Topic 04 - Fuel Systems and Control

Question 1

the entire system which stores, carries, and controls the fuel supply for the engines

Answer 1

fuel system

Question 2

sections of a fuel system

Answer 2

• airframe fuel system
• engine fuel system

Question 3

responsible for transferring the fuel from the tanks to the engine for usage

Answer 3

airframe fuel system

Question 4

the __________________ receives the low pressure fuel supply from the aircraft fuel tanks which are part of the __________________

Answer 4

engine fuel system, airframe fuel system

Question 5

the engine fuel system ____________ the fuel pressure to a value that the fuel nozzles in the combustion chamber can use with the use of ___________

Answer 5

increases, fuel pump

Question 6

the engine fuel system controls the volume of fuel into the engine with the use of ______________ into the engine so that it conforms to the ________________

Answer 6

fuel control unit, engine’s requirement

Question 7

the ______________ which are situated in the wing pass fuel through non-return valves to the engine via the ________________

Answer 7

booster pumps, low pressure fuel cock

Question 8

the ____________________ can be used to shut off the supply of fuel to the engine to facilitate the removal of ___________________

Answer 8

low pressure fuel cock, fuel system components

Question 9

using the ____________ fuel cock to shut down the engine, instead of the _______________ fuel cock, will mean that the engine will take much longer to shutdown

Answer 9

low pressure, high pressure

Question 10

after passing through the low pressure fuel cock, the fuel is delivered to the ___________________

Answer 10

low pressure fuel pump

Question 11

backs up the fuel supply to the engine in the event of failure of the booster pumps in the wing tanks

Answer 11

low pressure fuel pump

Question 12

another name for the low pressure fuel pump

Answer 12

backing pump

Question 13

the low pressure fuel pumps maintain a ________________ at the inlet of the high pressure pump

Answer 13

positive pressure

Question 14

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

Answer 14

fuel cooled oil cooler

Question 15

by raising the temperature of the fuel, the formation of ____________, which may block components downstream in the fuel system, is eliminated

Answer 15

ice crystals

Question 16

the _________________ incorporates a valve to maintain the oil pressure in the cooler is higher than the fuel pressure

Answer 16

oil cooler feed line

Question 17

what ensures that, in the case of an internal leak, oil leaks into the fuel system rather than fuel leaking into the oil system?

Answer 17

the oil pressure in the cooler is higher than the fuel pressure

Question 18

the fuel heater uses __________________ to warm the fuel to automatically maintain a predetermined fuel temperature

Answer 18

compressor bleed air

Question 19

what component works in conjunction with the fuel cooled air cooler?

Answer 19

fuel heater

Question 20

the ___________________ is used to open or close a valve which regulates the entry of hot air into the _____________ from the engine compressor

Answer 20

automatic temperature control, fuel heater

Question 21

the automatic temperature control is assisted by an actuator called _____________ which incorporates a material that is sensitive to temperature changes

Answer 21

vernatherm

Question 22

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

Answer 22

LP fuel filter

Question 23

the LP fuel filter is a _______________ filter element which is capable of filtering out particles larger than ___________________

Answer 23

replaceable paper, 50 to 100 microns

Question 24

the flowmeter measures the ____________________ in gallons per hour, kilograms per hour, or pounds per hour, and may also include an integrating system which can __________________ of fuel used

Answer 24

instantaneous fuel flow, add the total amount

Question 25

two types of flowmeter

Answer 25

- vane type - mass flow type

Question 26

a type of flowmeter where a component is moved against the force of a restraining spring by the volume of the fuel that flows past it

Answer 26

vane type

Question 27

a type of flowmeter that uses magnets and the difference between the angular displacement will translate into the mass flow rate of the fuel

Answer 27

mass flow type

Question 28

the HP fuel pump is fitted to and driven by the __________________

Answer 28

engine accessory gearbox

Question 29

the engine accessory gearbox itself is driven by the ___________________

Answer 29

HP compressor shaft

Question 30

two types of high pressure fuel pump

Answer 30

- plunger type - spur gear type

Question 31

in a plunger type high pressure fuel pump, the plungers are fitted on a _________________

Answer 31

rotor assembly

Question 32

what causes the plungers to reciprocate within the bores that contain them on the rotor assembly when rotated against it?

Answer 32

stationary camplate

Question 33

the distance that the plungers move during the reciprocating action is dictated by the _____________ of camplate

Answer 33

angle of inclination

Question 34

the angle of inclination of the camplate is controlled by a ____________ which itself is controlled from the _____________

Answer 34

servo piston, fuel control unit

Question 35

plunger type: a filter, which is composed of a number of _____________________, is incorporated in the output of the high pressure fuel pump

Answer 35

wire mesh screen disks

Question 36

which of the two types of high pressure fuel pump is simpler and lighter in construction than the other?

Answer 36

spur gear type fuel pump

Question 37

the spur gear type fuel pump is driven by the ____________

Answer 37

accessory gearbox

Question 38

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

Answer 38

rotational speed

Question 39

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

Answer 39

fuel control unit

Question 40

the two types of fuel control unit is of which system?

Answer 40

hydromechanical system

Question 41

two types of fuel control unit

Answer 41

- pressure control system - proportional flow control system

Question 41

which of the two types of fuel control unit is more popular and more compact than the other and is not sensitive to flow variations downstream of the throttle?

Answer 41

proportional flow control system

Question 42

various devices within the fuel control unit are used to adjust fuel flow to cater for variations in what?

Answer 42

- air intake pressure - engine acceleration control - exhaust gas temperature - RPM limiting - compressor delivery pressure

Question 43

indicators of the different properties of air along the length of the gas turbine engine

Answer 43

engine station numbers

Question 44

engine station numbers and meaning

Answer 44

0 - free stream 1 - intake entrance 2 - intake exit and compressor entrance 3 - compressor exit and burner entrance 4 - burner exit and turbine entrance 5 - turbine exit 6 - upstream of the afterburner 7 - nozzle entrance 8 - nozzle throat

Question 45

parts of a fuel control unit

Answer 45

- altitude control - acceleration control - top temperature control - power limiter - RPM limiter

Question 46

a ___________ is maintained for a selected throttle position at all altitudes and airspeeds and is achieved by the expansion or contraction of the _______________________, which in turn modifies the fuel flow to suit the new conditions

Answer 46

fixed rpm, Barometric Pressure Capsule by P1 pressure

Question 47

an __________________ is fitted which receives P1 and P3 information and uses it to adjust a fuel metering plunger which prevents _____________ by regulating the fuel flow during engine acceleration

Answer 47

acceleration control unit, stall or surge

Question 48

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

Answer 48

top temperature control unit

Question 49

___________________ are positioned in the gas stream either within the turbine assembly or close after it and the output is used to measure the ______________ at the rear of the engine

Answer 49

thermocouple probes, temperature

Question 50

the output of the thermocouple probe is passed both to ___________________ and to a ____________________

Answer 50

cockpit instrumentation, temperature control signal amplifier

Question 51

the output of the temperature control signal amplifier drives a ___________ which indirectly controls the fuel flow to the engine

Answer 51

solenoid

Question 52

to prevent compressor casing failure, the fuel control unit incorporates a ‘______________’ device

Answer 52

power limiter

Question 53

the power limiter receives signals of both ______________, and ___________________ and the ratio of __________ can be found by combining these signals

Answer 53

intake pressure (P1), compressor delivery pressure (P3), P3 to P1

Question 54

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

Answer 54

RPM limiter

Question 55

two methods used by an RPM limiter

Answer 55

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

Question 56

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

Answer 56

HP fuel cock

Question 57

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

Answer 57

HP fuel cock

Question 58

this component enables better fuel economy, better reliability, and prolonged engine life

Answer 58

electronic engine control

Question 59

two types of electronic engine control

Answer 59

- supervisory engine control system - full authority digital engine control system

Question 60

the ____________________ uses a computer which receives inputs of various engine operating parameters and controls a standard ________________________

Answer 60

supervisory engine control system, hydro-mechanical fuel control unit

Question 61

the supervisory engine control system monitors what?

Answer 61

- EPR - throttle lever angle - Mach No. - engine intake pressure - temperature

Question 62

the supervisory engine control system maintains a constant thrust regardless of changes in what?

Answer 62

- air pressure - temperature - flight environment

Question 63

what does FADEC mean?

Answer 63

full authority digital engine control

Question 64

the _________ receives all necessary data for engine operation and takes over virtually all of the ____________ and _____________ functions, which includes compressor airflow control

Answer 64

FADEC, steady state, transient control

Question 65

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

Answer 65

FADEC

Question 66

the very high combustion efficiency attained in modern gas turbine engines is partly due to the __________________

Answer 66

fuel spray nozzles

Question 67

task of the fuel spray nozzles

Answer 67

atomizing or vaporizing the fuel to ensure that it is completely burnt

Question 68

at engine start, when there is a low RPM and low fuel pressure, the fuel spray pattern forms what is known as a ________, which is a spray pattern that does not atomize the fuel jet sufficiently for ignition to occur

Answer 68

bubble

Question 69

as the engine accelerates, the pump rotates faster and builds up more pressure until the fuel spray pattern forms a ________ shape

Answer 69

tulip

Question 70

fuel spray: eventually, the pump produces sufficient pressure to shorten the tulip until it touches the __________

Answer 70

orifice

Question 71

two types of fuel spray nozzle

Answer 71

- simplex - duplex

Question 72

the duplex and duple spray nozzles, effectively use an orifice of _____________

Answer 72

variable size

Question 73

duplex spray nozzle: at low pressures, a pressurizing valve closes off the ______________ to the nozzle, the only supply coming from the ________________

Answer 73

main fuel feed line, primary fuel line

Question 74

how does the duplex spray nozzle work?

Answer 74

- at lower fuel pressures, the primary fuel line feeds the primary orifice - as the engine accelerates during start, fuel pressure builds until the pressurizing valve starts to open allowing fuel to flow through the main orifice, where it supplements the spray from the primary orifice

Question 75

gas turbine engines are powered by ___________ because it was more available than gasoline

Answer 75

kerosene

Question 76

after the war, the United States Air Force started using a fuel in gas turbine engines which spanned the gasoline and kerosene boiling ranges which was called the ‘__________’ fuel which stemmed from catalyzing process from which the fuel could be taken

Answer 76

wide cut

Question 77

________________, is still available in some parts of Alaska and Canada, because it is suited to cold climates

Answer 77

Jet B, wide cut fuel

Question 78

in the remainder of North America, _______, which is a _________________, is used because of its lower cost and better availability

Answer 78

Jet A, kerosene-type fuel

Question 79

in the rest of the world, ________, which is a __________________, predominates because it has a higher freezing point than Jet A, which makes it suitable for use on long international flights

Answer 79

Jet A-1, kerosene-type fuel

Question 80

Eastern Europe use _________________,which is a ______________________

Answer 80

Russian fuel, TS-1; light kerosene-type fuel

Question 81

Jet B fuel is also called

Answer 81

avtag or aviation turbine gasoline

Question 82

Jet A-1 fuel is also called

Answer 82

avtur o aviation turbine fuel