Fuel System Flashcards

1
Q

Explain the fuel system.

A

Two separate wing fuel systems connected via a cross-feed line and valve.

Each wing consists of a main and an auxiliary system.

The main system holds 386 gallons, the auxiliary holds 158 gallons.

Main - 2,586 pounds
Auxiliary - 1,058 pounds
Total - 544 gallons, 3,644 pounds

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2
Q

How does fuel flow to the nacelle tank?

A

Gravity fed

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3
Q

How is fuel transferred from the auxiliary tank into the nacelle tank to the main fuel system?

A

Via a jet pump

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4
Q

Which fuel is used first? Auxiliary or main?

A

The auxiliary

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5
Q

How many types of fuel pumps are there? What are they?

A

Two - high pressure fuel pump & low pressure boost pump that are engine driven through the accessory drive section

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6
Q

What does the high pressure fuel pump do?

A

Delivers fuel to the engine

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7
Q

What does the engine driven boost pump do?

A

Delivers low pressure fuel into the high pressure fuel pump to prevent cavitation and ensure continuous flow of fuel

Cavitation - air bubbles generated inside of the pump because the partial pressure drop of the flowing liquid, resulting in a cavity at the relevant part. The changes in the pressure turn the liquid into vapor then back to liquid

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8
Q

If the engine driven boost pump fails, which pump should be actuated?

A

The electric standby boost pump

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9
Q

How is the low-pressure standby boost pump powered? Where is it submerged?

A

Electrically, the bottom of the nacelle tank

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10
Q

Explain the routing of the fuel from the tank to the engine.

A

Main tank through the firewall shutoff valve. Through the low pressure engine driven boost pump to the firewall fuel filter and pressure switch through a fuel heater to the engine fuel pump. Then onto the fuel control unit (FCU) and then through the fuel flow transmitter. Through the dual fuel manifold to the fuel sprayer nozzles and into the annular combustion chamber.

Fuel can also be pulled after the firewall fuel filter to supply the auxiliary tank transfer system with motive fuel flow.

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11
Q

While the auxiliary system is in use, how is fuel transferred from the aux tank to the nacelle tank?

A

Via jet transfer pump

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12
Q

When there is auxiliary fuel available, fuel is automatically transferred from the aux tank to the ______ tank.

A

Nacelle

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13
Q

What principle does the jet transfer pump in the auxiliary tank operate on?

A

The Venturi principle - using the fuel and boost pump for motive flow

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14
Q

How does the jet pump draw fuel from the aux tank?

A

The Venturi effect creates suction in the jet pump, which draws the fuel

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15
Q

How long is the time delay built into the automatic transfer system during engine start?

A

30-50 seconds

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16
Q

Why is there a time delay in the automatic transfer system during engine start?

A

To allow all the fuel pressure to be used for engine starting

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17
Q

What should be monitored early in the flight pertaining to the fuel system?

A

The auxiliary fuel level to ensure the transfer of fuel is taking place

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18
Q

What will extinguish the red FUEL PRESS warning light?

A

Fuel pressure supplied by either the engine driven boost pump or the electric standby boost pump (25-30PSI), a minimum of fuel 10+- 1 PSI is required to extinguish the light

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19
Q

What does the motive flow valve do?

A

Allows for fuel to flow through the auxiliary transfer line

20
Q

What would extinguish the amber NO TRANSFER light on the fuel panel?

A

If the auxiliary fuel transfer line has at 4-6 PSI

21
Q

When the auxiliary tank empties and the motive flow valve closes, why does it NOT illuminate the NO TRANSFER light?

A

Because there is no more fuel left to transfer

22
Q

When would the NO TRANSFER light illuminate with fuel in the aux tanks?

A

If the motive flow valve closed or if motive flow pressure was lost in the transfer lines

23
Q

If the motive flow fuel pressure was lost and the NO TRANSFER illuminated, what could you do to extinguish the light?

A

Manually energize the motive flow by placing the auxiliary transfer switch from AUTO to OVERRIDE, which would bypass the automatic feature in the aux transfer system and send DC power directly to the motive flow valve.

On SN BB-32 and subsequent models, OVERRIDE switch does not extinguish the light until the motive flow valve has opened.

On SN BB-2 thru BB-31, selecting to OVERRIDE will extinguish the light but doesn’t guarantee fuel flow. Monitor the aux fuel level to verify its decreasing.

24
Q

What’s the purpose of the firewall shutoff valves?

A

Close off the fuel flow to the engines

25
Q

What are the firewall shutoff valves powered by?

A

The hot battery bus

26
Q

What’s the engine driven boost pump protected from contamination by?

A

A strainer

27
Q

When does the boost pump operate?

A

Anytime the gas generator N1 is turning and provides sufficient fuel to the high-pressure pump for all flight conditions

28
Q

When a low pressure engine driven boost pump fails, the L or R FUEL PRESS light illuminates, how can you extinguish the light?

A

Activation of the standby boost pump

29
Q

How many hours is the operation limited to with the fuel pressure light on?

A

10 hours before overhaul or replacement of the high pressure main engine fuel pump

30
Q

What are the 3 functions of the standby boost pump?

A

Backup pump for use in the event of engine driven boost pump failure

Used with aviation gas above 20,000 feet

Used during crossfeed operation

31
Q

What happens with crossfeed if one standby boost pump fails?

A

Crossfeed can only be accomplished from the side of the operative standby pump

32
Q

Why must during shutdown should the standby pumps and the crossfeed flow switches be in the OFF position?

A

They are controlled by the hot battery bus and if left on they will cause battery discharge

33
Q

When is fuel heated?

A

Prior to entering the fuel control unit by and oil-to-fuel heat exchanger

34
Q

What’s the purpose of heating fuel?

A

To melt any ice formed in the fuel lines

35
Q

What’s the temperature the fuel is heated to?

A

70-90 degrees, if it goes above 90 then it will bypass the fuel heater

36
Q

What’s the purpose of the high pressure engine fuel pump?

A

Supplies the fuel pressure needed for a proper spray pattern in the combustion chamber.

37
Q

What happens if the high pressure engine fuel pump fails?

A

An immediate engine flameout.

38
Q

When is fuel cross feeding conducted?

A

Single engine operation only

39
Q

What’s the purpose of crossfeed?

A

To get fuel from the inoperable engine side to the operative engine side

40
Q

To crossfeed, how should the standby pump switches be placed?

A

To OFF

41
Q

How must the auxiliary transfer switch be positioned during crossfeed?

A

On AUTO to the side being crossfed

42
Q

When placed into crossfeed, what 4 circuits are directly affected? What is one indication that can be indirect?

A

The green FUEL CROSSFEED annunciation illuminates

The crossfeed valve OPENS

Standby boost pump on delivery side will be turned on

Motive flow valve on receiving side will close, stopping aux tank fuel transfer

**If there is fuel in the receiving sides aux tank when crossfeed selected:

NO TRANSFER light on receiving side will illuminate (will not occur if there is no aux fuel available)

43
Q

When fueling, which tanks should be filled first?

A

The mains

44
Q

How often are fuel filters supposed to be cleaned?

A

Every 100 hours

45
Q

What’s the zero fuel weight for the 200/B200?

A

10,400lbs (200), 11,000lbs (B200)

46
Q

Takeoff is prohibited if the fuel gage indicates what amount?

A

265 pounds or less or in the yellow arc

47
Q

How many hours is engine operation limited to with its corresponding L FUEL PRESS or R FUEL PRESS annunciation illuminated?

A

10 hours between overhaul or replacement of the high pressure engine fuel pump