壳体front wheel alignment 前轮定位front wheel brake
前轮制动器Front Windshield 前风窗front wiper motor
前刮水器内燃机Front-End Outline 马克尔 Lamps 前端示廓灯Fuel 燃料fuel
direct 燃油走向fuel filter 集滤器fuel filter housing 燃油滤清器壳体fuel
filter paper 燃油滤清器滤纸fuel gauge 燃油表fuel gauge calibration
燃油表电阻Fuel Injection Device 燃料喷射装置fuel level indicator
机油压力表fuel pump 然油泵Fuel Resistance 耐油性fuel sensor
燃油传感器fuel sensor harness 燃油传感器线束fuel supply system
供油系Fuel System 燃料系Fuel System of Motor Vehicles Whose Fuel Is
High-Pressure Gas 以高压气体作为燃料的机火车燃料系Fuel System of Motor
Vehicles Whose Fuel Is Producer Gas
以爆发炉煤气作为燃料的机轻轨燃料系Fuel Tank 燃料箱fule metering bar
计量杆full circle 大循环Full flow dilution 全流稀释full trailer
全挂车full-hydraulic type 全液力式full-trailer 全挂车fully-loaded
全负荷fuse 熔断器fuse panel 熔断器板
- B – C – D – E – F – G – H – I – J – K – L – M – N – O – P – Q – R – S
- T – U – V – WEE-ring – Е-образная стопорная шайбаeach – каждый,
всякийear – ухо, ушко, проушинаearly type – старый типearth – земля,
заземлениеearth strap – кабель заземления / массыeasy – удобный, лёгкий,
пологийeccentric – эксцентрикeccentricity – эксцентриситетeconomic(al) –
хозяйственный, экономическийeconomizer jet – жиклёр экономайзераECU –
electronic control unit – электронный блок управленияeddy current –
вихревой ток, ток Фукоedge – край, кромка, лезвие, ребро, бортedition –
издание, тиражeffective – эффективный, полезныйefficiency – мощность,
отдача, КПДeffort – усилие, попытка, трудозатратыEFI – electronic fuel
injection – впрыск топлива под электронным управлениемEGR – exhaust gas
recirculation – рециркуляция выхлопных газовejector – эжектор,
выбрасыватель, выталкивательelastic – упругий, эластичный,
пружинящийelbow – колено, изгиб трубы, угольникelectric(al) –
электрический, электро-electric(al) equipment – электрическое
оборудованиеelectricity – электричество, эл. токelectrode – электрод,
вывод, клеммаelectrolyte – электролитelectromagnetic –
электромагнитныйelectromotive force – EMF – электродвижущая сила,
ЭДСelectron – электронelectron beam welding – электронно-лучевая
сваркаelectronic – электронныйelectropneumatic –
электро-пневматическийelement – элемент, часть, электрод
аккумулятораelliptic(al) – эллиптическийelongate – удлиняться,
растягиватьсяelongated – эллипсообразный, продолговатыйembedded –
вдавленный, заделанный, погружённый, утопленныйemblem – эмблема,
опознавательный знак, логоemerge – возникнуть, выясняться,
возникатьemergency – авария, критический случай, запасной,
аварийныйemergency valve – аварийный клапанemery cloth – шлифовальная /
наждачная шкурка на тканевой основеemery paper – наждачная бумагаemery
paste – шлифовальная пастаEMF – electromotive force – электродвижущая
сила, ЭДСemission – излучение, эмиссия, выброс, выделениеemission
control – предотвращение загрязненияemission control device – устройство
против загрязнения атмосферыemission control system – система по борьбе
с загрязнением атмосферыemitter – эмиттерempty – пустой, без нагрузки,
холостойemulsion tube – эмульсионная трубка карбюратораend – конец,
торец, край, головка шатунаend float – осевая игра, осевой зазорend gap
- зазор между концами / осямиend nipple – конец тросаend play –
продольное смещение, осевая игра, осевой зазорendothermic –
эндотермическийenergise, energize – подавать питание, включать
напряжение, возбуждатьenergiser, energizer – аккумулятор,
генераторenergy – энергияenergy absorbing bumper – буфер, поглощающий
энергию удараenergy absorbing steering column – колонка рулевого
управления с поглощением энергииengage – зацеплять, включать, вводить в
зацепление, соединятьengaging – зацепляющий, включающийengine –
двигатель, моторengine block – блок цилиндровengine braking – торможение
двигателемengine compartment – моторное отделениеengine overhaul –
капремонт / переборка двигателяengine room – моторное отделениеenlarge –
увеличиватьenrich – обогащатьenricher – обогатительenrichment circuit –
схема обогащенияentry – вход, место входаenvelope – чехол, оболочка,
покрытие, колба эл.лампыepicyclic gear – планетарая / эпициклическая
передачаequal – одинаковый, равныйequaliser, equalizer – балансир,
уравнитель, коромыслоequilibrium – равновесиеequip – снаряжать,
оборудовать, оснащатьequipment – оборудование, оснащение,
снаряжениеerase – стирание из памятиerosion – коррозия, ржавление, износ
лакокрасочного покрытияerratic – неправильный, разбросанный,
дефектныйerror – ошибка, погрешностьescutcheon – щиток с надписью,
паспорт, маркаestablish – основывать, устанавливатьestate car –
автомобиль с кузовом типа “универсал” / “фургон”evacuate – выкачивать,
создавать вакуум, разрежатьevaporate – испарятьсяevaporation –
испарение, парообразованиеevaporative canister – резервуар с
активированным углём для абсорбции паров бензинаevaporative emission
control system – система, препятствующая испарению топливаevaporator –
испаритель, выпарной аппаратeven – ровный, гладкий,
сглаживатьeverlasting – прочный, выносливыйevery – каждыйexamination –
осмотр, исследование, экспертизаexample – примерexcept – кроме, за
исключениемexcess(ive) – больше нормы, чрезмерный, избыточныйexecute –
выполнить, ввести в действиеexecution – выполнение, исполнениеexhaust –
выпуск, выхлоп, выпускать, разрежать воздухexhaust emission control
system – система по борьбе с загрязнением атмосферыexhaust gas –
выхлопные газыexhaust gas analyser – анализатор отработавших / выхлопных
газовEGR – exhaust gas recirculation – рециркуляция отработанных
газовexhaust gas sensor – датчик содержания кислорода в выхлопных
газахexhaust manifold – выпускная труба, выпускной коллекторexhaust pipe
- выхлопная трубаexhaust port – выхлопное отверстие, выпускное окно,
выпускной каналexhaust stroke – такт / ход выпускаexhaust system – такт
/ выпускная системаexhauster – вытяжной вентилятор, эксгаустерexit –
выезд, съезд (с магистрали)expand – расширяться, увеличиваться в объёме,
развальцовыватьexpander – расширитель, приспособление для расширения /
растягиванияexpansion – расширение, растягивание, развальцовка,
понижение давленияexpansion stroke – такт / ход расширения, рабочий
ходexpansion tank – расширительный бачокexplode – взорваться,
взрыватьexploded view – изображение механизма в разобранном
видеexplosion – взрыв, вспышка, внутреннее сгораниеexport –
экспортexposed – видимый, открытыйextend – расширять, увеличивать,
вытягивать, простиратьсяextension – растяжение вытягивание,
удлинениеextent – протяжённость, степень, мераexterior – внешний,
наружныйexternal – внешний, наружныйextinguisher – огнетушительextra –
дополнительный, добавочный, исключительноextract – извлекать,
удалятьextractor – клещи, вытаскиватель, съёмникextreme – крайняя
степень, чрезвычайныйextreme pressure oil – масло,выдерживающее высокое
давлениеextremely – чрезвычайно, крайнеeye – глазок, ушко,
проушинаeyebolt – винт / болт с ушкомeyelet – проушина, монтажная петля
на конце провода, кольцо для крепления
A supercharger is an engine-driven air pump or compressor that increases
manifold pressure and forces the fuel/air mixture into the cylinders.
The higher the manifold pressure, the more dense the fuel/air mixture,
and the more power an engine can produce. With a normally aspirated
engine, it is not possible to have manifold pressure higher than the
existing atmospheric pressure. A supercharger is capable of boosting
manifold pressure above 30 in. Hg.
The components in a supercharged induction system are similar to those
in a normally aspirated system, with the addition of a supercharger
between the fuel metering device and intake manifold. A supercharger is
driven by the engine through a gear train at one speed, two speeds, or
variable speeds. In addition, superchargers can have one or more stages.
Each stage provides an increase in pressure. Therefore, superchargers
may be classified as single stage, two stage, or multistage, depending
on the number of times compression occurs.
An early version of a single-stage, single-speed supercharger may be
referred to as a sea-level supercharger. An engine equipped with this
type of supercharger is called a sea-level engine. With this type of
supercharger, a single gear-driven impeller is used to increase the
power produced by an engine at all altitudes. The drawback, however, is
that with this type of supercharger, engine power output still decreases
with an increase in altitude, in the same way that it does with a
normally aspirated engine.
Single-stage, single-speed superchargers are found on many high-powered
radial engines, and use an air intake that faces forward so the
induction system can take full advantage of the ram air. Intake air
passes through ducts to a carburetor, where fuel is metered in
proportion to the airflow. The fuel/air charge is then ducted to the
supercharger, or blower impeller, which accelerates the fuel/air mixture
outward. Once accelerated, the fuel/air mixture passes through a
diffuser, where air velocity is traded for pressure energy. After
compression, the resulting high pressure fuel/air mixture is directed to
Some of the large radial engines developed during World War II have a
single-stage, two-speed supercharger. With this type of supercharger, a
single impeller may be operated at two speeds. The low impeller speed is
often referred to as the low blower setting, while the high impeller
speed is called the high blower setting. On engines equipped with a
two-speed supercharger, a lever or switch in the cockpit activates an
oil-operated clutch that switches from one speed to the other.
Under normal operations, takeoff is made with the supercharger in the
low blower position. In this mode, the engine performs as a
ground-boosted engine, and the power output decreases as the aircraft
gains altitude. However, once the aircraft reaches a specified altitude,
a power reduction is made, and the supercharger control is switched to
the high blower position. The throttle is then reset to the desired
manifold pressure. An engine equipped with this type of supercharger is
called an altitude engine.
Figure 11: Power output of normally aspirated engine compared to a
single-stage, two-speed supercharged engine.
The most efficient method of increasing horsepower in a reciprocating
engine is by use of a turbosupercharger, or turbocharger, as it is
usually called. A drawback of gear-driven superchargers is that they use
a large amount of the engine´s power output for the amount of power
increase they produce. This problem is avoided with a turbocharger,
because turbochargers are powered by an engine´s exhaust gases. This
means a turbocharger recovers energy from hot exhaust gases that would
otherwise be lost.
Another advantage of turbochargers is that they can be controlled to
maintain an engine´s rated sea-level horsepower from sea level up to the
engine´s critical altitude. Critical altitude is the maximum altitude at
which a turbocharged engine can produce its rated horsepower. Above the
critical altitude, power output begins to decrease like it does for a
normally aspirated engine.
Turbochargers increase the pressure of the engine´s induction air, which
allows the engine to develop sea level or greater horsepower at higher
altitudes. A turbocharger is comprised of two main elements—a turbine
and a compressor. The compressor section houses an impeller that turns
at a high rate of speed. As induction air is drawn across the impeller
blades, the impeller accelerates the air, allowing a large volume of air
to be drawn into the compressor housing. The impeller´s action
subsequently produces high-pressure, high-density air, which is
delivered to the engine. To turn the impeller, the engine´s exhaust
gases are used to drive a turbine wheel that is mounted on the opposite
end of the impeller´s drive shaft. By directing different amounts of
exhaust gases to flow over the turbine, more energy can be extracted,
causing the impeller to deliver more compressed air to the engine. The
waste gate is used to vary the mass of exhaust gas flowing into the
turbine. A waste gate is essentially an adjustable butterfly valve that
is installed in the exhaust system. When closed, most of the exhaust
gases from the engine are forced to flow through the turbine. When open,
the exhaust gases are allowed to bypass the turbine by flowing directly
out through the engine´s exhaust pipe.
Figure 12: Turbocharger components.
Since the temperature of a gas rises when it is compressed,
turbocharging causes the temperature of the induction air to increase.
To reduce this temperature and lower the risk of detonation, many
turbocharged engines use an intercooler. An intercooler is a small heat
exchanger that uses outside air to cool the hot compressed air before it
enters the fuel metering device.
On most modern turbocharged engines, the position of the waste gate is
governed by a pressure-sensing control mechanism coupled to an actuator.
Engine oil directed into or away from this actuator moves the waste gate
position. On these systems, the actuator is automatically positioned to
produce the desired MAP simply by changing the position of the throttle
Other turbocharging system designs use a separate manual control to
position the waste gate. With manual control, you must closely monitor
the manifold pressure gauge to determine when the desired MAP has been
achieved. Manual systems are often found on aircraft that have been
modified with aftermarket turbocharging systems. These systems require
special operating considerations. For example, if the waste gate is left
closed after descending from a high altitude, it is possible to produce
a manifold pressure that exceeds the engine´s limitations. This
condition is referred to as an overboost, and it may produce severe
detonation because of the leaning effect resulting from increased air
density during descent.
Although an automatic waste gate system is less likely to experience an
overboost condition, it can still occur.
If you try to apply takeoff power while the engine oil temperature is
below its normal operating range, the cold oil may not flow out of the
waste gate actuator quickly enough to prevent an overboost. To help
prevent overboosting, you should advance the throttle cautiously to
prevent exceeding the maximum manifold pressure limits.
There are system limitations that you should be aware of when flying an
aircraft with a turbocharger. For instance, a turbocharger turbine and
impeller can operate at rotational speeds in excess of 80,000 r.p.m.
while at extremely high temperatures. To achieve high rotational speed,
the bearings within the system must be constantly supplied with engine
oil to reduce the frictional forces and high temperature. To obtain
adequate lubrication, the oil temperature should be in the normal
operating range before high throttle settings are applied. In addition,
you should allow the turbocharger to cool and the turbine to slow down
before shutting the engine down. Otherwise, the oil remaining in the
bearing housing will boil, causing hard carbon deposits to form on the
bearings and shaft.
These deposits rapidly deteriorate the turbocharger´s efficiency and
service life. For further limitations, refer to the AFM/POH.
High altitude performance
As an aircraft equipped with a turbocharging system climbs, the waste
gate is gradually closed to maintain the maximum allowable manifold
pressure. At some point, however, the waste gate will be fully closed,
and with further increases in altitude, the manifold pressure will begin
to decrease. This is the critical altitude, which is established by the
airplane or engine manufacturer. When evaluating the performance of the
turbocharging system, if the manifold pressure begins decreasing before
the specified critical altitude, the engine and turbocharging system
should be inspected by a qualified aviation maintenance technician to
verify the system´s proper operation.
Excursion: Turbine engines
The ignition system provides the spark that ignites the fuel/air mixture
in the cylinders and is made up of magnetos, spark plugs, high-tension
leads, and the ignition switch.
Figure 13: Ignition system components.
A magneto uses a permanent magnet to generate an electrical current
completely independent of the aircraft´s electrical system. The magneto
generates sufficiently high voltage to jump a spark across the spark
plug gap in each cylinder. The system begins to fire when you engage the
starter and the crankshaft begins to turn. It continues to operate
whenever the crankshaft is rotating.
Most standard certificated airplanes incorporate a dual ignition system
with two individual magnetos, separate sets of wires, and spark plugs to
increase reliability of the ignition system. Each magneto operates
independently to fire one of the two spark plugs in each cylinder. The
firing of two spark plugs improves combustion of the fuel/air mixture
and results in a slightly higher power output. If one of the magnetos
fails, the other is unaffected. The engine will continue to operate
normally, although you can expect a slight decrease in engine power. The
same is true if one of the two spark plugs in a cylinder fails.
The operation of the magneto is controlled in the cockpit by the
ignition switch. The switch has five positions:
With RIGHT or LEFT selected, only the associated magneto is activated.
The system operates on both magnetos with BOTH selected.
You can identify a malfunctioning ignition system during the pretakeoff
check by observing the decrease in r.p.m. that occurs when you first
move the ignition switch from BOTH to RIGHT, and then from BOTH to LEFT.
A small decrease in engine r.p.m. is normal during this check. The
permissible decrease is listed in the AFM or POH. If the engine stops
running when you switch to one magneto or if the r.p.m. drop exceeds the
allowable limit, do not fly the airplane until the problem is corrected.
The cause could be fouled plugs, broken or shorted wires between the
magneto and the plugs, or improperly timed firing of the plugs. It
should be noted that “no drop” in r.p.m. is not normal, and in that
instance, the airplane should not be flown.
Following engine shutdown, turn the ignition switch to the OFF position.
Even with the battery and master switches OFF, the engine can fire and
turn over if you leave the ignition switch ON and the propeller is moved
because the magneto requires no outside source of electrical power. The
potential for serious injury in this situation is obvious.
Loose or broken wires in the ignition system also can cause problems.
For example, if the ignition switch is OFF, the magneto may continue to
fire if the ignition switch ground wire is disconnected. If this occurs,
the only way to stop the engine is to move the mixture lever to the idle
cutoff position, then have the system checked by a qualified aviation
During normal combustion, the fuel/air mixture burns in a very
controlled and predictable manner. Although the process occurs in a
fraction of a second, the mixture actually begins to burn at the point
where it is ignited by the spark plugs, then burns away from the plugs
until it is all consumed. This type of combustion causes a smooth
buildup of temperature and pressure and ensures that the expanding gases
deliver the maximum force to the piston at exactly the right time in the
Figure 14: Normal combustion and explosive combustion.
Detonation is an uncontrolled, explosive ignition of the fuel/air
mixture within the cylinder´s combustion chamber. It causes excessive
temperatures and pressures which, if not corrected, can quickly lead to
failure of the piston, cylinder, or valves. In less severe cases,
detonation causes engine overheating, roughness, or loss of power.
Detonation is characterized by high cylinder head temperatures, and is
most likely to occur when operating at high power settings. Some common
operational causes of detonation include:
Using a lower fuel grade than that specified by the aircraft
Operating with extremely high manifold pressures in conjunction with low
Operating the engine at high power settings with an excessively lean
Detonation also can be caused by extended ground operations, or steep
climbs where cylinder cooling is reduced.
Detonation may be avoided by following these basic guidelines during the
various phases of ground and flight operations:
Make sure the proper grade of fuel is being used.
While on the ground, keep the cowl flaps (if available) in the full-open
position to provide the maximum airflow through the cowling.
During takeoff and initial climb, the onset of detonation can be reduced
by using an enriched fuel mixture, as well as using a shallower climb
angle to increase cylinder cooling.
Avoid extended, high power, steep climbs.
Develop a habit of monitoring the engine instruments to verify proper
operation according to procedures established by the manufacturer.
Preignition occurs when the fuel/air mixture ignites prior to the
engine´s normal ignition event. Premature burning is usually caused by a
residual hot spot in the combustion chamber, often created by a small
carbon deposit on a spark plug, a cracked spark plug insulator, or other
damage in the cylinder that causes a part to heat sufficiently to ignite
the fuel/air charge.
Preignition causes the engine to lose power, and produces high operating
temperature. As with detonation, preignition may also cause severe
engine damage, because the expanding gases exert excessive pressure on
the piston while still on its compression stroke.
Detonation and preignition often occur simultaneously and one may cause
the other. Since either condition causes high engine temperature
accompanied by a decrease in engine performance, it is often difficult
to distinguish between the two. Using the recommended grade of fuel and
operating the engine within its proper temperature, pressure, and r.p.m.
ranges reduce the chance of detonation or preignition.
The fuel system is designed to provide an uninterrupted flow of clean
fuel from the fuel tanks to the engine. The fuel must be available to
the engine under all conditions of engine power, altitude, attitude, and
during all approved flight maneuvers. Two common classifications apply
to fuel systems in small airplanes – gravity-feed and fuel-pump systems.
The gravity-feed system utilizes the force of gravity to transfer the
fuel from the tanks to the engine – for example, on high-wing airplanes
where the fuel tanks are installed in the wings. This places the fuel
tanks above the carburetor, and the fuel is gravity fed through the
system and into the carburetor. If the design of the airplane is such
that gravity cannot be used to transfer fuel, fuel pumps are installed –
for example, on low-wing airplanes where the fuel tanks in the wings are
located below the carburetor.
Figure 15: Gravity-feed and fuel-pump systems.
Airplanes with fuel pump systems have two fuel pumps. The main pump
system is engine driven, and an electrically driven auxiliary pump is
provided for use in engine starting and in the event the engine pump
fails. The auxiliary pump, also known as a boost pump, provides added
reliability to the fuel system. The electrically driven auxiliary pump
is controlled by a switch in the cockpit.
Both gravity fed and pump systems may incorporate a fuel primer into the
system. The primer is used to draw fuel from the tanks to vaporize it
directly into the cylinders prior to starting the engine. This is
particularly helpful during cold weather, when engines are hard to start
because there is not enough heat available to vaporize the fuel in the
carburetor. It is important to lock the primer in place when it is not
in use. If the knob is free to move, it may vibrate out during flight
and can cause an excessively rich mixture. To avoid overpriming, read
the priming instructions for your airplane.
The fuel tanks, normally located inside the wings of an airplane, have a
filler opening on top of the wing through which they can be filled. A
filler cap covers this opening. The tanks are vented to the outside to
maintain atmospheric pressure inside the tank. They may be vented
through the filler cap or through a tube extending through the surface
of the wing. Fuel tanks also include an overflow drain that may stand
alone or be collocated with the fuel tank vent. This allows fuel to
expand with increases in temperature without damage to the tank itself.
If the tanks have been filled on a hot day, it is not unusual to see
fuel coming from the overflow drain.
The fuel quantity gauges indicate the amount of fuel measured by a
sensing unit in each fuel tank and is displayed in gallons or pounds.
Aircraft certification rules only require accuracy in fuel gauges when
they read “empty.” Any reading other than “empty” should be verified. Do
not depend solely on the accuracy of the fuel quantity gauges. Always
visually check the fuel level in each tank during the preflight
inspection, and then compare it with the corresponding fuel quantity
If a fuel pump is installed in the fuel system, a fuel pressure gauge is
also included. This gauge indicates the pressure in the fuel lines. The
normal operating pressure can be found in the AFM/POH, or on the gauge
by color coding.
The fuel selector valve allows selection of fuel from various tanks. A
common type of selector valve contains four positions: LEFT, RIGHT,
BOTH, and OFF. Selecting the LEFT or RIGHT position allows fuel to feed
only from that tank, while selecting the BOTH position feeds fuel from
both tanks. The LEFT or RIGHT position may be used to balance the amount
of fuel remaining in each wing tank.
Figure 16: Fuel selector valve.
Fuel placards will show any limitations on fuel tank usage, such as
“level flight only” and/or “both” for landings and takeoffs.
Regardless of the type of fuel selector in use, fuel consumption should
be monitored closely to ensure that a tank does not run completely out
of fuel. Running a fuel tank dry will not only cause the engine to stop,
but running for prolonged periods on one tank causes an unbalanced fuel
load between tanks. Running a tank completely dry may allow air to enter
the fuel system, which may cause vapor lock. When this situation
develops, it may be difficult to restart the engine. On fuel-injected
engines, the fuel may become so hot it vaporizes in the fuel line, not
allowing fuel to reach the cylinders.
Fuel strainers, sumps, and drains
After the fuel selector valve, the fuel passes through a strainer before
it enters the carburetor. This strainer removes moisture and other
sediments that might be in the system. Since these contaminants are
heavier than aviation fuel, they settle in a sump at the bottom of the
strainer assembly. A sump is defined as a low point in a fuel system
and/or fuel tank. The fuel system may contain sump, fuel strainer, and
fuel tank drains, some of which may be collocated.
The fuel strainer should be drained before each flight.
Fuel samples should be drained and checked visually for water and
contaminants. Water in the sump is hazardous because in cold weather the
water can freeze and block fuel lines. In warm weather, it can flow into
the carburetor and stop the engine. If water is present in the sump, it
is likely there is more water in the fuel tanks, and you should continue
to drain them until there is no evidence of water. In any event, never
take off until you are certain that all water and contaminants have been
removed from the engine fuel system.
Because of the variation in fuel systems, you should become thoroughly
familiar with the systems that apply to your airplane. Consult the AFM
or POH for specific operating procedures.
Aviation gasoline, or AVGAS, is identified by an octane or performance
number (grade), which designates the antiknock value or knock resistance
of the fuel mixture in the engine cylinder. The higher the grade of
gasoline, the more pressure the fuel can withstand without detonating.
Lower grades of fuel are used in lower-compression engines because these
fuels ignite at a lower temperature. Higher grades are used in
higher-compression engines, because they must ignite at higher
temperatures, but not prematurely. If the proper grade of fuel is not
available, use the next higher grade as a substitute. Never use a lower
grade. This can cause the cylinder head temperature and engine oil
temperature to exceed their normal operating range, which may result in
Several grades of aviation fuel are available. Care must be exercised to
ensure that the correct aviation grade is being used for the specific
type of engine. The proper fuel grade is stated in the AFM or POH, on
placards in the cockpit, and next to the filler caps. Due to its lead
content, auto gas should NEVER be used in aircraft engines unless the
aircraft has been modified with a Supplemental Type Certificate (STC)
issued by the Federal Aviation Administration.
The current method to identify aviation gasoline for aircraft with
reciprocating engines is by the octane and performance number, along
with the abbreviation AVGAS. These aircraft use AVGAS 80, 100, and
100LL. Although AVGAS 100LL performs the same as grade 100, the “LL”
indicates it has a low lead content.
Fuel for aircraft with turbine engines is classified as JET A, JET A-1,
and JET B. Jet fuel is basically kerosene and has a distinctive kerosene
Since use of the correct fuel is critical, dyes are added to help
identify the type and grade of fuel.
Figure 17: Aviation fuel color-coding system.
In addition to the color of the fuel itself, the color-coding system
extends to decals and various airport fuel handling equipment. For
example, all aviation gasolines are identified by name, using white
letters on a red background. In contrast, turbine fuels are identified
by white letters on a black background.
Of the accidents attributed to powerplant failure from fuel
contamination, most have been traced to:
Inadequate preflight inspection by the pilot.
Servicing aircraft with improperly filtered fuel from small tanks or
Storing aircraft with partially filled fuel tanks.
Lack of proper maintenance.
Fuel should be drained from the fuel strainer quick drain and from each
fuel tank sump into a transparent container, and then checked for dirt
and water. When the fuel strainer is being drained, water in the tank
may not appear until all the fuel has been drained from the lines
leading to the tank. This indicates that water remains in the tank, and
is not forcing the fuel out of the fuel lines leading to the fuel
strainer. Therefore, drain enough fuel from the fuel strainer to be
certain that fuel is being drained from the tank. The amount will depend
on the length of fuel line from the tank to the drain. If water or other
contaminants are found in the first sample, drain further samples until
no trace appears.
Water may also remain in the fuel tanks after the drainage from the fuel
strainer had ceased to show any trace of water. This residual water can
be removed only by draining the fuel tank sump drains.
Water is the principal fuel contaminant. Suspended water droplets in the
fuel can be identified by a cloudy appearance of the fuel or by the
clear separation of water from the colored fuel, which occurs after the
water has settled to the bottom of the tank. As a safety measure, the
fuel sumps should be drained before every flight during the preflight
Fuel tanks should be filled after each flight, or at least after the
last flight of the day to prevent moisture condensation within the tank.
Another way to prevent fuel contamination is to avoid refueling from
cans and drums. Refueling from cans or drums may result in fuel
The use of a funnel and chamois skin when refueling from cans or drums
is hazardous under any conditions, and should be discouraged. In remote
areas or in emergency situations, there may be no alternative to
refueling from sources with inadequate anticontamination systems, and a
chamois and funnel may be the only possible means of filtering fuel.
However, the use of a chamois will not always ensure decontaminated
Worn-out chamois will not filter water; neither will a new, clean
chamois that is already water-wet or damp.
Most imitation chamois skins will not filter water.
Static electricity is formed by the friction of air passing over the
surfaces of an airplane in flight and by the flow of fuel through the
hose and nozzle during refueling.
Nylon, dacron, or wool clothing is especially prone to accumulate and
discharge static electricity from the person to the funnel or nozzle. To
guard against the possibility of static electricity igniting fuel fumes,
a ground wire should be attached to the aircraft before the fuel cap is
removed from the tank. The refueling nozzle then should be grounded to
the aircraft before refueling is begun, and should remain grounded
throughout the refueling process. When a fuel truck is used, it should
be grounded prior to the fuel nozzle contacting the aircraft.
If fueling from drums or cans is necessary, proper bonding and grounding
connections are important.
Drums should be placed near grounding posts, and the following sequence
of connections observed:
Drum to ground.
Ground to aircraft.
Drum to aircraft.
Nozzle to aircraft before the fuel cap is removed.
When disconnecting, reverse the order.
The passage of fuel through a chamois increases the charge of static
electricity and the danger of sparks. The aircraft must be properly
grounded and the nozzle, chamois filter, and funnel bonded to the
aircraft. If a can is used, it should be connected to either the
grounding post or the funnel. Under no circumstances should a plastic
bucket or similar nonconductive container be used in this operation.
Most small aircraft use a direct-cranking electric starter system. This
system consists of a source of electricity, wiring, switches, and
solenoids to operate the starter and a starter motor. Most aircraft have
starters that automatically engage and disengage when operated, but some
older aircraft have starters that are mechanically engaged by a lever
actuated by the pilot.
The starter engages the aircraft flywheel, rotating the engine at a
speed that allows the engine to start and maintain operation.
Electrical power for starting is usually supplied by an on-board
battery, but can also be supplied by external power through an external
power receptacle. When the battery switch is turned on, electricity is
supplied to the main power bus through the battery solenoid. Both the
starter and the starter switch draw current from the main bus, but the
starter will not operate until the starting solenoid is energized by the
starter switch being turned to the “start” position. When the starter
switch is released from the “start” position, the solenoid removes power
from the starter motor. The starter motor is protected from being driven
by the engine through a clutch in the starter drive that allows the
engine to run faster than the starter motor.
Figure 18: Typical starting circuit.
When starting an engine, the rules of safety and courtesy should be
strictly observed. One of the most important is to make sure there is no
one near the propeller. In addition, the wheels should be chocked and
the brakes set, to avoid hazards caused by unintentional movement. To
avoid damage to the propeller and property, the airplane should be in an
area where the propeller will not stir up gravel or dust.
The engine oil system performs several important functions, including:
Lubrication of the engine´s moving parts.
Cooling of the engine by reducing friction.
Removing heat from the cylinders.
Providing a seal between the cylinder walls and pistons.
Carrying away contaminants.
Reciprocating engines use either a wet-sump or dry-sump oil system. In a
dry-sump system, the oil is contained in a separate tank, and circulated
through the engine by pumps. In a wet-sump system, the oil is located in
a sump, which is an integral part of the engine.
Figure 19: Wet-sump oil system.
The main component of a wet-sump system is the oil pump, which draws oil
from the sump and routes it to the engine. After the oil passes through
the engine, it returns to the sump. In some engines, additional
lubrication is supplied by the rotating crankshaft, which splashes oil
onto portions of the engine.
An oil pump also supplies oil pressure in a dry-sump system, but the
source of the oil is a separate oil tank, located external to the
engine. After oil is routed through the engine, it is pumped from the
various locations in the engine back to the oil tank by scavenge pumps.
Dry sump systems allow for a greater volume of oil to be supplied to the
engine, which makes them more suitable for very large reciprocating
The oil pressure gauge provides a direct indication of the oil system
operation. It measures the pressure in pounds per square inch (p.s.i.)
of the oil supplied to the engine. Green indicates the normal operating
range, while red indicates the minimum and maximum pressures. There
should be an indication of oil pressure during engine start. Refer to
the AFM/POH for manufacturer limitations.
The oil temperature gauge measures the temperature of oil. A green area
shows the normal operating range and the red line indicates the maximum
allowable temperature. Unlike oil pressure, changes in oil temperature
occur more slowly. This is particularly noticeable after starting a cold
engine, when it may take several minutes or longer for the gauge to show
any increase in oil temperature.
Check oil temperature periodically during flight especially when
operating in high or low ambient air temperature. High temperature
indications may indicate a plugged oil line, a low oil quantity, a
blocked oil cooler, or a defective temperature gauge. Low temperature
indications may indicate improper oil viscosity during cold weather
The oil filler cap and dipstick (for measuring the oil quantity) are
usually accessible through a panel in the engine cowling. If the
quantity does not meet the manufacturer´s recommended operating levels,
oil should be added. The AFM, POH, or placards near the access panel
provide information about the correct oil type and weight, as well as
the minimum and maximum oil quantity.
Figure 20: Always check the engine oil level during the preflight
Engine cooling systems
The burning fuel within the cylinders produces intense heat, most of
which is expelled through the exhaust system. Much of the remaining
heat, however, must be removed, or at least dissipated, to prevent the
engine from overheating. Otherwise, the extremely high engine
temperatures can lead to loss of power, excessive oil consumption,
detonation, and serious engine damage.
While the oil system is vital to internal cooling of the engine, an
additional method of cooling is necessary for the engine´s external
surface. Most small airplanes are air cooled, although some are liquid
Air cooling is accomplished by air flowing into the engine compartment
through openings in front of the engine cowling. Baffles route this air
over fins attached to the engine cylinders, and other parts of the
engine, where the air absorbs the engine heat. Expulsion of the hot air
takes place through one or more openings in the lower, aft portion of
the engine cowling.
Figure 21: Outside air aids in cooling the engine.
The outside air enters the engine compartment through an inlet behind
the propeller hub. Baffles direct it to the hottest parts of the engine,
primarily the cylinders, which have fins that increase the area exposed
to the airflow.
The air cooling system is less effective during ground operations,
takeoffs, go-arounds, and other periods of high-power, low-airspeed
operation. Conversely, high-speed descents provide excess air and can
shock-cool the engine, subjecting it to abrupt temperature fluctuations.
Operating the engine at higher than its designed temperature can cause
loss of power, excessive oil consumption, and detonation. It will also
lead to serious permanent damage, such as scoring the cylinder walls,
damaging the pistons and rings, and burning and warping the valves.
Monitoring the cockpit engine temperature instruments will aid in
avoiding high operating temperature.
Under normal operating conditions in airplanes not equipped with cowl
flaps, the engine temperature can be controlled by changing the airspeed
or the power output of the engine. High engine temperatures can be
decreased by increasing the airspeed and/or reducing the power.
The oil temperature gauge gives an indirect and delayed indication of
rising engine temperature, but can be used for determining engine
temperature if this is the only means available.
Many airplanes are equipped with a cylinder-head temperature gauge. This
instrument indicates a direct and immediate cylinder temperature change.
This instrument is calibrated in degrees Celsius or Fahrenheit, and is
usually color-coded with a green arc to indicate the normal operating
range. A red line on the instrument indicates maximum allowable cylinder
To avoid excessive cylinder head temperatures, increase airspeed, enrich
the mixture, and/or reduce power. Any of these procedures help in
reducing the engine temperature. On airplanes equipped with cowl flaps,
use the cowl flap positions to control the temperature. Cowl flaps are
hinged covers that fit over the opening through which the hot air is
expelled. If the engine temperature is low, the cowl flaps can be
closed, thereby restricting the flow of expelled hot air and increasing
engine temperature. If the engine temperature is high, the cowl flaps
can be opened to permit a greater flow of air through the system,
thereby decreasing the engine temperature.
Engine exhaust systems vent the burned combustion gases overboard,
provide heat for the cabin, and defrost the windscreen. An exhaust
system has exhaust piping attached to the cylinders, as well as a
muffler and a muffler shroud. The exhaust gases are pushed out of the
cylinder through the exhaust valve and then through the exhaust pipe
system to the atmosphere.
For cabin heat, outside air is drawn into the air inlet and is ducted
through a shroud around the muffler. The muffler is heated by the
exiting exhaust gases and, in turn, heats the air around the muffler.
This heated air is then ducted to the cabin for heat and defrost
applications. The heat and defrost are controlled in the cockpit, and
can be adjusted to the desired level.
Exhaust gases contain large amounts of carbon monoxide, which is
odorless and colorless. Carbon monoxide is deadly, and its presence is
virtually impossible to detect. The exhaust system must be in good
condition and free of cracks.
Some exhaust systems have an exhaust gas temperature probe. This probe
transmits the exhaust gas temperature (EGT) to an instrument in the
The EGT gauge measures the temperature of the gases at the exhaust
manifold. This temperature varies with the ratio of fuel to air entering
the cylinders and can be used as a basis for regulating the fuel/air
mixture. The EGT gauge is highly accurate in indicating the correct
mixture setting. When using the EGT to aid in leaning the fuel/air
mixture, fuel consumption can be reduced.
For specific procedures, refer to the manufacturer´s recommendations for
leaning the mixture.
This concludes the aircraft powerplant page. You can now go on to the
Auxiliary Aircraft Systems page or test your knowledge with the FAA
Principles of Flight question bank.
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