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Call of the Heavies > Fuel System > Flashcards

Fuel System Flashcards

1
Q

How many fuel tanks? (not including the surge tanks)

A

7

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2
Q

Name all the fuel tanks

A

-Center wing tank
-Main tanks (1, 2, 3, 4)
- Reserve tanks (Called reserve 2 and reserve 3)

(Also there is a surge tank at the very end of the wingtips, but no control or indication of it)

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3
Q

Does each tank have a fuel quantity sensor?

A

Yes (except for surge tanks)

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4
Q

Where is fuel temperature measured?

A

Main tank 1

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5
Q

In general, what is an FSMC?

A

Fuel system management card

These command fuel valves open or closed and pumps on or off. Some of these commands occur automatically and some depend on panel switches

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6
Q

What is a surge tank? How many?

A

One surge tank per wing, furthest outboard portion of the wing. Provide of relieving fuel surge in other tanks and for venting as fuel is consumed.

NO CONTROL OR INDICATION OF SURGE TANKS

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7
Q

Is fuel transfer a possibility?

A

Yes

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8
Q

Why are the reserve tanks titled “reserve tank 2” and “reserve tank 3”?

A

Because they feed into main tank 2 or main tank 3.

Reserve tank 2 feeds into main 2
Reserve tank 3 feeds into main 3

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9
Q

So reserve tank 2 and reserve tank 3 feed into main tank 2 and 3. Is this automatic?

A

Yes. When the respective main tank drops to 18,200 KG, the transfer valves open up and allow flow from the respective reserve tank into the respective main tank.

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10
Q

When the fuel quantity of either main 2 or main 3 drops below ______KG, the transfer valves open and gravity feed from reserve 2 or 3 into main 2 or 3. When does this process stop?

A

18,200 KG

It goes until all of the fuel is depleted out of the reserve tanks

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11
Q

Each main fuel pump has the capacity to operate how many engines?

A

1 engine at takeoff thrust

2 engines at cruise thrust

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12
Q

How many main pumps are in each main fuel tank?

A

2 main AC fuel pumps per each main tank

Forward and aft

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13
Q

In addition to having 2 main pumps, what fuel pumps are in main tank 2 and 3?

A

A forward and an aft override/jettison pump in main tank 2 and main tank 3.

Also a DC fuel pump in tank 2

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14
Q

Is an override/jettison pump more powerful than a main pump?

A

Yes. It can supply fuel to 2 engines at takeoff thrust or cruise thrust.

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15
Q

Override/jettison pumps in tanks 2 and 3 can operate until the quantity is decreased to the standpipe level of about _____KG.

A

3,200 KG

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16
Q

The left and right pumps in the center wing tank are what type pumps?

A

Override/jettison

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17
Q

With both center wing tank override/jettison pumps running, these override the pressure of________.

A

All other pumps

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18
Q

What is inhibited when center wing tank override/jettison pumps are operating?

A

Override jettison pumps in tanks 2 and 3 are inhibited.

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19
Q

How is the center tank designed to be used?

A

The center wing tank fuel is designed to be consumed prior to consumption of fuel from the main tanks.

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20
Q

Can the engines run if the main pumps have low fuel pressure?

A

Yes. They can suction feed and the suction feed lines bypass the fuel pumps

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21
Q

What is the pipe called that connects all main tanks and the center wing tank?

A

The crossfeed manifold

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22
Q

How many crossfeed valves are installed?

A

4

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23
Q

From a functional standpoint, looking at the overhead, what is the difference between pushing a main fuel pump switch versus an override/jettison switch?

A

The Main pumps are manually activated by the switch ON position and the override/jettison pumps are controlled by a combination of the switch ON position and the system logic.

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24
Q

For any fuel pump switch, when would the amber word “PRESS” be illuminated on the switch?

A

MAIN pumps: If PRESS appears, it means the pump is off, or the switch is on but the pump output pressure is low.

Override/Jettison: If PRESS (will appear white) appears, it means the pump is selected ON and the pump output pressure is low. There is no light if the pump is off.

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25
Q

What does the FUEL XFER MAIN 1 & 4 switch do?

A

Not normally operated in flight. But it opens the transfer valves in main tanks 1 and 4, allowing fuel to gravity transfer from outboard mains to inboard mains (Done automatically in-flight during fuel jettison when either tank 2 or 3 gets below 9,072KG).

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26
Q

In flight, would fuel ever automatically transfer from the outboard main tanks to inboard main tanks?

(1 to 2 / 4 to 3)

A

Yes only during fuel jettison.

AND only if either inboard main tank decreases to 9,072 kg

27
Q

Where does the APU normally get its fuel from?

A

Main tank 2 (can take it from main tank 3 if AC pump 2 aft fails).

28
Q

What pumps run when AC power is available to supply the APU with fuel?

A

Main pump 2 aft, and main pump 3 aft.

It draws from main pump 2 aft. But main pump 3 aft arms as well to prevent tank to tank transfer and to be a backup pump.

29
Q

Where is the DC fuel pump? What is it used for?

A

Main tank 2. Used for APU start

30
Q

When should the center wing tank fuel pumps ( L CTR R) be on?

A

Whenever the center wing tank has over 7,700 KGs of fuel

31
Q

Why should you burn fuel from the CWT first and then the mains?

A

Because all of the lift is produced by the wings. In flight, the heavier the fuselage is, the more stress it puts on the wing spars. If you reduce that weight first, then the wings are not stressed for as long. It extends the life of the wing spars. (In some cases you may even be limited to how much fuel you can put in the CWT for airframe stress limits)

32
Q

After you burned all the fuel from the CWT and deactivate the CWT pumps, what pumps activate and how is fuel supplied?

A

Override/jettison pumps 2 and 3 activate.

Override/jettison pump 2 provides pressure for engine 1

Override/jettison pump 3 provides pressure for engine 4

Main pumps 2 and 3 provide fuel to their associated engine

33
Q

How many scavenge pumps? Where are they What are they for?

A

There are 4 of them. All in the CWT (2 on the left 2 on the right.) They collect any fuel remaining in the CWT and push it into main tanks 2 and 3.

34
Q

When do the scavenge pumps suck fuel from the CWT and dump it into main tanks 2 and 3?

A

Whenever main tank 2 or 3 fuel quantity gets below 27,200 KGs

35
Q

What does the FUEL TO REMAIN switch do?

A

Selects how much fuel you want to remain after jettison.

36
Q

On the fuel jettison panel, what does the FUEL JETTISON switch labeled OFF, A, and B do?

A

OFF: Disarms jettison system and removes EICAS fuel to remain indication
A or B: Arms selected jettison system. Causes EICAS fuel to remain to display.

37
Q

On the fuel jettison panel, what do the L-NOZZLE-R switches do? (2 of them)

A

ON: Jettison nozzle valve selected open. When system armed, it activates override/jettison pumps in tanks containing fuel.
OFF: Jettison nozzle valve selected closed

38
Q

You see an amber VALVE illuminated on one of the L-NOZZLE-R switches. What does this mean?

A

Valve not in selected position

39
Q

Fuel capacity for main 1 and 4

A

26,576 kg

40
Q

Fuel capacity main 2 and 3

A

76,263 kg

41
Q

Fuel capacity center tank

A

52,167 kg

42
Q

Reserve fuel capacity

A

8,036 kg

43
Q

Total fuel capacity

A

163,042 kg

44
Q

On the EICAS, fuel temperature is normally white. What does it mean if you see fuel temperature in amber?

A

Fuel temperature is -37ºC or below.

45
Q

When you activate the jettison system, it displays a to remain indication on EICAS. This replaces the _____ indication.

A

Fuel temperature

46
Q

Does the primary EICAS display fuel quantity?

A

Yes, just TOTAL fuel.

Specific tank fuel is on the synoptic

47
Q

On the fuel synoptic, there are 4 colors that a fuel pump could be. White, green, amber, and cyan. What do these mean?

A

White: Off
Green: On
Amber: Low pressure
Cyan: Armed for system logic (override pumps only)

48
Q

On the fuel synoptic, fuel quantity for each tank has 2 possible colors. White or amber. What do these mean?

A

White: Normal

Amber: Fuel imbalance OR fuel quantity less than 900 kg

49
Q

On the overhead MX panel, there is a switch called DEFUEL RSV 2&3 XFER. What does this do?

A

The reserve tanks have no pumps in them, only transfer valves (2 in each reserve tank) that allow flow from the reserve tanks to the inboard mains (2 and 3). This switch is for defueling and not used by the flight crew.

50
Q

When should you turn the center wing tank pumps on?

A

If the center wing tank has 7,700 kg or more

51
Q

What happens when center wing tank pumps are on, you are on the ground, the center wing tank has above 7,700 kgs, and you extend the flaps?

A

The fuel crossfeed valves 2 and 3 close.

52
Q

For takeoff with center wing tank greater than 7,700 kgs, what engines are being fed off of what tanks and pumps?

A

Engines 2 and 3: Being fed off of their respective tanks by their respective MAIN pumps

Engines 1 and 4: Being fed off of center wing tank by the center wing tank pumps.

53
Q

For a takeoff with the center wing tank being greater than 7,700 kgs, at what point after takeoff does the system change to having all 4 engines feed off of the main tank?

A

When the flaps are out of the takeoff position (10 or 20).

Crossfeed valves 2 and 3 open and the center tank feeds all 4 engines from the center tank pumps

54
Q

At what point does the center wing tank quantity get low enough to generate an EICAS message FUEL LOW CTR?

A

2,300 kgs quantity. Fuel flow is at least 6,800 kgs an hour. You get about 900 more kgs to go before that EICAS message.

55
Q

You see the EICAS message >FUEL LOW CTR L, R and the center pump switches are illuminated an amber PRESS. What is causing this? What should you do?

A

Normal operation. Just telling you its time to stop burning off of the center tank. Simply turn the center pumps off. Message goes away.

56
Q

Once you shut off the center wing tank pumps, how is fuel supplied to the engines?

A

Engines 1 and 2: From override/jettison pump 2

Engines 3 and 4: override/jettison pump 3

57
Q

How does leftover fuel from the center tank get into the main tanks 2 and 3? When does this begin?

A

4 jet pumps in the center tank transfer unused fuel from the center tank to tanks 2 and 3.

These jet pumps activate when main tank quantity gets to 27,200 kg

58
Q

When do the reserve tanks gravity feed the inboard mains?

A

When the inboard mains reach 18,200 kgs.

59
Q

What causes EICAS >FUEL TANK/ENG ?

A

When tank 2 is equal or less than tank 1.
OR
When tank 3 is less than tank 4.

60
Q

Describe the fuel configuration when taking off with CWT less than 7,700 kgs.

A

-Center tank pumps off
-Crossfeed valves 2 and 3 closed when flaps extended
-Override/jettison pumps 2 and 3 provide fuel to engines 1 and 4
-Main pumps 2 and 3 provide fuel to their respective engines.

61
Q

After takeoff with the CWT pumps off, how does the fuel system configure itself after flaps are retracted?

A

-Crossfeed valves 2 and 3 open
-Fuel for engines 1 and 2 supplied from override/jettison pump 2
-Fuel for engines 3 and 4 supplied from override/jettison pump 3.

62
Q

Once reaching cruise, you see the EICAS message: >FUEL OVRD CTR L, R. What does this mean? How do you configure the fuel system?

A

It means you didn’t take off using CWT fuel and there is more than 1,800 kgs still in there, so use it.

Select the center pumps on.

63
Q

Override/ Jettison pumps are how much more powerful than main AC pumps

A

2x

Call of the Heavies (39 decks)

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