Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Module 15 > 15.11 > Flashcards

15.11 Flashcards

(108 cards)

Start Studying
1
Q

The fuel quantity changes with what?

A

Ambient pressure and temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What can happen if the quantity of the fuel is excessive?

A

Rich blow out (turbine temp is exceeded) and stalling.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

When does a rich blow out happen? (2 things)

A

The amount of oxygen in the air supply isn’t good enough.
Or if the mixture is cooled below the temperature for combustion by excessive fuel.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

When must energy/fuel be transferred to the turbine more than necessary?

A

When rapid acceleration occurs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

When does an over rich condition occur?

A

If there is too much fuel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What can an over rich condition cause? (2 things)

A

A rich blow out
Compressor stall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the hydromechanical/electronic fuel control?

A

A hybrid of the two fuel systems

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What does the dual mode in hydromechanical/electronic allow?

A

The inputs and outputs to be electronic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the best affect if the hydromechanical/electronic system fails electronically?

A

It still has mechanical linkages

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What allows the inputs and outputs in a hydromechanical/electronic fuel system to control fuel rate?

A

Servo valves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Even though hydromechanical/electronic uses servo to control the inputs, what does FADEC use fir the same function?

A

Electronic sensors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What do the inputs from the sensor of the computing sections of FADEC rely on?

A

ECC which metres the fuel flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Despite the different types of fuel control systems, what is the overall goal for the fuel systems?

A

To have enough fuel for the power of the engine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the two sections of el control?

A

Metering and computing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What fuel system has no electronic interface?

A

Mechanical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the hydromechanical fuel control system controlled by?

A

The gas generator gear train (Gearbox as its the only thing in the engine that will drive the mechanical pumps)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Disadvantage of hydromechanical fuel control system?

A

It Is less accurate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What directs the fuel flow in a hydromechanical/electronic fuel system?

A

The EEC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Where is the ECC located in the hydromechanical/electronic fuel system?

A

Remote of the engine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

3 functions of the engine fuel systems?

A

To pressurise,
metre fuel flow
Send atomised fuel to the combustion section of the engine (for combustion and cooling)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What provides high pressure fuel to the fuel control system?

A

The vane fuel pump

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What type of pump is the vane fuel pump?

A

Fixed displacement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What does the filter bypass valve allow for in the fuel pump?

A

Fuel to bypass the filter if it’s blocked (Pressure drops)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What two things happen when a blockage occurs?

A

Differential pressure indicator says theres a block
A pin extends from the fuel filter bowl

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
In the electrical aspect of the hydromechanical/electronic fuel system. what does the EEC consist of?
PLA Potentiometre
26
Where is the PLA potentionmetre mounted?
On the aircraft on the throttle quadrant
27
Where are control signals sent to for interpretation?
EFCU (throttle levers will be pushed to a certain position, then this position will be collected to the potentionmetre which is included in the EEC and from here will be sent to the EFCU which receives the control signals to then metre fuel flow because it uses the position of the thorttlke to assume the required fuel)
28
When the EFCU decides a power change is needed (more fuel) what modulates the differential pressure at the head sensor?
Torque motor
29
Where is the EFCU located?
Remotely on the airframe
30
What does the FADEC use to provide information to the EEC?
Electronic sensors
31
What gives commands to the fuel metering valve in FADEC?
EEC
32
What does the fuel metering valve measure?
Fuel flow
33
What fuel systems do turbofan high bypass engines use?
FADEC
34
What is the EEC?
A computer that controls the operation of the engine
35
How many channels does an EEC contain?
2 (A and B)
36
How is the EEC cooled?
By convection
37
Where is the EEC stored?
Engine nacelle
38
What supplies the EEC in FADEC with the proportion of the thrust lever position?
Thrust lever angle resolver
39
What does the crosstalk in EEC'S decide?
Which channel s best to use for control of output
40
Does the EEC have volatile or non volatile memory?
Both
40
What does the primary channel control?
ALL output drivers
41
Where is the FMU mounted?
On the front face of the gearbox attatched to fuel pump
42
What starts/stops fuel?
Shut off valve
43
In a FADEC system what provides feedback?
LVDT, RVDT and thermocouples (mounted on the fuel outlet line of the rear oil cooler and sends information to the EEC)
44
What does the programming plug do?
Selects proper software in the EEC for thrust rating
45
When removing an EEC where does the programming plug stay?
On the engine fan case via a lanyard
46
What 2 subsystems can fuel be split into?
Distribution and control
46
Fuel distrbution has what three tasks?
Pressurise the fuel Supply fuel to combustion chamber Heat the fuel (no ice in nozzles)
47
Where does the fuel system usually start?
Behind LP fuel shut off valve
47
What does the LP fuel shut off valve do?
It feeds the fuel into the fuel main supply line
47
What component comes after the LP fuel shut off valve?
The LP pump
48
What comes after the LP pump?
Oil cooler
49
What is the dual function of the oil cooler? What come after?
Cools the oil and heats the fuel HP fuel pump
50
What occurs in the HP fuel pump? What comes after?
Fuel is pressurised to level required for vapourisation in combustion chamber FCU
51
What 2 things does the fuel control unit do? What comes after?
Metres the fuel needed for combustion Responsible for supply/shut off of fue to fuel nozzles FFT
52
What does the fuel flow transmitter do?
Measures fuel flow and indicates to flight deck
53
What happens after the fuel flow transmitter?
The fuel is directed to the engine fuel manifold
54
What does the engine fuel manifold do?
Distributes to individual nozzles
55
What PSI does the low pressure fuel pump pressurise to?
175 psi
56
What does LP pump distribute to?
Oil cooler, fuel filter and HP pump
57
When is high pressure fuel pump used?
When engine at max speed
58
What PSI is the HP pump pressurising to?
900
59
What does the overpressure relief valve do in the HP compressor?
Prevent damage to fuel systems
60
Fuel from HP pump flows where?
to the metering section of FCU
61
How much does the pump, pump fuel for combustion?
More than enough (incase of rapid acceleration)
62
Un needed fuel goes where?
Back to the fuel pump via the fuel bypass return line
63
What lets only metered fuel enter the nozzles?
The metering section
64
Two types of pressurised pumps?
Constant displacement Non Constant displacement
65
What decides which pump is used?
Where they are in the engine fuel system
65
Where is a non constant displacement (Centrifugal) used?
At the inlet of a pump to provide positive pressure
66
What is the centrifugal pump (non constant displacement) referred to as?
Boost stage pump
67
How are fuel pumps lubricated?
By passing fuel so must never be run dry
68
What psi do the LP pumps increase the system pressure to?
175
69
Where does the LP pump fuel flow to?
The oil cooler and the fuel filter after being pumped through HP pump
70
What psi do the HP pump increase system pressure to?
900psi
71
What does the HP pump have that the LP pump doesnt?
An overpressure relief valve to prevent damage to the systems
72
Where is a LP filter positioned?
In between supply tank and engine fuel system to protect engine driven pumps
73
Where is the HP filter installed?
Between the fuel pump and fuel control unit to protect from any contaminants arising from LP pump.
74
What filter has the greatest filtering action?
Microns
75
Porous cellulose material used in construction of cartridges is can remove what size micron?
10-25
76
What is required for filters with minute openings? (Microns)
Bypass valve (clogging)
77
What mesh filters are most widely used?
200 and 35 mesh microns
78
What are micron filters made up of?
Mesh steel wire
79
What prevents the formation of ice in fuel systems?
Heat exchangers
80
What is the source of heat for heat exchangers?
Bleed air or engine oil
81
How do fuel nozzles ensure that the combustion is done evenly?
It sprays in a highly atomised spray pattern
82
What does the fuel manifold do?
Distribute fuel to the nozzle
82
What does keeping the flame within the liners and in the centre prevent?
Hot spots
83
Where is a single fuel manifold found?
Modern gas turbine engine
83
What does the single fuel manifold surround?
The combustion case
84
Two method of protecting connections from leaks?
Shrouded connections Double sealed connection
84
What is on the fuel lines to catch any fluid leaks? And where are the leaks sent?
Shrouds and they are sent to the drain mast.
85
What do shrouded connections do and don't do?
They don't prevent leaks but they catch and carry them away via the engine drain system
86
What prevents leaks from the coupling connector nut getting onto the combustion case?
O-ring
87
On older aircraft how many lines and manifolds were used?
2
88
Two types of fuel nozzles?
Simplex (Single valve) Duplex (Double manifold and pressurising valve/divider to seperate secondary and primary)
89
Where is a fuel nozzle mounted externally?
Via a mounting pad on the CASE or the INLET AIR ELBOW
90
Where are fuel nozzles mounted internally?
On the Liner dome (remove chamber cover for maintenance)
91
Where is fuel suppled in the combustion chamber?
Forward part
92
What is a disadvantage of simplex fuel nozzles?
Covers a small range as discharge orifice is small. Good for ignition only, not reaching take off power
93
What can you use to cover a good fuel range?
Two sets of simplex nozzles
94
What are primary fuel nozzles used for (In two sets of simplex nozzles)?
Small discharge orifice so start up, to idle
95
What are secondary fuel nozzles used for (In two sets of simplex nozzles)?
Acceleration to maximum power
96
Modern aircraft use duplex nozzles. What are they?
Dual flow nozzles in one
97
What prevents carbon formation?
A check valve in the fuel nozzle
98
When does the check valve close?
When the HP fuel shut off valve is closed (pressure decrease)
99
What does the check valve ensure?
That no fuel flows to the combustion chamber from manifold by gravity.
100
What is the dual function of the oil cooler?
Oil heats the fuel and the fuel cools the oil

Module 15 (18 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions