Fuel System

Question 1

What path does a molecule take from the center tank to the engines?

Answer 1

1. Center tank
2. Transfer ejector
3. Wings
4. Gravity(primary), scavenger ejector(secondary)
5. Collector tank
6. Main ejector or boost pump
7. SOV
8. Filter
9. Engines

Question 2

Scavenger ejectors

Answer 2

2 in each wing and they transfer off the lowest part of the wing to the collector tank

Question 3

How do ejectors move fuel

Answer 3

Motive flow

Question 4

What creates motive flow

Answer 4

Eng. driven fuel pump

Question 5

Transfer ejectors

Answer 5

Moves fuel from center tanks to the wings

Question 6

What send fuel to the collector tanks

Answer 6

Flapper check valves through gravity and through the scavenger ejectors

Question 7

Main ejectors

Answer 7

Sends fuel from the collector tanks to the eng. driven fuel pumps

Question 8

What must happen before the fuel system computer can transfer from center tank to the wing tank?

Answer 8

One engine must be running and fuel in the main tanks below 94%

Question 9

When will boost pumps turn on automatically?

Answer 9

If the main ejectors fail

Question 10

What creates positive pressure in the wing fuel tanks?

Answer 10

NACA scoops and vent lines

Question 11

Why are pressure refueling limits higher than gravity limits?

Answer 11

Fuel cap is lower than highest point in tank

Question 12

What happens when fuel pressure is low with both pumps armed?

Answer 12

Both pumps will come on

Question 13

What tank can’t be fueled using gravity?

Answer 13

Center tank

Question 14

How would you manually cross flow if auto cross flow failed

Answer 14

Low side XFLOW switch

Question 15

Why do you have to be especially careful during manual cross flow?

Answer 15

There are no protections until your imbalance is above 800 lbs

Question 16

What indication would you receive if the Refuel/De-Fuel computer was left on?

Answer 16

“Auto XFLOW inhibit” status

Question 17

How is the fuel kept above 5* C?

Answer 17

Oil/Fuel heat exchanger

Question 18

What is the MLI?

Answer 18

Magnetic level indicator - to manually check fuel loads

Question 19

Why might you see an increase in the center fuel tank after takeoff?

Answer 19

Fuel back flows through the vent lines

Question 20

Where is the bulk temperature fuel probe and readout located?

Answer 20

EICAS right main tank

Question 21

How do you reset FUEL USED value on the FUEL synoptic page

Answer 21

Fuel used reset through the EICAS menu page

Question 22

What would it mean if the powered cross flow pump depiction on the EICAS synoptic page was Amber?
PSM 13-30-3

Answer 22

The pump failed

Question 23

What are the functions of the fuel boost pumps?

PSM 13-40-1

Answer 23

1. Supplies fuel to the engines during start

2. Backup to the main ejectors if they fail

Question 24

What bus is the AZpU fuel pump on?

PSM 13-40-7

Answer 24

Battery bus

Question 25

What prevents overfilling of the fuel tanks?

Answer 25

High level sensors