Fuel

Question 1

What is the fuel used for ?

Answer 1

To supply fuel to the engines, APU and IDG for cooling

Question 2

What is the purpose of keeping fuel in the outer while in flight

Answer 2

For bending moment and flutter relief

Question 3

What is the fuel expansion at maximum capacity ?

Answer 3

An additional 2% of expansion, which is the equivalent of 20° rise in fuel temperature, wihout spilling over into the vent surge tanks

Question 4

Where are the vent surge tanks located ?

Answer 4

Outboard of the wing tanks

Question 5

What is the capacity of the vent surge tank ?

Answer 5

190 kg before overflowing through the NACA air intake.

Question 6

What happens if fuel spills into the vent surge tank ?

Answer 6

It is brought back into the outer with a scavenge pump

Question 7

What is the purpose of the vent surge tanks ?

Answer 7

To receive the fuel from the outer in case of fuel expansion/overspilling and also to ventilate the wing and center tanks using the vent lines, connected to individual tanks

Question 8

How does the fuel ventilation work ?

Answer 8

Vent surge tanks are connected to NACA air intake, which allows ambient air to :

• enter the fuel tank when fuel is being used, or
• exit the fuel tanks when the aircraft is being refueled.

Question 9

What is the purpose of the water drain valves ?

Answer 9

They are used to remove either water accumulated in the tanks or for mechanics to drain the remaining fuel

Question 10

How many water drain valves ?

Answer 10

8 in total (1 in each outer - inner and vent surge tanks, 2 in center tank)

Question 11

What is the maximum capacity of the outer tank ?

Answer 11

691 kg (for CEO)

Question 12

What is the maximum capacity of the inner tank ?

Answer 12

5435 kg (CEO)

Question 13

What is the maximum capacity of the center tank ?

Answer 13

6476 kg (for CEO)

Question 14

What is the maximum capacity of all the tanks ?

Answer 14

18 729 kg (for CEO)

Question 15

On older A320 how many centrifugal booster fuel pumps are there ?

Answer 15

6 pumps (2 in the center and 2 in each inner tanks)

Question 16

On newer A320, how many fuel pumps are there ?

Answer 16

4 main fuel pumps (2 in each inner tank) and 2 jet pumps in the center tank

Question 17

How many intertank transfer valves are there ?

Answer 17

2 electrical valves to permit transfer from outer to inner tank

Question 18

What is the purpose of the suction valves ?

Answer 18

They allow engines to be fed by gravity if the inner tank pump fail. The suction valves are closed and not operating during normal operation.

Question 19

What is the particularity with gravity feeding and older A320 fitted with old centrifugal boost pump ?

Answer 19

Center tank is not fitted with suction valves, therefore gravity feeding is not possible from the center tank.

Question 20

What is the difference between old centrifugal boost pump and newer jet pumps ?

Question 21

What is the normal fuel feed sequence ?

Answer 21

• Additional Center Tank - ACT 2 (if installed)
• Additional Center Tank - ACT 1 (if installed)
• Center tank
• Inner tanks, each inner empties down to 750kg
• Outer tanks, fuel transfer to inner tank

Question 22

What is the logic of the center tank valves ?

Answer 22

Each center pump stops until 500kg of the fuel of the associated inner tank has been used.

Question 23

What is the logic of the fuel transfer from outer to inner ?

Answer 23

The transfer valves (2 valves) will automatically open when inner tank fuel reaches 750kg.

Question 24

What is the logic of the transfer from center to inner (newer jet pumps)

Answer 24

When the transfer valve is open, fuel from the inner tank pumps flow through a jet pump and creates a suction in it. This suction moves the fuel from the center tank to the related inner tank

Question 25

Where does the APU fuel taken from ?

Answer 25

Normally from left fuel lines (or right if crossfeed is open)

Question 26

What is the purpose of the fuel recirculation system ?

Answer 26

Some of the fuel supplied to the engine goes through the IDG heat exchanger (where it absorbs heat), back to the fuel return valve and the outer tank.
It enables the fuel to be heat up by the hot IDG oil temperature and to cool down the IDG oil by the cold fuel

Question 27

How much time to refuel an aircraft ?

Answer 27

17 min for wing tanks or 20 min for all the tanks

Question 28

What is the logic of the center boost pumps in AUTO mode ?

Answer 28

• Pumps run at engine start for 2 minutes
• Before or after enfine start, the pumps run of slats are retracted
• Pumps stop 5 minutes after center tank low level is reached

Question 29

What is the logic of the center jet pumps in AUTO mode ?

Answer 29

• Pumps open if the associated inner tank is not full
• Pumps stop 5 minutes after center tank low level is reached

Question 30

When does an advisory appear for the fuel temperature ?

Answer 30

When T° is :
- above 45°C for the inner cell, or 55°C for the outer cell
- below -40°C

Question 31

When does an advisory appear for the fuel discrepancy ?

Answer 31

When the fuel quantity in two wings is greater than 1500kg

Question 32

What is the tolerance on fuel on board values ?

Answer 32

+/- (1% of the current FOB + 1% of the max possible FOB)

Question 33

In case of FQI degradation, what is the loss of accuracy in the tanks ?

Answer 33

Wings outer affected : +20 ; -200kg
Wings inner affected : +/- 110kg
Center tank affected : +/- 130kg
All tanks affected : +390 ; -750kg