FUEL SYSTEM Flashcards
1
Q
What is the freezing point of a fuel?
A
the temperature at which solid particales begin to from in the fuel
2
Q
How many microns are in one inch?
A
about 25,400
3
Q
How are aircraft engine fuels classified?
A
as inflammable liquids
4
Q
What is an inflammable material?
A
Any material that ignites easily and burns rapidly
5
Q
How do aircraft fuels compare to water in liquid form?
A
they are lighter than water
6
Q
How do aircraft fuels compare to air in vapor form?
A
they are heavier than air
7
Q
What must happen for fuel to burn or explode?
A
it must vaporize and the vapor be mixed in a given percentage of air
8
Q
What does the volatility of a fuel effect?
A
Starting, rage, and safety
9
Q
What characteristic of a fuel shows the tendency to vaporize at specific temperatures?
A
the vapor pressure
10
Q
What is measured by the distillation measurement for volatility?
A
the amount of fuel boiled off at specific temperatures
11
Q
What is the purpose of the fuel system?
A
to deliver a uniform of clean fuel under constant pressure to the engine under all operating conditions
12
Q
What are the 2 parts of the aircraft fuel system?
A
- the airframe fuel system consisting of fuel tanks, float-operated transfer valves, selector and shutoff valves, and fuel tank boost pumps
- The engine fuel system
13
Q
Who controls the emergency system that is not fully automatic?
A
the pilot
14
Q
What measures the ability of a liquid to convert to a vaporous state?
A
volatility
15
Q
How is the volatility of a petroleum fuel measured?
A
in terms of vapor pressure pressure and distillation
16
Q
How is vapor pressure measured?
A
In a Reid Vapor Pressure Test Bomb
17
Q
What is the flash point?
A
the temperature at which the fuel vaporizes enough to ignite with an outside heat source
18
Q
What flash point do ships require for storage for safety reasons?
A
140*F
19
Q
What is a calorie?
A
the amount of heat needed to raise the temperature of a 1 gram of water 1 degree celsius
20
Q
What is a BTU?
A
The amount of heat required to raise the temperature of 1 pound of water 1 degree Fahrenheit; 1 BTU=252 calories
21
Q
What is the internal resistance of a liquid that tends to prevent it from flowing?
A
Viscosity
22
Q
What must fuel have for satisfactory handling characteristics?
A
it should be noncorrosive and should not clog fuel filters, even at very low temperatures.
23
Q
What is slugging?
A
the process by which liquid fuel is carried along with vaporized fuel when the vapor escapes to the atomsphere
24
Q
How are U.S. Military grades of jet fuel designated>
A
JP followed by a number
25
What original herosene-type fuel used in turbine engines had characteristics of low vapor pressure and high energy content per volume of fuel?
JP-1
26
What has a fuel mixture of 65% gasoline and 35% kerosene?
JP-3
27
What fuel is an alternate fuel to JP-5 for USN jet aircraft used at shore stations only and is never used on ships?
JP-4 (NATO Code F-40)
28
What is the fuel density of JP-4?
6.5 LBS per gallon and is flash point is below 0*F
29
What fuel is the Navy's primary jet fuel?
JP-5
30
Which fuel is similar to JP-5 in most characteristics, except flash point and freeze point and is now available only in Europe?
JP-8 (NATO Code F-34)
31
What are the common commercial fuels used?
types A, A-1, and B
32
When are commercial fuels authorized for use in military aircraft?
When JP fuel is not available
33
How is commercial fuel characterized with military fuel?
A-1 is designated NATO code F-34, or equal to JP-8; Jet A is equal to JP-5 and Jet B is equal to JP-4
34
How do you determine how much contamination is too much?
by understanding the units of measurements used to identify contamination, which are mircons for solids and parts per million (ppm) for water
35
Since parts per million is the reference for water contamination, what happens if you take a 32oz. sample bottle and fill it 3 1/4 inches from the bottom?
you have about 500 cubic centimeters (cc); break the 500 down into one million little pieces and you now have 1 ppm
36
what is the color of jet fuel?
it varies from clear, water white to straw-yellow in color
37
What does a clean color of jet fuel mean?
the absence of any cloud, emulsion, visible sediment, or free water.
38
What does a bright color of jet fuel mean?
The fuel has a shiny, sparkling appearance
39
How is free water defined?
a cloud, emulsion, droplets, or gross amounts in the bottom of the container.
40
How is free water defined?
A cloud, emulsion, droplets, or gross amounts in the bottom of the container
41
What is the size of course sediment?
10 microns and fine sediments are less than 10 microns and are not visible as distinct or separate particles
42
What is the major constituent causing many of the problems associated with biological contamination of jet fuels?
fungus
43
What is fungus?
a vegetable life that holds rust and water and is a stabilizing agent for fuel-water emulsion
44
What is the color of microbiological growth?
Brown, black, or gray color and has a stringy, fibrous-like appearance.
45
What are the most commonly used types of self-sealing fuel cells?
the standard construction type and the type that uses a bladder along with the self-sealing cell.
46
When should samples of fuel be sent to the nearest Navy Petroleum Laboratory for microbiological growth determination?
if dark stringy or fibrous material tends that uses a bladder along with the self sealing cell
47
What is a self-sealing cell fuel container?
one that automatically seals small holes or damage caused during combat operations and is not bullet proof, merely, puncture sealing
48
Which fuel cell is used the most and is a semiflexible cell, made up of numerous plies of material?
the standard construction cell
49
What are the 2 parts of the combination bladder and self sealing cell?
One is a bladder-type cell and the other is identical to the standard construction cell.
50
What is the inner liner material used inside the self-sealing fuel cell made of?
Buna N synthetic rubber
51
What is the purpose of the inner liner material found inside of the self sealing fuel cell?
to contain the fuel and prevent if from coming in contact with the sealant
52
what is Buna rubber, an artificial substitute for crude or natural rubber, produced from?
Butadine and sodium
53
What is the purpose of the nylon fuel barrier?
to prevent the fuel from diffusing farther into the cell
54
What is the function of the sealant material?
it remains dormant in the fuel cell until the cell is ruptured of penetrated by a projectile then the sealant seals the ruptured area>
55
What is the purpose of the retainer?
to provide strength and support and also increases the efficiency of the mechanical action by returning the fuel cell to its original shape when punctured
56
What fuel cell is commonly called a bladder-type cell?
a nonself-sealing type
57
what are the 2 types of bladder-type fuel cells?
rubber type and nylon type
58
what is the purpose of the inner liner of the rubber-type bladder fuel cells?
to contain the fuel and provide protection for the nylon barrier
59
How is the nylon-type bladder cell (pliocel) identified?
by the trade name "Pliocel" stenciled on the outside of the cell
60
What does the pliocel construction consist of?
2 layers of nylon woven fabric laminated with 3 layers of transparent nylon film
61
what are the external fuel tanks that are droppable, streamlined, metal containers?
the 150- and 300- U.S. gallon AERO ID
62
What is provided on the top of the external fuel tanks to accommodate the installation of adapter fittings?
Threaded bosses and threaded inserts
63
what is the pressure-fueling float switch?
a float-operated device that accomplishes the shutoff of fuel flow when the external fuel tank is filled to capacity and is an electrical connector
64
What does the air pressure and vent shut valve use as a means of pressurizing the tank and forcing fuel into the wing tank, or tank store?
Engine bleed air
65
How is external fuel tank pressurization and transfer accomplished?
with regulated engine bleed air
66
What does an external tank pressure regulator maintain?
15 to 18 psi air pressure to each of the external tanks
67
What prevents the external fuel tanks from being pressurized while the aircraft is on the ground, during an arrested landing or during in-flight refueling?
The external tank air pressure regulator closes when there is weight on the wheels or when the in-flight refueling probe is extended
68
What does the airframe fuel system use to deliver a continuous supply of fuel to the engine(s) under all operating conditions?
Transfer pumps and boost pumps
69
What is the function of fuel transfer pumps?
they are installed in the fuel system to pump fuel from the various tanks of the aircraft to the main or sump tank
70
what fuel quantity gauge is normally used in aircraft?
an electronic (capacitor) type for measuring fuel in aircraft to the main or sump tank
71
Which valve is installed to shut off the fuel while a unit in the system in being removed or replaced?
the manually operated type
72
Which valve controls flow during fuel transfer and when fuel is being bypassed because of a defective or damaged unit?
Electrically operated shutoff valves
73
How is the lightweight how assembly identified?
by the bright wire braid outer cover with red markings, which are repeated 6 inches apart
74
What is the majority of the rigid tubing, used in naval aircraft, manufactured from?
Aluminum, however, exposed lines and lines subject to abrasion or intense heat are made of stainless
75
what is the last link between the airframe fuel system and the engine fuel system?
the engine fuel supply hose
76
what does the JFC 25-3 hydromechanical fuel control provide?
Automatic compensation through the full range of thrust for the ambient operating conditions encountered during flight
77
what are the variables sensed by the fuel control?
Automatic compensation through the full range of thrust for the ambient operating conditions encountered during flight
78
What are the variables sensed by the fuel control?
Power lever angle, burner pressure (Ps), High-pressure compressor speed (N2), and compressor inlet temperature (T ?)
79
What is the purpose of the JFC-25-2 computing system?
It senses and combines various operational parameters to govern the output of the metering system of the fuel control under all engine operating conditions
80
What is the N2 designation in the computing system of the JFC 25-3?
High pressure compressor rotor speed (RPM)
81
What is the Tt2 designation in the computing system of the JFC 25-3?
Compressor inlet temperature
82
What is the P/B designation in the computing system of the JFC 25-3?
Burner can pressure
83
What happens when low combustion chamber temperatures cause incomplete burning of fuel?
Carbonization occurs
84
What is the function of drain valves?
Drain residual fuel from the various parts of jet engines where accumulated fuel is mostly likely to present operating problems
85
How, in some instances, is the function of draining fuel manifolds accomplished?
by an individual unit known as a drip or dump valve
86
What is the function of the fuel spray nozzles in jet engines?
to inject fuel into the combustion area in a highly atomized, precisely patterned spray.
87
What does the drain valve allow when the fuel collects in the drain lines?
the fuel to drain when pressure in the combustion chamber manifold is reduced to near atmospheric pressure
88
Why is it important that the fuel be evenly distributed by the spray?
to prevent the formation of any hot spots in the combustion chambers
89
What does the duplex nozzle usually require?
a dual manifold and a pressurizing valve or flow divided to divide primary and secondary (main)fuel flow
90
What does the simple nozzle require?
only a single manifold for proper fuel delivery
91
Which nozzle the primary fuel line, of the duplex nozzle, (being smaller than the secondary line) permit?
fuel within the primary line to reach a comparatively high degree of pressure and atomization during starting and altitude idling conditions
92
what does the secondary fuel entry line permit?
starts supplying fuel when engine rpm raises fuel pressure to a predetermined level-usually after engine rpm is stabilized after a start
93
What are the 3 most common types of filters in use?
the microfilter, the wafer-screen filter and the plain screen mesh filter
94
Which filter has the greatest filtering action of any present day filter, and is rated in microns?
the micronfilter
95
What are the most widely used microfilters?
the 200-mesh and the 35-micron filters
96
What does the term positive displacement mean?
the pump will supply a fixed quantity of fuel to the engine
97
which pump has straight-line flow characteristics and fuel requirements that vary with flight or ambient air conditions?
The gear-type pump
98
What publications refers to fluid power?
NAVEDTRA 12964
99
What is the most important consideration in working with any fuel system maintenance task?
the safety of personnel
100
What are symptoms of inhalation of fuel vapors?
Nausea, dizziness, and headaches
101
How is the leak source analysis defined?
the process of using the aircraft maintenance manual, fuel system schematic diagrams, installation diagrams, and troubleshooting charts
102
What causes severe leaks in the tank/cell drain system?
a rupture, loose interconnecting fittings, or cut or distorted O-rings
103
How are leaks caused?
undertorquing or overtorquing lines, hoses, or fittings, and intermittent leaks are most often caused by loose cell fittings or connections
104
What is a practical means you can use to detect hidden fuel leaks in fuel system leak source analysis?
the use of colored dye
105
Where is the use of dyed fuel particularly useful?
near the engine's hot section where high temperature prevent the fuel from leaving a wet spot
106
What do you do if you use a dye to aid in the troubleshooting of fuel leaks?
A logbook entry in the miscellaneous history section of the aircraft logbook should be made and a similar entry should be made for aircraft serviced with dyed fuel
107
What is the measurement for the use of dye?
2oz. of dye for each 100 gallons of fuel in the cell or tank is required
108
What publication has the appropriate information for ordering the dye?
Appendix A of NA 01-1A-35
109
Why should the addition of unmixed bye to an empty fuel system always be avoided?
it can cause deterioration of the cell lining
110
why should colored fuel NOT be returned to bulk tanks or trucks?
because there is sufficient dye in a 2oz. can to color 10,000 gallons of fuel
111
Why is colored fuel suitable for use in aircraft engines?
Because the die does not have a harmful effect on the usefulness of the fuel
112
What action is taken before any maintenance is performed on a fuel tank/cell?
a check of the applicable aircraft maintenance manual is required
113
What action is taken if the aircraft maintenance manual is not specific enough to cover the type of maintenance that is required?
Refer to the AIRCRAFT FUEL CELL and INTERNAL/ECTERNAL manual, NA 01-1A-35
114
Which information do you use if you find conflicting information between the specific fuel system portion of the aircraft maintenance manual and the NA 01-1A-35
The procedures in the NA 01-1A-35 manual takes precedence
115
How is defueling defined?
the process of removing fuel from the aircraft tank/cell
116
How is depuddling defined?
the process or removing residual fuel from cells/tanks after defueling and low-point draining and is a necessary step prior to air purging when a nontoxic and noncombustible atmospheric state is required in a fuel cell or tank
117
How is purging defined?
the process for removing fuel vapors capable of producing a combustible or toxic atmosphere
118
What must be done before you perform any defueling, depuddling, or purging on an aircraft?
Park it in an area specifically authorized for such operations
119
What is required before the aircraft or defueler tanks are opened?
all the required grounding and bonding cables must be attached
120
When is defueling not allowed?
I the vicinity of an electrical storm and no maintenance of any type will be allowed on the aircraft during refueling
121
Why is depuddling of the aircraft fuel tank/cell a hazardous operation?
Because it requires the entry or partial entry of personnel into an aircraft tank/cell; all maintenance personnel are required to work in pairs
122
What are the general safety precautions that apply to depuddling?
The aircraft battery connector and aircraft power receptacle should always be tagged with an appropriate warning placard to indicate power is not to be applied to the aircraft uner any circumstances
123
What is the procedure when you purge a tank/cell?
attach an approved air blower to the tank/cell and ensure that all personal remain clear of the removed access panel; allow approzimately 30 minutes for the blower to remove the toxic vapors, stop the air blower and have the tank cell tested by a gas-free engineer to ensure the tank/cell is safe for personnel to initiate depuddling
124
How much time is needed if a "safe" condition is not reached when purging a tank/cell?
reinstall the air blower for at least an additional 15 minutes and have the test repeated.
125
What are the four approved methods you may use to purge the aircraft fuel tank/cell?
1. Air blow
2. Air exhaust
3. oil purge
4. JP-5 method
126
What lubricating oil does the purge method use to dilute the fuel vapors in a defueled tank/cell?
MIL-L-6081, grade 1010
127
How long will the oil purge method normally keep the tank/cell safe for personnel?
Approximately 10 to 15 days
128
What is mandatory in all methods of purging a tank/cell?
the tank/cell be certified, which is done by a gas-free engineer and documented as being safe for personnel or safe for hotwork
129
What oil is applied when a fuel cell remains empty for more than 72 hours?
a thin coat of specification MIL-L-6081, grade 1010, is applied to the interior of the cell
130
What oil should fuel cells that are to be returned to storage until repairs can be accomplished, have?
Specification MIL-L-6082, grade 1065 and is applied to the interior of the cell
131
What should be done if a fuel cell is to be removed during cold weather?
Warm the cell to at least to at least 60*F (16*c) before collapsing or folding
132
What oil should be applied when a fuel tank remains empty for more than 72 hours?
A thin coat of MIL-L-6081, grade 1010 an should be applied to the inner liner
133
When do Pliocel-type bladder cells require internal preservation?
When they are folded and stored for a period in excess of 2 weeks
134
What must be done if the Pliocel-type cell becomes necessary to preserve?
the inner lining must be coated with equal parts of glycerin, MIL-G-491, and water applied by a cheesecloth soaked in the solution.
135
What happens to fuel cells that have been stored for a longtime?
they shrink or become distorted and will be difficult for you to install, ad they often cause misalignment of the cell fittings with aircraft fittings
136
How are shrunken or distorted fuel cells restored?
Soak the cell in water and the length of time required for soaking will normally depend on the condition of the cell
137
How long does the soaking of a shrunken or distorted fuel cell normally take?
72 hours, as long as the water temperature remains at least 70*F
138
How may soaking time be reduced for a shrunken or distorted fuel cell?
Place the cell in an air-circulating oven at a maximum temperature of 120*F for about 4 hours, also must be maintained at high humidity
139
What is applied to the outer surface of a fuel cell and the cell cavity to make it easier to move the cell into position?
Tale or other suitable powder
140
When may fuel seal compounds be used?
On connections when the adjoining surfaces are metal; NEVER on rubber fuel fittings
141
Why must the main-line strainer be drained at each preflight inspection?
to eliminate any water and/or sediment
142
How often in the ram air turbine, hose, and reel inspected on the model D-704 air refueling store?
every 10 hours of reel operation
143
What must be removed before performing any maintenance on the D-704 air refueling store?
the hose jettison cartridge
144
What is the minimum flow or fuel observed on the D-704 air refueling store control panel?
40 gallons in 15 seconds (160 GPM) if JP-5 fuel is used and 37.5 gallons in 15 seconds (150 GPM) if MIL-L-6081C (1010) oil is used
145
What parts make up the control system and must be adjusted or rigged from time to time?
Bell cranks, push-pull rods, drums, fairleads, flexible cables, and sheaves
