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CAA Module 15 > Module 15.11 Fuel Systems > Flashcards

Module 15.11 Fuel Systems Flashcards

1
Q

Where does the fuel system start?

A

Directly behind the low-pressure fuel shut-off valve.

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2
Q

What does the fuel shut-off valve do?

A

Feeds fuel into the main fuel supply line.

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3
Q

Where does the supply line run?

A

From the wing to the engine accessory gearbox.

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4
Q

What is the dual function of the oil cooler?

A

Cold fuel cools the oil which in turns heats the fuel.

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5
Q

Where does fuel go after exiting the supply line?

A

The low pressure fuel pump.

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6
Q

Where does fuel go after the low pressure fuel pump?

A

To the oil cooler.

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7
Q

What temperature does the oil cooler heat the fuel to?

A

Above the freezing point of water.

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8
Q

What is located after the oil cooler?

A

A fuel filter.

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9
Q

What component is after the fuel filter?

A

High pressure pump

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10
Q

What does the high pressure fuel pump do?

A

Increases the fuel pressure to the level required for correct fuel vaporisation in the engine combustion chamber.

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11
Q

What valve accompanies the high pressure pump?

A

A pressure relief valve.

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12
Q

Where does fuel go to after the high pressure fuel pump?

A

Fuel Control Unit (FCU)

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13
Q

What does the fuel control unit do?

A

Meters the fuel that is needed for combustion.

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14
Q

What two valve does the Fuel Control Unit (FCU) consist of?

A

Fuel Metering Valve

High pressure shut-off valve

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15
Q

What is responsible for the supply and shut-off of fuel to the fuel nozzles at the combustion chamber?

A

The Fuel Control Unit.

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16
Q

Where does fuel go after leaving the Fuel Control Unit?

A

Fuel flow transmitter.

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17
Q

What does the fuel flow transmitter do?

A

Measures the actual fuel flow and transmits signals to the flight deck for the fuel flow and fuel used indication.

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18
Q

After leaving the fuel flow transmitter, where does fuel go?

A

To the engine fuel manifold

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19
Q

What does the engine fuel manifold do?

A

Distributes the fuel to the individual fuel nozzles on the combustion chamber.

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20
Q

What does the low pressure pump increase the fuels pressure to?

A

175 psi

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21
Q

At maximum engine speed, what does the high-pressure fuel pump increase the fuel pressure to?

A

900 psi

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22
Q

What does the high pressure relief valve do and where is it located?

A

Prevents damage to the fuel system components.

Located with the HP fuel pump.

23
Q

Does the high pressure pump supply more of less fuel that is needed for combustion?

A

More

24
Q

What is done to the fuel that’s not needed after the metering stage?

A

It returns to the fuel pump by the bypass return line.

25
Q

What are the two types of engine-driven fuel pump?

A

Constant displacement

Non-constant displacement

26
Q

What is used at the inlet f the engine-driven pump to provide positive flow to the second stage of the pump?

A

A non-constant displacement (centrifugal pump).

27
Q

What lubricated the fuel pump?

A

Fuel passing through the pump

28
Q

Why are heat are heat exchangers needed?

A

To stop water from freezing in the fuel when it reaches 0°C or below in the tank.

29
Q

What two sources of heat can the heat exchangers use?

A

Engine bleed air or engine oil

30
Q

What is an air-to-liquid heat exchanger?

A

A heat exchanger that uses engine bleed air to heat the fuel.

31
Q

What is a liquid-to-liquid heat exchanger?

A

A heat exchanger that uses engine oil to heat the fuel.

32
Q

What type of manifold is found on modern gas turbine engines?

A

Single-fuel manifolds.

33
Q

What are the two types of fuel nozzles?

A

Simplex

Duplex

34
Q

What type of manifold does a duplex fuel nozzle need?

A

Dual manifold

35
Q

What type of manifold does a simplex fuel nozzle need?

A

Single manifold

36
Q

What type of fuel nozzle do modern engines use?

A

SImplex

37
Q

Other than a dual manifold, what else do duplex fuel nozzles need?

A

A pressurising valve or flow divider for dividing primary and secondary (main) fuel flow

38
Q

What are the three engine fuel control system categories?

A

Hydromechanical

Hydromechanical/electronic

Full Authority Digital Engine Control (FADEC)

39
Q

Is the function of fuel control systems?

A

To schedule the fuel flow to match the power requested by the flight crew.

40
Q

What is hydromechanical fuel control system?

A

A system has no electronic interface assisting in computing or metering the fuel flow.

41
Q

What is a hydromechanical/electronic fuel control system?

A

A system where the fuel flow is controlled by the hydromechanical fuel control assembly. An Electronic Engine Control (EEC) adjusts the fuel flow.

42
Q

What is a Full Authority Digital Engine Control (FADEC) system?

A

A system that uses electronic sensors to provide engine parameter information to the EEC.

43
Q

What is the primary component of the FADEC system?

A

The EEC (Electric Engine Controls).

44
Q

What does the EEC (Electric Engine Controls) do?

A

Controls the operation of the engine.

45
Q

What does the EEC housing consist of?

A

Two electronic channels (A and B) that are physically separated.

46
Q

Where is the EEC located?

A

In an area of the nacelle that is cool during engine operation.

47
Q

What supplies the EEC with a signal in proportion to the thrust lever position?

A

The throttle lever angle resolver.

48
Q

What does the cross talk logic in the EEC do?

A

Compares data from channels A and B and uses this to find which EEC channel is the best to control the output driver.

49
Q

What happens if the EEC finds the other (monitoring) channel is better for control of a specific bank?

A

It changes control of that one bank to the other channel.

50
Q

What does the EEC have to store performance and maintenance data?

A

Volatile and non-volatile memory.

51
Q

Where is the Fuel Metering Unit (FMU) is mounted?

A

On the front face of the gearbox and is attached to the front of the fuel pump.

52
Q

What two input connections do both channels of the EEC share?

A

The programming plug and test connectors.

53
Q

What does the programming plug do?

A

Selects the proper software in the EEC for the thrust rating of the engine.

54
Q

When removing the EEC does the programming plug remain with the EEC or the engine?

A

The engine

CAA Module 15 (18 decks)

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