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M11 COPY > 11.10 Fuel Systems > Flashcards

11.10 Fuel Systems Flashcards

1
Q

What are the four main types of turbine engine fuels

A

Jet A1
Jet A
Jet B
JP 5

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2
Q

What is the flash and freezing point of Jet A1 fuel

A

38 degrees C

-47 degrees C

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3
Q

Flash and freezing point of Jet A

A

38 degrees C

-40 degrees C

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4
Q

Flash and freezing point of Jet B fuel

A
  • 20 degrees C

- 58 degrees C

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5
Q

Main requirements of turbine engine fuels

A

Low freezing point and flash point low enough to provide good ignition capabilities but high as possible for safe fuel handling

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6
Q

At a temperature of 15 degrees C what is the density of Jet A1 and Jet A fuel

A

0.81kg/ltr

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7
Q

Density of Jet B at 15 degrees C

A

0.78kg/ltr

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8
Q

What requirements are their for fuel characteristics? (3)

A

✈️Adequate lubrication
✈️low tendency to hold water
✈️widely available worldwide

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9
Q

What are the dangers of water in fuel and fuel tanks? (6)

A
  • Encourages ice build up
  • Supports corrosion
  • Engine power fluctuations
  • Engine flame outs
  • irregular fuel level indications
  • Microbial growth in tanks
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10
Q

What is the most common method to test for water in fuel

A

Syringe test - fuel passes through filter, filter changes colour if fuel contains water

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11
Q

What does the fuel storage system consist of

A

Fuel tanks
Tank drain system
Tank vent system

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12
Q

Where can fuel tanks be found

A

Wings
Centre fuselage
Horizontal stabilisers
Cargo compartments

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13
Q

On which aircraft does there have to be space for reserve fuel

A

All aircraft

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14
Q

What are vent surge tanks used for

A

Help make sure fuel tanks are properly vented

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15
Q

What purpose do trim tanks serve as well as storing fuel?

A

Used to trim the Aircraft

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16
Q

What is the most common type of fuel tank used on modern jet aircraft and why

A

Integral tanks - weight saving

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17
Q

How do integral tanks save weight on aircraft

A

Parts of the aircraft structure are used as tank walls

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18
Q

How are integral tanks made leak tight

A

Fillet seal where two plates join and cap seals to cover nuts and bolts

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19
Q

What type of tank has a light metal alloy outer housing and a flexible rubber bladder

A

Bladder type fuel tank

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20
Q

How is fuel movement dampened

A

Ribs in the wing and non sealing divider walls

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21
Q

Why does fuel movement need to be dampened

A

Fuel splashing around during attitude changes would make the aircraft unstable

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22
Q

What does a flap baffle check valve ensure

A

There is enough fuel for the fuel boost pumps by preventing fuel from flowing out of the collector box

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23
Q

What provides the metal contact between the access door and aircraft structure?

A

Knit Aluminium Gasket

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24
Q

What is the role of the clamp ring

A

Connects the access door to the wing structure and ensures mounting screw forces are equally distributed on the seals

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25
Q

How is a tank ventilated

A

Air is passed through the tank, which is then released into the atmosphere

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26
Q

What is used to indicate if there has been a leak or not

A

Spur pipe - leak monitor

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27
Q

What are the 2 types of drain valve

A

Direct and indirect drain valves

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28
Q

Which drain valve is installed at the lowest point of a tank

A

Direct drain valve

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29
Q

Where might you find find electrically operated drain valves

A

Stabiliser tanks

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30
Q

What are water scavenge systems used for

A

Remove water that is collected in tanks

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31
Q

Where might you find water scavenge systems installed

A

Big fuel tanks - large quantities of water can be expected

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32
Q

How is ram air used to reduce the tendency for fuel to vaporise

A

Air creates a small positive air pressure on top of the fuel surface

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33
Q

What happens to fuel caught in the vent duct

A

Drained back into the tanks

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34
Q

What is found inside the vent surge tank

A

NACA intake and Overpressure relief valves

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35
Q

Where is the NACA inlet located on the Aircraft

A

Lower wing surface

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36
Q

What are the overpressure relief valves made up of

A

Either carbon discs (break at certain pressure) or Spring loaded valves (open if differential pressure overcomes spring force)

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37
Q

What are the 2 types of refuelling

A

Gravity and Pressure refuelling

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38
Q

What is the main disadvantage of of gravity refuelling

A

Takes a long time

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39
Q

Which tanks do not have external filler ports and how are they refuelled

A

Centre tank and stabiliser tank

Refuelled by transferring fuel from main tanks

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40
Q

What are the two methods of pressure refuelling?

A

Fuel truck (bowser) or underfloor fuel supply system

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41
Q

At what pressure does the fuel get pumped into the the system

A

50 psi

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42
Q

Why is correct distribution of fuel important

A

Danger of CofG shifting behind MLG

Structural stresses

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43
Q

Main components of a refuelling system? (5)

A
  • Coupling
  • Manifold
  • Valves
  • Diffusers
  • Refuelling control panel
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44
Q

What are the three types of refuelling modes

A

Manual
Automatic
Override

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45
Q

What happens when refuelling in manual mode

A

Calculate distribution
Monitor fuel quantities
Operate switches to control refuelling valves

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46
Q

What happens when refuelling in Automatic mode

A

Fuel quantity control computer takes pre-selected block fuel and works out the correct distribution

Controls refuelling valve

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47
Q

When is override mode used

A

No electrical power to refuelling valves available

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48
Q

What is the ‘Normal Mode’ and why is it used

A

Automatic mode

It is safer, reduces workload, stops refuelling when the pre-selected block fuel is reached

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49
Q

Where can control panels be found

A

Wing leading edge near refuelling couplings
On the fuselage
In the cockpit

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50
Q

What can be found to enable the setting of the required block fuel

A

Pre-selector

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51
Q

What are the types of adjuster are there for the pre-selectror

A

Rocker switch, rotary switch or thumb wheel

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52
Q

What are the typical indicators for refuelling

A

Tank quantity indicators
Total quantity indicators
Refuelling valve position indicators (on some)
Malfunction warning lights

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53
Q

When is electrical power usually supplied to the refuelling system

A

When the panel door is open

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54
Q

How is normal refuelling power supplied

A

External power or APU via the fuelling bus

55
Q

What is the fuelling bus also known as

A

Ground handling bus

56
Q

Can power for refuelling come directly from the battery

A

Yes.

57
Q

Where is the fuel distribution calculation stored

A

Fuel control computer

58
Q

Where are refuel couplings generally located if the aircraft only has one

A

Right hand wing

59
Q

Why do couplings incorporate a spring loaded check valve

A

Prevents fuel leaks

60
Q

Durning flight p which tank empties first

A

Centre tank

61
Q

How is damage to the manifold avoided during flight

A

Drain valves at manifold low points in the wing tanks when fuel level is below the manifold

62
Q

Where are the refuelling valves normally attached to

A

Front or rear spars of the wing tank or rear wall of the centre tank

63
Q

Where are the valve control components located

A

Outside the tank

64
Q

How can you open the refuelling valves if there is no electrical power

A

Manual override

65
Q

What are diffusers made of

A

Perforated tube

66
Q

What directs fuel downward once fuel is passed through a diffuser when refuelling

A

A baffle located on the top of the diffuser

67
Q

What are diffusers called on some aircraft

A

Tank distribution manifolds

68
Q

What is the purpose of a fuel feed system

A

Ensures proper fuel supply to engines and APU

69
Q

What are 2 requirements of the fuel feed system if one pump should fail

A

2 boost pumps for every consumer

A bypass of the boost pumps

70
Q

What is the fuel scavenge system used for

A

Reduce the amount of non usable fuel in fuel tanks

71
Q

What is the fuel circulation system used for

A

Fuel is used to cool the integrated drive generator and engine oil system, then passed back to the fuel tank

72
Q

What is the fuel feed system used for

A

Ensures the correct fuel feed sequence

73
Q

How can reverse flow from the fuel feed manifold into the fuel tank occur and how can we prevent this

A

Could happen if one fuel pump is stronger than the other

Check valves prevent this

74
Q

Which valve enables the isolation of fuel flow to an engine

A

Fuel shut off valve

75
Q

How Many cross feed valves does a twin engine aircraft have?

A

1

(NOTE: Other aircraft have more)

76
Q

What is the role of an air release valve

A

Allows air trapped in the fuel line to bleed out under pump pressure

77
Q

How is fuel transfer controlled between the stabiliser tank and the centre tank

A

Transfer valves in the centre tank

78
Q

Where are controls for the fuel feed system found

A

Centre overhead panel

79
Q

What fail safe is there for boost pumps regarding electrical bus bars

A

Power from each pump in the tank comes from a separate bus bar, one boost pump per tank is still available

80
Q

Where are engine fuel shut off valves located on the flight deck

A

Fire panel

81
Q

Where are the most important indications for fuel feed systems located

A

Fuel management control panel

82
Q

What fuel system information can be found on the ECAM page

A

Fuel quantity
Fuel temperature in the tanks
Fuel used since engine start
Total fuel on board

83
Q

How can the fuel shut off valve be activated

A

Engine master switch or respective fire switch

84
Q

What are the two methods of pressure controlled fuel feed

A

High pressure pumps

Sequence valves

85
Q

What fuel tank is used when the aircraft is taxiing

A

Centre tank

86
Q

What tanks are used on take off

A

Respective main tanks

87
Q

What tanks are used first during cruise

A

Centre tanks and stabiliser tank

88
Q

When is fuel transfer permitted during flight

A

Reserve tanks to main tanks in equal amounts, simultaneously

To and from trim tanks

89
Q

What is another method of fuel scavenging

A

Electrically driven scavenge pump

90
Q

How is the issue of adding hot fuel back into tanks resolved

A

Cold fuel is added to the hot fuel to create warm fuel

91
Q

How does the boost pump force the fuel from the inlet to the pump outlet

A

Ac motor drives impeller (centrifugal force)

92
Q

What are the two methods of defuelling an aircraft

A

Pressure defuelling

Suction defuelling

93
Q

What is pressure defuelling and at what pressure is this carried out

A

Defuelling using tank boost pumps, 25-50psi output pressure

94
Q

What is the defuel transfer valve

A

Motor driven pump which interconnects the fuel feed manifold and refuelling manifold

95
Q

What is suction defuelling

A

Use suction from fuel truck to defuel aircraft

96
Q

What is the minimum required suction required for defuelling

A

10-15psi

97
Q

What components do you use during fuel transfer? (5)

A
  • fuel boost pump
  • fuel feed manifold
  • defueling or defuel transfer valve
  • refuelling manifold
  • refuelling valves
98
Q

When may you want to transfer fuel? (2)

A
  • To balance the aircraft after incorrect refuelling

- to empty the tank for maintenance purposes

99
Q

What are trim tank systems used to increase on the aircraft?

A

The efficiency of the aircraft in flight and reduce fuel consumption

100
Q

How could you control the centre of gravity of the aircraft?

A

Transfer fuel fwd or aft

101
Q

What does the fuel control computer do in regards to centre of gravity?

A

Controls the fuel between the trim tank to keep the centre of gravity at the “target centre of gravity”

102
Q

How far forward is the target centre of gravity in relation to limits?

A

2%

103
Q

When will the remaining fuel from the trim tank be transferred forward?

A
  • When the aircraft is below a certain flight level or,

- when approx 75 minutes left until calculated landing

104
Q

Which mode is the trim tank selector switch kept on so that CofG control systems can perform forward and aft fuel movement

A

Auto

105
Q

What does a green forward pointing arrow indicate on the ECAM regarding trim tank indications

A

Normal forward transfer

106
Q

What does an amber arrow indicate on the ECAM regarding trim tank indications

A

Fuel transfer is abnormal

107
Q

When might the valve symbol be shown in amber on the ECAM

A

Valves are open when they have been ordered closed

108
Q

What does the jettison system allow the pilot to do

A

Dump fuel overboard

109
Q

Why might fuel need to be dumped overboard

A

Aircraft exceeds the maximum landing weight

110
Q

What does the design of the jettison system make impossible to do

A

Empty all fuel tanks during flight

111
Q

What is one of the major components of the jettison system

A

Jettison line

112
Q

What is the difference between a fuel boost pump and a jettison pump

A

Jettison pumps have greater flow and pressure capacity which allows them to dump large amounts of fuel quickly

113
Q

What is done with the jettison lines to save weight

A

They are shared with the refuelling manifolds

114
Q

What are the jettison nozzles called and what do they do

A

Anti-corona outlets

They ensure that fuel remains in a non-vaporised compact flow

115
Q

Where is the jettison control panel normally located

A

Overhead panel

116
Q

How is accidental fuel jettison avoided

A

Panel has controls to arm the system and controls to start the jettison

117
Q

Why is it impossible to move the jettison valve switches my accident

A

The switches are guarded

118
Q

How can the jettison operation be interrupted and when can this be done

A

By operating the jettison switch

At any time

119
Q

what unit is fuel on board (FOB) expressed in on the ECAM display

A

Kilograms

120
Q

what unit is total fuel expressed in on the EICAS display

A

Metric Tons

121
Q

How many fuel quantity probes are there in a tank

A

Number of probes depends on size and shape of the tank

122
Q

How are fuel quantity probes installed in a tank

A

Vertically and reach the tank from the bottom of the tank to the top

123
Q

What does a fuel quantity probe consist of

A

2 thin walled aluminium alloy tubes (installed coaxially and electrically isolated from each other, forming a capacitor)

124
Q

What is the material dependant factor called with regards to fuel quantity probes

A

The dielectric constant

125
Q

How does the fuel quantity computer calculate the fuel level

A

Measures the capacitance

126
Q

What do fuel characteristic sensors measure [2]

A
  • Density

- Dielectric constant

127
Q

How many characteristic sensors are located in each tank and what are they

A

2

    - compensator
    - densitometer
128
Q

Why are the fuel characteristic sensors located st the bottom of the fuel tank

A

Ensure they remain covered by fuel for as long as possible

129
Q

What is the accuracy of the fuel quantity calculation

A

Normally greater than 99%

130
Q

What is the fuel level sensing system used for

A

Automatic fuel system control

131
Q

How does a float switch work

A

Contains a reed type switch which has an open circuit when fuel is low, as the fuel level rises a permanent magnet floats up which closes the switch

132
Q

What are the 3 widely used examples of fuel level sensors

A
  • Float switch
  • Thermistor type sensor
  • Single point sensor
133
Q

What is used to measure the fuel temperature in one tank

A

A thermistor

M11 COPY (22 decks)

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