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
2
Q
What is the flash and freezing point of Jet A1 fuel
A
38 degrees C
-47 degrees C
3
Q
Flash and freezing point of Jet A
A
38 degrees C
-40 degrees C
4
Q
Flash and freezing point of Jet B fuel
A
- 20 degrees C
- 58 degrees C
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
6
Q
At a temperature of 15 degrees C what is the density of Jet A1 and Jet A fuel
A
0.81kg/ltr
7
Q
Density of Jet B at 15 degrees C
A
0.78kg/ltr
8
Q
What requirements are their for fuel characteristics? (3)
A
✈️Adequate lubrication
✈️low tendency to hold water
✈️widely available worldwide
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
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
11
Q
What does the fuel storage system consist of
A
Fuel tanks
Tank drain system
Tank vent system
12
Q
Where can fuel tanks be found
A
Wings
Centre fuselage
Horizontal stabilisers
Cargo compartments
13
Q
On which aircraft does there have to be space for reserve fuel
A
All aircraft
14
Q
What are vent surge tanks used for
A
Help make sure fuel tanks are properly vented
15
Q
What purpose do trim tanks serve as well as storing fuel?
A
Used to trim the Aircraft
16
Q
What is the most common type of fuel tank used on modern jet aircraft and why
A
Integral tanks - weight saving
17
Q
How do integral tanks save weight on aircraft
A
Parts of the aircraft structure are used as tank walls
18
Q
How are integral tanks made leak tight
A
Fillet seal where two plates join and cap seals to cover nuts and bolts
19
Q
What type of tank has a light metal alloy outer housing and a flexible rubber bladder
A
Bladder type fuel tank
20
Q
How is fuel movement dampened
A
Ribs in the wing and non sealing divider walls
21
Q
Why does fuel movement need to be dampened
A
Fuel splashing around during attitude changes would make the aircraft unstable
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
23
Q
What provides the metal contact between the access door and aircraft structure?
A
Knit Aluminium Gasket
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
25
How is a tank ventilated
Air is passed through the tank, which is then released into the atmosphere
26
What is used to indicate if there has been a leak or not
Spur pipe - leak monitor
27
What are the 2 types of drain valve
Direct and indirect drain valves
28
Which drain valve is installed at the lowest point of a tank
Direct drain valve
29
Where might you find find electrically operated drain valves
Stabiliser tanks
30
What are water scavenge systems used for
Remove water that is collected in tanks
31
Where might you find water scavenge systems installed
Big fuel tanks - large quantities of water can be expected
32
How is ram air used to reduce the tendency for fuel to vaporise
Air creates a small positive air pressure on top of the fuel surface
33
What happens to fuel caught in the vent duct
Drained back into the tanks
34
What is found inside the vent surge tank
NACA intake and Overpressure relief valves
35
Where is the NACA inlet located on the Aircraft
Lower wing surface
36
What are the overpressure relief valves made up of
Either carbon discs (break at certain pressure) or Spring loaded valves (open if differential pressure overcomes spring force)
37
What are the 2 types of refuelling
Gravity and Pressure refuelling
38
What is the main disadvantage of of gravity refuelling
Takes a long time
39
Which tanks do not have external filler ports and how are they refuelled
Centre tank and stabiliser tank
Refuelled by transferring fuel from main tanks
40
What are the two methods of pressure refuelling?
Fuel truck (bowser) or underfloor fuel supply system
41
At what pressure does the fuel get pumped into the the system
50 psi
42
Why is correct distribution of fuel important
Danger of CofG shifting behind MLG
Structural stresses
43
Main components of a refuelling system? (5)
- Coupling
- Manifold
- Valves
- Diffusers
- Refuelling control panel
44
What are the three types of refuelling modes
Manual
Automatic
Override
45
What happens when refuelling in manual mode
Calculate distribution
Monitor fuel quantities
Operate switches to control refuelling valves
46
What happens when refuelling in Automatic mode
Fuel quantity control computer takes pre-selected block fuel and works out the correct distribution
Controls refuelling valve
47
When is override mode used
No electrical power to refuelling valves available
48
What is the ‘Normal Mode’ and why is it used
Automatic mode
It is safer, reduces workload, stops refuelling when the pre-selected block fuel is reached
49
Where can control panels be found
Wing leading edge near refuelling couplings
On the fuselage
In the cockpit
50
What can be found to enable the setting of the required block fuel
Pre-selector
51
What are the types of adjuster are there for the pre-selectror
Rocker switch, rotary switch or thumb wheel
52
What are the typical indicators for refuelling
Tank quantity indicators
Total quantity indicators
Refuelling valve position indicators (on some)
Malfunction warning lights
53
When is electrical power usually supplied to the refuelling system
When the panel door is open
54
How is normal refuelling power supplied
External power or APU via the fuelling bus
55
What is the fuelling bus also known as
Ground handling bus
56
Can power for refuelling come directly from the battery
Yes.
57
Where is the fuel distribution calculation stored
Fuel control computer
58
Where are refuel couplings generally located if the aircraft only has one
Right hand wing
59
Why do couplings incorporate a spring loaded check valve
Prevents fuel leaks
60
Durning flight p which tank empties first
Centre tank
61
How is damage to the manifold avoided during flight
Drain valves at manifold low points in the wing tanks when fuel level is below the manifold
62
Where are the refuelling valves normally attached to
Front or rear spars of the wing tank or rear wall of the centre tank
63
Where are the valve control components located
Outside the tank
64
How can you open the refuelling valves if there is no electrical power
Manual override
65
What are diffusers made of
Perforated tube
66
What directs fuel downward once fuel is passed through a diffuser when refuelling
A baffle located on the top of the diffuser
67
What are diffusers called on some aircraft
Tank distribution manifolds
68
What is the purpose of a fuel feed system
Ensures proper fuel supply to engines and APU
69
What are 2 requirements of the fuel feed system if one pump should fail
2 boost pumps for every consumer
A bypass of the boost pumps
70
What is the fuel scavenge system used for
Reduce the amount of non usable fuel in fuel tanks
71
What is the fuel circulation system used for
Fuel is used to cool the integrated drive generator and engine oil system, then passed back to the fuel tank
72
What is the fuel feed system used for
Ensures the correct fuel feed sequence
73
How can reverse flow from the fuel feed manifold into the fuel tank occur and how can we prevent this
Could happen if one fuel pump is stronger than the other
Check valves prevent this
74
Which valve enables the isolation of fuel flow to an engine
Fuel shut off valve
75
How Many cross feed valves does a twin engine aircraft have?
1
| (NOTE: Other aircraft have more)
76
What is the role of an air release valve
Allows air trapped in the fuel line to bleed out under pump pressure
77
How is fuel transfer controlled between the stabiliser tank and the centre tank
Transfer valves in the centre tank
78
Where are controls for the fuel feed system found
Centre overhead panel
79
What fail safe is there for boost pumps regarding electrical bus bars
Power from each pump in the tank comes from a separate bus bar, one boost pump per tank is still available
80
Where are engine fuel shut off valves located on the flight deck
Fire panel
81
Where are the most important indications for fuel feed systems located
Fuel management control panel
82
What fuel system information can be found on the ECAM page
Fuel quantity
Fuel temperature in the tanks
Fuel used since engine start
Total fuel on board
83
How can the fuel shut off valve be activated
Engine master switch or respective fire switch
84
What are the two methods of pressure controlled fuel feed
High pressure pumps
| Sequence valves
85
What fuel tank is used when the aircraft is taxiing
Centre tank
86
What tanks are used on take off
Respective main tanks
87
What tanks are used first during cruise
Centre tanks and stabiliser tank
88
When is fuel transfer permitted during flight
Reserve tanks to main tanks in equal amounts, simultaneously
| To and from trim tanks
89
What is another method of fuel scavenging
Electrically driven scavenge pump
90
How is the issue of adding hot fuel back into tanks resolved
Cold fuel is added to the hot fuel to create warm fuel
91
How does the boost pump force the fuel from the inlet to the pump outlet
Ac motor drives impeller (centrifugal force)
92
What are the two methods of defuelling an aircraft
Pressure defuelling
| Suction defuelling
93
What is pressure defuelling and at what pressure is this carried out
Defuelling using tank boost pumps, 25-50psi output pressure
94
What is the defuel transfer valve
Motor driven pump which interconnects the fuel feed manifold and refuelling manifold
95
What is suction defuelling
Use suction from fuel truck to defuel aircraft
96
What is the minimum required suction required for defuelling
10-15psi
97
What components do you use during fuel transfer? (5)
- fuel boost pump
- fuel feed manifold
- defueling or defuel transfer valve
- refuelling manifold
- refuelling valves
98
When may you want to transfer fuel? (2)
- To balance the aircraft after incorrect refuelling
| - to empty the tank for maintenance purposes
99
What are trim tank systems used to increase on the aircraft?
The efficiency of the aircraft in flight and reduce fuel consumption
100
How could you control the centre of gravity of the aircraft?
Transfer fuel fwd or aft
101
What does the fuel control computer do in regards to centre of gravity?
Controls the fuel between the trim tank to keep the centre of gravity at the “target centre of gravity”
102
How far forward is the target centre of gravity in relation to limits?
2%
103
When will the remaining fuel from the trim tank be transferred forward?
- When the aircraft is below a certain flight level or,
| - when approx 75 minutes left until calculated landing
104
Which mode is the trim tank selector switch kept on so that CofG control systems can perform forward and aft fuel movement
Auto
105
What does a green forward pointing arrow indicate on the ECAM regarding trim tank indications
Normal forward transfer
106
What does an amber arrow indicate on the ECAM regarding trim tank indications
Fuel transfer is abnormal
107
When might the valve symbol be shown in amber on the ECAM
Valves are open when they have been ordered closed
108
What does the jettison system allow the pilot to do
Dump fuel overboard
109
Why might fuel need to be dumped overboard
Aircraft exceeds the maximum landing weight
110
What does the design of the jettison system make impossible to do
Empty all fuel tanks during flight
111
What is one of the major components of the jettison system
Jettison line
112
What is the difference between a fuel boost pump and a jettison pump
Jettison pumps have greater flow and pressure capacity which allows them to dump large amounts of fuel quickly
113
What is done with the jettison lines to save weight
They are shared with the refuelling manifolds
114
What are the jettison nozzles called and what do they do
Anti-corona outlets
They ensure that fuel remains in a non-vaporised compact flow
115
Where is the jettison control panel normally located
Overhead panel
116
How is accidental fuel jettison avoided
Panel has controls to arm the system and controls to start the jettison
117
Why is it impossible to move the jettison valve switches my accident
The switches are guarded
118
How can the jettison operation be interrupted and when can this be done
By operating the jettison switch
At any time
119
what unit is fuel on board (FOB) expressed in on the ECAM display
Kilograms
120
what unit is total fuel expressed in on the EICAS display
Metric Tons
121
How many fuel quantity probes are there in a tank
Number of probes depends on size and shape of the tank
122
How are fuel quantity probes installed in a tank
Vertically and reach the tank from the bottom of the tank to the top
123
What does a fuel quantity probe consist of
2 thin walled aluminium alloy tubes (installed coaxially and electrically isolated from each other, forming a capacitor)
124
What is the material dependant factor called with regards to fuel quantity probes
The dielectric constant
125
How does the fuel quantity computer calculate the fuel level
Measures the capacitance
126
What do fuel characteristic sensors measure [2]
- Density
| - Dielectric constant
127
How many characteristic sensors are located in each tank and what are they
2
- compensator
- densitometer
128
Why are the fuel characteristic sensors located st the bottom of the fuel tank
Ensure they remain covered by fuel for as long as possible
129
What is the accuracy of the fuel quantity calculation
Normally greater than 99%
130
What is the fuel level sensing system used for
Automatic fuel system control
131
How does a float switch work
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
What are the 3 widely used examples of fuel level sensors
- Float switch
- Thermistor type sensor
- Single point sensor
133
What is used to measure the fuel temperature in one tank
A thermistor
