Fuel

Question 1

Will you get a center pressure low lights if the center pumps are turned off?

Answer 1

No they are inhibited.

Question 2

How many fuel pumps are in each fuel tank?

Answer 2

2

Question 3

Are the fuel pumps ac or dc?

Answer 3

Ac

Question 4

Where does the apu get fuel from?

Answer 4

Left fuel feed system

Question 5

What pump provides fuel for apu when ac power is not available?

Answer 5

Dc fuel pump in the left main tank

Question 6

Where do fuel from the surge tanks drain into?

Answer 6

Center tank

Question 7

Where are surge tanks located?

Answer 7

Each wing tip

Question 8

When do you get a fuel config light?

Answer 8

1. A fuel unbalance of 2000 LBS ± 500 between main tanks (EICAS Advi-sory message - FUEL CONFIG).
2. Low fuel quantity less than 2200 LBS in either main fuel tank (EICAS Caution message - LOW FUEL).
3. Center fuel pump switches are off with greater than 1200 lbs in the cen-ter tank (EICAS Advisory message - FUEL CONFIG)

Question 9

Name approximate fuel quantities?

Answer 9

Main tanks each - 40000
Center tank - 80000

Total 160000

Question 10

When does the associated fuel pressure light come on?

Answer 10

When the fuel pump pressure is low.

Question 11

What does the L or R FUEL SYS PRESS message mean?

Answer 11

EICAS caution messages, L or R FUEL SYS PRESS, indicate low fuel pressure in the left or right fuel manifold.

Question 12

Are the center tank pumps more powerful than the main tank pumps?

Answer 12

Yes

Question 13

Why does the aircraft drain the center tanks first?

Answer 13

Because the center fuel pumps are more powerful than the main tank pumps.

Question 14

When is the center tank pumps inhibited?

Answer 14

To reduce electrical loads, the center tank pumps are inhibited in flight or on the ground when the associated N2 is less than 50% RPM. Thus both center tank pumps are inhibited with the engines shutdown.

Question 15

What happens to the center tank pump inhibit when the fueling door is opened?

Answer 15

The inhibit is cancelled

Question 16

Where does the scavenge ejectors transfer fuel to?

Answer 16

From center tanks to each main tank

Question 17

Other than on apu start, when does the dc fuel pump run?

Answer 17

In addition, the pump operates automatically in-flight to provide fuel to the left engine when left engine N2 RPM drops below a preset value, the APU Switch is OFF, and left engine fuel manifold pressure is low. When N2 RPM increases above a preset value, the DC pump shuts down.

Question 18

Can the engines suction feed fuel?

Answer 18

When main tank fuel pump pressure is low, each engine can draw fuel from its corresponding main tank through a suction feed line that bypasses the pump

Question 19

After apu is turned on and running, which fuel pump takes over?

Answer 19

The left fwd fuel pump takes over regardless of switch position

Question 20

Can the left fwd fuel pump be turned off on the ground while the apu is running?

Answer 20

No

Question 21

Can the left fwd fuel pump be turned off in the air while the apu is running?

Answer 21

Yes

Question 22

What happens to the apu if you turn off the left fwd fuel pump in flight?

Answer 22

The apu keeps running as any operating ac fuel pump in the left system can supply fuel to it. If you turn the left fwd pump off, the left aft is still working so the apu keeps running.

Question 23

How does the fueling station normally get power?

Answer 23

Thru the ground handling bus.

Question 24

How does the fueling station get power if the ground handling bus is not available?

Answer 24

Thru the switch for the hot battery bus.

Question 25

How does the tank overfill system work?

Answer 25

If the surge tanks sense any fuel in it, the system shuts off all the fueling valves.