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Powerplant 2 > Fuel Systems and Control > Flashcards

Fuel Systems and Control Flashcards

(101 cards)

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1
Q

two-types of fuel system depending on the aircraft
design

A

gravity-feed system and pressure-feed system

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2
Q

The simplest form of aircraft fuel system is the ___________ used mainly by reciprocating engine aircraft

A

gravity-feed
system

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3
Q

A ____________ uses a pump to supply fuel to the engine

A

pressure-feed system

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4
Q

All ________ use fuel pumps.

A

turbine-powered aircraft

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5
Q

A ___________ must store, transfer, and meter fuel to
a turbine engine in the proper amount and at the right
pressure

A

turbine fuel system

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6
Q

_______ is required to eliminate fuel
metering problems caused by ice crystals in the fuel

A

fuel heater

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7
Q

Most large turbine aircraft fuel systems uses a
___________ that includes central refueling
provisions, and a means of transferring fuel between
tanks.

A

crossfeed system

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8
Q

Engine Fuel Systems Components

A

Fuel Storage/
Tanks

Fuel Delivery

Fuel Strainers/
Filters

Fuel Pumps Fuel

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9
Q

Maintaining fuel storage components in an ___________ is critical.

A

airworthy
condition

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10
Q

___________ (or
cells) can contaminate fuel, which can lead to damaged
components or restricted flow

A

Improperly maintained fuel tanks

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11
Q

Corrosion in fuel storage systems is a significant concern.
Even when corrosion-resistant materials are used, fuel
cells and related components are ___________

A

not corrosion-proof

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12
Q

Fuel tank construction varies significantly between types
of aircraft:

A

Integral
Rigid removable
Bladder

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13
Q

wet wings, cant be removed for
servicing/inspection

A

Integral

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14
Q

mostly made of metal, can be
removed for servicing/inspections

A

Rigid removable

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15
Q

Neopreneimpregnated fabrics, flexible and
more efficient. Heat/chemical/abrasion resistant

A

Bladder

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16
Q

are hoses constructed from synthetic materials like
Neoprene and Teflon because of their durability and
chemical resistance

A

Flexible Fuel Lines

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17
Q

In modern aircraft, flexible fuel lines
are hoses constructed from synthetic materials like
_____________ because of their durability and
chemical resistance

A

Neoprene and Teflon

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18
Q

Can be bent, but not twisted. Twisting weakens the part,
which leads to premature failure

A

Flexible Fuel Lines

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19
Q

To help identify a twisted
hose, most hoses are
manufactured with a __________

A

lay line.

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20
Q

may be constructed from a number of
materials, including copper, aluminum, and stainless steel

A

Rigid Fuel Lines

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21
Q

The majority of rigid fuel lines are constructed from
_____________.

A

5052-0 aluminum alloy

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22
Q

This material has good
corrosion resistance, is reasonably easy to fabricate, and
weighs less than materials of comparable strength.

A

5052-0 aluminum alloy.

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23
Q

____________ are typically used for manual engine
primer lines for carbureted engines.

A

Copper lines

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24
Q

____________is used when high temperatures
and corrosive conditions are present or high strength is
required.

A

Stainless steel tubing

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25
Regulations require that a ___________ (or fuel filter) be installed to remove contaminants and to provide a means to drain contaminants from the system
fuel strainer
26
___________ use both coarse and fine filter elements.
Most turbine engine fuel systems
27
A ____________is typically installed between the supply tank and the fuel pump, and a fine mesh filter is installed between the fuel pump and the fuel control unit
coarse mesh filter
28
Another type of filter uses _____________- a stack of wire mesh disks made from bronze, brass, or stainless steel
filter disks
29
This type of filter is reusable and well suited to withstand high operating pressures.
filter disks
30
meet the requirements for both coarse and fine filtration in a single unit.
Two-stage filters
31
The main fuel pump on all turbine engines is a positivedisplacement pump that is driven by the engine as an accessory.
Engine-DrivenPumps
32
A typical _____________ is designed to deliver a continuous supply of fuel to a fuel control unit in quantities that exceed the needs of the engine.
engine-driven pump
33
_____________ is returned to the tanks or another location ahead of the fuel pump inlet
Surplus fuel
34
Engine driven pumps are typically gear type pumps with _____________
one or two gear elements.
35
Some engine-driven fuel pumps also contain a _____________- that increases the fuel pressure.
centrifugal boost element
36
is installed at the outlet of each gear element to prevent fuel from draining out of the fuel system when the engine is shut down and to keep fuel from recirculating within a failed gear element
Check valve
37
is built into the pump housing to limit pump fuel pressure and provide protection to the fuel system.
pressure relief valve
38
An aircraft with an engine-driven pump is also equipped with an ___________ ( or boost pump) to maintain positive fuel pressure on the inlet side of the engine-driven fuel pump.
auxiliary fuel pump
39
This prevents pump cavitation and vapor lock.
auxiliary fuel pump
40
The __________ also provides fuel pressure for starting an engine and an alternate source of fuel pressure if the enginedriven fuel pump clogs or fails.
boost pump
41
In multiengine aircraft an ___________is often used to transfer fuel between tanks to redistribute fuel weight and maintain stability
auxiliary pump
42
Other types of boost pumps are ____________
centrifugal and pulsating electric pumps
43
Fuel Type for reciprocating engines
Aviation Gasoline
44
Fuel type for Gas Turbine Engines
Turbine Fuels
45
Turbine powered aircraft use a _____________ called "jet fuel."
kerosene-type fuel
46
Primary difference between types of jet fuel
JET A freezes at -40°C (-40°F). JET A-1 freezes at -47°C (-52.6°F). JET B freezes at -50°C (-58°F)
47
To determine which type of turbine fuel is approved for an engine;
check the engine type certificate data sheet or the aircraft specifications.
48
___________ is more viscous than _______-.
Jet fuel; avgas
49
The downside of this attribute is that jet fuel ______________ that does not easily settle into sumps.
holds water and solid material
50
These microorganisms tend to form _________ (or matted waste) inside fuel tanks that can accumulate and clog filters and fuel lines as well as corrode fuel cells.
slime
51
Many aircraft and engine manufacturers recommend the use of _____________
anti-icing and antimicrobial fuel additives.
52
is anti-icing fuel additive was developed to meet the high demands of the aviation industry.
PRIST® Hi-Flash
53
It is a commonly used additive containing both anti-icing and antimicrobial agents.
PRIST® Hi-Flash i
54
Other Turbine Engine Components
1.Fuel Transfer Ejectors 2.Fuel Heater 3.Water Injection Systems
55
is installed to eliminate and prevent the formation of ice crystals in the fuel supply.
fuel heater
56
A typical fuel heater consists of a ___________ that utilizes either engine oil or bleed air to warm the fuel.
heat exchanger
57
Manually operated fuel heating systems typically have operating restrictions. For example, fuel heat may be operated for _________ prior to takeoff, and then an additional minute during each successive _____________ of flight
one minute ; 30 minutes
58
____________ can cause vapor lock, and high temperature can damage the fuel control unit.
Improper use of fuel heat
59
Automatic systems are normally set to activate for fuel temperatures between_____________
35°F and 37°F.
60
used in some fuel systems to help the primary and/or boost pump scavenge fuel from a fuel tank and to facilitate the transfer of fuel from the main tank to a boost pump sump to help reduce unusable fuel and to balance the aircraft fuel load
Fuel Transfer Ejectors
61
The ejector is a tube with a constrictor that works on the _______
Bernoulli’s principle.
62
is a means of augmenting engine thrust in a gas turbine engine. In some cases, water injection may be used to cool the airflow and increase air density
Water injection
63
A typical water injection system uses a mixture of _____________
water and methanol
64
____________reduces turbine inlet temperature, but adding methanol counteracts this as it burns in the combustion chamber
Injecting water
65
The ________works as antifreeze to help prevent the water from freezing when the aircraft climbs to altitude.
methanol
66
Water may be injected directly into the _______, the ____________ just ahead of the ___________, or both the inlet and diffuser
compressor inlet; disffuser; combustion chamber
67
A___________must meter fuel to a turbine engine for reliable ground and air operations.
turbine engine fuel metering
68
The main components of a typical turbine engine fuel metering system include ___________-
a fuel control unit and fuel nozzles
69
Fuel control units meter the correct amount of fuel into the combustion section to obtain an optimum air-tofuel mixture ratio of _____________
15:1 by weight
70
meter the correct amount of fuel into the combustion section to obtain an optimum air-tofuel mixture ratio of 15:1 by weight.
Fuel control units
71
In turbine engines, fuel is metered by ________ rather than ___________.
weight rather than by volume
72
Remember that the __________ is the theoretically perfect mixture for combustion.
stoichiometric ratio of 15:1
73
are used on most turbojet and turbofan engines.
hydro-mechanical and electronic FCUs
74
are used on several turboprop engines
Hydro-pneumatic units
75
__________ is divided into a fuel metering section and a computing section.
hydromechanical fuel control unit
76
meter the appropriate amount of fuel to the combustion section at the correct pressure
fuel metering section of a hydromechanical fuel control unit
77
provide a positive means of stopping the flow of fuel to the engine for engine shut down
fuel shutoff valve
78
positioning the metering valve to obtain the appropriate power output and control the rate of acceleration and deceleration
computing section
79
It utilizes a pneumatic computing section that determines fuel flow rates based on the position of the power lever, N1 rpm, compressor discharge air (P3), and outside air pressure (Po)
Hydro-Pneumatic
80
To obtain precise monitoring and control needed in fuel metering, most modern turbofan engines utilize an ____________
electronic engine control
81
If the EEC fails, the engine reverts to mechanical control, which may reduce efficiency but keeps the engine operational.
SupervisoryEEC
82
Found in older-generation engines or those requiring failsafe mechanical redundancy.
SupervisoryEEC
83
performs virtually all the functions necessary to support engine operation during all phases of flight.
A full-authority digital engine control, or FADEC,
84
Sometimes referred to as fuel distributors, fuel nozzles are typically located in the diffuser or inlet of the combustion chamber where they deliver fuel in a specified quantity.
FuelNozzles
85
must mix the fuel with air and vaporize it as it enters the combustion chamber.
Fuel nozzles
86
receive fuel from a manifold, mix the fuel with air, and then deliver it to the combustor in an atomized spray pattern.
Atomizing fuel nozzles
87
The spray pattern is ________ and is designed to provide optimum fuel/air mixing as well as prevent the combustion flame from contacting the combustor lining.
cone shaped
88
used on early jet engines, provide a single spray pattern
SimplexNozzle
89
has two independent discharge orifices; one small and the other large.
Duplex Nozzle
90
it was developed to properly atomize fuel over a wide range of fuel flow rates.
Variable-Port Nozzle – also called Lubbock nozzle,
91
is basically a Simplex nozzle with a passage leading away from the spin chamber.
spill-type nozzle
92
– It used in some Rolls Royce engines. This type of atomizing nozzle differs from other nozzles in that there are openings in back of the nozzle that allow primary combustion airflow to aerate the fuel spray
Air-Spray Nozzle
93
pre-mixes the primary air and fuel in a vaporizing tube instead of delivering the fuel directly to the primary air in the combustor.
Vaporizing nozzles
94
have only one outlet vaporizing nozzle
Cane-Shaped Vaporizers –
95
utilizes two outlets
T-shaped Vaporizers –
96
Types of Vaporizing Nozzles
Cane-Shaped Vaporizers T-shaped Vaporizers
97
A shortcoming of vaporizing nozzles is that they do not provide an _________
effective spray pattern for starting
98
two-fold; first, the valve pressurizes the fuel in the primary and secondary fuel manifolds, and second, the valve empties, or dumps all the fuel in the two fuel manifolds upon engine shutdown.
Pressurization&DumpValve
99
prevent the residual engine heat from vaporizing the fuel in the fuel lines.
purpose of dumping all manifold fuel at engine shutdown
100
Fuel that is dumped during engine shutdown must be either ____________ or ____________
dumped into a separate storage tank or sent through a recovery system.
101
A system which neither recovers or burns dump fuel allows fuel to drain out of the lower nozzles and into the combustion chamber on shutdown.
DrainValves

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