Topic 04 - Fuel Systems and Control Flashcards
the entire system which stores, carries, and controls the fuel supply for the engines
fuel system
sections of a fuel system
- airframe fuel system
- engine fuel system
responsible for transferring the fuel from the tanks to the engine for usage
airframe fuel system
the __________________ receives the low pressure fuel supply from the aircraft fuel tanks which are part of the __________________
engine fuel system, airframe fuel system
the engine fuel system ____________ the fuel pressure to a value that the fuel nozzles in the combustion chamber can use with the use of ___________
increases, fuel pump
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 ________________
fuel control unit, engine’s requirement
the ______________ which are situated in the wing pass fuel through non-return valves to the engine via the ________________
booster pumps, low pressure fuel cock
the ____________________ can be used to shut off the supply of fuel to the engine to facilitate the removal of ___________________
low pressure fuel cock, fuel system components
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
low pressure, high pressure
after passing through the low pressure fuel cock, the fuel is delivered to the ___________________
low pressure fuel 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
another name for the low pressure fuel pump
backing pump
the low pressure fuel pumps maintain a ________________ at the inlet of the high pressure pump
positive pressure
serves the double purpose of cooling the oil and also heating the fuel
fuel cooled oil cooler
by raising the temperature of the fuel, the formation of ____________, which may block components downstream in the fuel system, is eliminated
ice crystals
the _________________ incorporates a valve to maintain the oil pressure in the cooler is higher than the fuel pressure
oil cooler feed line
what ensures that, in the case of an internal leak, oil leaks into the fuel system rather than fuel leaking into the oil system?
the oil pressure in the cooler is higher than the fuel pressure
the fuel heater uses __________________ to warm the fuel to automatically maintain a predetermined fuel temperature
compressor bleed air
what component works in conjunction with the fuel cooled air cooler?
fuel heater
the ___________________ is used to open or close a valve which regulates the entry of hot air into the _____________ from the engine compressor
automatic temperature control, fuel heater
the automatic temperature control is assisted by an actuator called _____________ which incorporates a material that is sensitive to temperature changes
vernatherm
the ___________ protects the HP fuel pump and the fuel control unit from the effects of dirt or contamination
LP fuel filter
the LP fuel filter is a _______________ filter element which is capable of filtering out particles larger than ___________________
replaceable paper, 50 to 100 microns
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
instantaneous fuel flow, add the total amount
two types of flowmeter
- vane type
- mass flow type
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
vane type
a type of flowmeter that uses magnets and the difference between the angular displacement will translate into the mass flow rate of the fuel
mass flow type
the HP fuel pump is fitted to and driven by the __________________
engine accessory gearbox
the engine accessory gearbox itself is driven by the ___________________
HP compressor shaft
two types of high pressure fuel pump
- plunger type
- spur gear type
in a plunger type high pressure fuel pump, the plungers are fitted on a _________________
rotor assembly
what causes the plungers to reciprocate within the bores that contain them on the rotor assembly when rotated against it?
stationary camplate
the distance that the plungers move during the reciprocating action is dictated by the _____________ of camplate
angle of inclination
the angle of inclination of the camplate is controlled by a ____________ which itself is controlled from the _____________
servo piston, fuel control unit
plunger type: a filter, which is composed of a number of _____________________, is incorporated in the output of the high pressure fuel pump
wire mesh screen disks
which of the two types of high pressure fuel pump is simpler and lighter in construction than the other?
spur gear type fuel pump
the spur gear type fuel pump is driven by the ____________
accessory gearbox
the output of the spur gear pump is directly proportional to its _______________
rotational speed
the _______________ controls the fuel flow to the burners for every thrust setting
fuel control unit
the two types of fuel control unit is of which system?
hydromechanical system
two types of fuel control unit
- pressure control system
- proportional flow control system
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?
proportional flow control system
various devices within the fuel control unit are used to adjust fuel flow to cater for variations in what?
- air intake pressure
- engine acceleration control
- exhaust gas temperature
- RPM limiting
- compressor delivery pressure
indicators of the different properties of air along the length of the gas turbine engine
engine station numbers
engine station numbers and meaning
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
parts of a fuel control unit
- altitude control
- acceleration control
- top temperature control
- power limiter
- RPM limiter
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
fixed rpm, Barometric Pressure Capsule by P1 pressure
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
acceleration control unit, stall or surge
the ______________________ 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 and the output is used to measure the ______________ at the rear of the engine
thermocouple probes, temperature
the output of the thermocouple probe is passed both to ___________________ and to a ____________________
cockpit instrumentation, temperature control signal amplifier
the output of the temperature control signal 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
the power limiter receives signals of both ______________, and ___________________ and the ratio of __________ can be found by combining these signals
intake pressure (P1), compressor delivery pressure (P3), P3 to P1
used to limit compressor rotational speed in order to prevent excessive centrifugal force
RPM limiter
two methods used by an RPM limiter
- 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
the ______________ controls the flow of fuel between the fuel control unit and the fuel spray nozzles in the combustion chambers
HP fuel cock
the ____________ is the control normally used for starting or stopping the fuel supply to the engine
HP fuel cock
this component enables better fuel economy, better reliability, and prolonged engine life
electronic engine control
two types of electronic engine control
- supervisory engine control system
- full authority digital engine control system
the ____________________ uses a computer which receives inputs of various engine operating parameters and controls a standard ________________________
supervisory engine control system, hydro-mechanical fuel control unit
the supervisory engine control system monitors what?
- EPR
- throttle lever angle
- Mach No.
- engine intake pressure
- temperature
the supervisory engine control system maintains a constant thrust regardless of changes in what?
- air pressure
- temperature
- flight environment
what does FADEC mean?
full authority digital engine control
the _________ receives all necessary data for engine operation and takes over virtually all of the ____________ and _____________ functions, which includes compressor airflow control
FADEC, steady state, transient control
__________ will prevent engine limitations being exceeded, and controls the engine in response to the throttle lever position
FADEC
the very high combustion efficiency attained in modern gas turbine engines is partly due to the __________________
fuel spray nozzles
task of the fuel spray nozzles
atomizing or vaporizing the fuel to ensure that it is completely burnt
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
bubble
as the engine accelerates, the pump rotates faster and builds up more pressure until the fuel spray pattern forms a ________ shape
tulip
fuel spray: eventually, the pump produces sufficient pressure to shorten the tulip until it touches the __________
orifice
two types of fuel spray nozzle
- simplex
- duplex
the duplex and duple spray nozzles, effectively use an orifice of _____________
variable size
duplex spray nozzle: at low pressures, a pressurizing valve closes off the ______________ to the nozzle, the only supply coming from the ________________
main fuel feed line, primary fuel line
how does the duplex spray nozzle work?
- 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
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 which was called the ‘__________’ fuel which stemmed from catalyzing process from which the fuel could be taken
wide cut
________________, is still available in some parts of Alaska and Canada, because it is suited to cold climates
Jet B, wide cut fuel
in the remainder of North America, _______, which is a _________________, is used because of its lower cost and better availability
Jet A, kerosene-type fuel
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
Jet A-1, kerosene-type fuel
Eastern Europe use _________________,which is a ______________________
Russian fuel, TS-1; light kerosene-type fuel
Jet B fuel is also called
avtag or aviation turbine gasoline
Jet A-1 fuel is also called
avtur o aviation turbine fuel
