Fuel Systems and Control Flashcards by GUNAYON, Mark C.

The entire system which stores,
carries, and controls the fuel supply
for the engines can be divided into
two sections. These are:

airframe fuel system
engine fuel system

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receives the
low pressure fuel supply from the
aircraft fuel tanks which are part of
the airframe fuel system.

engine fuel system

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increases the
fuel pressure to a value that the fuel
nozzles in the combustion chamber
can use with the use of fuel pump,
and then controls the volume of fuel
into the engine with the use of fuel
control unit into the engine so that it
conforms to the engine’s
requirement.

engine fuel system

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situated in the wing, pass fuel
through non-return valves to the
engine via the low pressure fuel cock.

booster pumps

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can be
used to shut off the supply of fuel to
the engine to facilitate the removal of
fuel system components.

low pressure fuel cock

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Using the low pressure fuel cock to
shut down the engine, instead of the
high pressure fuel cock, will mean
that the engine will take much
shorter/longer to shutdown.

longer

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sometimes called the backing pump,
backs up the fuel supply to the
engine in the event of failure of the
booster pumps in the wing tanks.

low pressure fuel pump

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the low pressure fuel pump is sometimes called the

backing pump

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maintain a positive pressure at the
inlet of the high pressure pump.

low pressure fuel pumps

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serves the
double purpose of cooling the oil and
also heating the fuel.

fuel cooled air cooler

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these may block component downstream in the fuel system

formation of ice crystals

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incorporates a
valve to maintain the oil pressure in
the cooler higher than the fuel
pressure. This ensures that, in the
case of an internal leak, oil leaks into
the fuel system rather than fuel
leaking into the oil system.

oil cooler feed line

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working in
conjunction with the fuel cooled air
cooler, uses compressor bleed air to
warm the fuel to automatically
maintain a predetermined fuel
temperature.

fuel heater

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used to open or close a valve which
regulates the entry of hot air into the
fuel heater from the engine
compressor.

automatic temperature control

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protects the HP fuel
pump and the fuel control unit from
the effects of dirt or contamination.

LP fuel filter

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The filter of an LP fuel filter is a replaceable paper filter
element which is capable of filtering
out particles larger than

50 to 100 microns

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measures the
instantaneous fuel flow in gallons per
hour, kilograms per hour, or pounds
per hour, and may also include an
________ which can add
the total amount of fuel used.

flowmeter; integrating system

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fitted to and
driven by the engine accessory
gearbox. The engine accessory
gearbox itself is driven by the

HP fuel pump; HP compressor shaft

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are rotated
against a stationary camplate which
causes them to reciprocate within
the bores that contain them on the
rotor assembly.

plungers

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The distance that the plungers move
during this reciprocating action is
dictated by the

angle of inclination of camplate

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controlled by a servo
piston which itself is controlled from
the fuel control unit.

angle of inclination of the camplate

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the angle of inclination of the camplate is controlled by a _______ which itself is controlled from
the fuel control unit.

servo piston

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composed of a
number of wire mesh screen disks, is
incorporated in the output of the
high pressure fuel pump.

filter

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is
simpler and lighter in construction
than the plunger type, and is also
driven by the accessory gearbox.

Study These Flashcards

spur gear type fuel pump

The output of the spur gear pump is directly proportional to its

rotational speed

types of HP fuel pump

1. plunger 2. spur gear type fuel pump

controls the fuel flow to the burners for every thrust setting.

fuel control unit/system

is maintained for a selected throttle position at all altitudes and airspeeds.

fixed rpm

A fixed rpm is maintained for a selected throttle position at all altitudes and airspeeds. This is achieved by the ________, which in turn modifies the fuel flow to suit the new conditions.

expansion or contraction of the Barometric Pressure Capsule by P1 pressure

receives P1 and P3 information. It uses information to adjust a fuel metering plunger which prevents stall or surge by regulating the fuel flow during engine acceleration.

acceleration control unit

allows for full power to be selected at any time without risking a meltdown in the turbine assembly.

top temperature control unit

are positioned in the gas stream either within the turbine assembly or close after it. The output is used to measure the temperature at the rear of the engine.

thermocouple probes

The output of the amplifier drives a _______ which indirectly controls the fuel flow to the engine.

solenoid

To prevent compressor casing failure, the fuel control unit incorporates a _______ device.

power limiter

receives signals of both intake pressure (P1), and compressor delivery pressure (P3).

power limiter

The ratio of P3 to P1 can be found by _______ these signals.

combining

are used to limit compressor rotational speed in order to prevent excessive centrifugal force.

rpm limiter

2 methods of rpm limiting

1. depends on a shaft speed sensor being sent to an amplifier 2. involves hydro-mechanical governor which uses hydraulic pressure as the controlling parameter

controls the flow of fuel between the fuel control unit and the fuel spray nozzles in the combustion chambers.

HP fuel cock

is the control normally used for starting or stopping the fuel supply to the engine.

HP fuel cock

Two types of electronic engine control, which enable better fuel economy, better reliability, and prolonged engine life, are currently in use. They are:

1. Supervisory Engine Control System 2. Full Authority Digital Engine Control System

uses a computer which receives inputs of various engine operating parameters and controls a standard hydro-mechanical fuel control unit.

supervisory engine control system

It monitors EPR, throttle lever angle, Mach No., engine intake pressure, and temperature, and will remain a constant thrust regardless of changes in air pressure, temperature, or flight environment.

supervisory engine control syste

receives all necessary data for engine operation and takes over virtually all of the steady state and transient control functions, which includes compressor airflow control.

full authority digital engine control system (FADEC)

will prevent engine limitations being exceeded, and controls the engine in response to the throttle lever position.

full authority digital engine control system (FADEC)

devices on fuel control unit/system

1. altitude control 2. acceleration control 3. top temperature control 4. power limiter 5. rpm limiter 6. HP fuel cock 7. electronic engine control 8. supervisory engine control system 9. full authority digital engine control system (FADEC)

have the task of atomizing or vaporizing the fuel to ensure that it is completely burnt.

fuel spray nozzles

At engine start, when there is a low RPM and low fuel pressure, the fuel spray pattern forms what is known as a _______. This spray pattern does not atomize the fuel jet sufficiently for ignition to occur.

bubble

As the engine accelerates, the pump rotates faster and builds up more pressure until the spray pattern forms a

tulip shape

these effectively use an orifice of variable size. At low pressures, a pressurizing valve closes off the main fuel feed to the nozzle, the only supply coming from the primary fuel line.

duplex and duple spray nozzles

feeds the primary orifice which is capable of providing a finely atomized spray at lower fuel pressures.

primary fuel line

When the engine accelerates during start, _______ builds until the pressurizing valve starts to open. This allows fuel to flow through the main orifice, where it supplements the spray from the primary orifice.

fuel pressure

Gas turbine engines are powered by ________ because it was more available than gasoline.

kerosene

After the war, the United States Air Force started using a fuel in gas turbine engines which spanned the gasoline and kerosene boiling ranges. This fuel was called the ________ which stemmed from catalyzing process from which the fuel could be taken.

wide cut fuel

this wide cut fuel is still available in some parts of Alaska and Canada, because it is suited to cold climates.

Jet B

In the remainder of North America, this kerosene-type fuel is used because of its lower cost and better availability.

Jet A

In the rest of the world, this kerosene-type fuel, predominates. It has a higher freezing point than Jet A, which makes it suitable for use on long international flights.

Jet A-1

advantage of Jet A-1 over Jet A fuel

It has a higher freezing point than Jet A, which makes it suitable for use on long international flights.

Eastern Europe use ________, which is also a light kerosene-type fuel.

Russian fuel, TS-1

Fuel Systems and Control Flashcards

(59 cards)