Fuel Flashcards
What is the fuel used for ?
To supply fuel to the engines, APU and IDG for cooling
What is the purpose of keeping fuel in the outer while in flight
For bending moment and flutter relief
What is the fuel expansion at maximum capacity ?
An additional 2% of expansion, which is the equivalent of 20° rise in fuel temperature, wihout spilling over into the vent surge tanks
Where are the vent surge tanks located ?
Outboard of the wing tanks
What is the capacity of the vent surge tank ?
190 kg before overflowing through the NACA air intake.
What happens if fuel spills into the vent surge tank ?
It is brought back into the outer with a scavenge pump
What is the purpose of the vent surge tanks ?
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
How does the fuel ventilation work ?
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.
What is the purpose of the water drain valves ?
They are used to remove either water accumulated in the tanks or for mechanics to drain the remaining fuel
How many water drain valves ?
8 in total (1 in each outer - inner and vent surge tanks, 2 in center tank)
What is the maximum capacity of the outer tank ?
691 kg (for CEO)
What is the maximum capacity of the inner tank ?
5435 kg (CEO)
What is the maximum capacity of the center tank ?
6476 kg (for CEO)
What is the maximum capacity of all the tanks ?
18 729 kg (for CEO)
On older A320 how many centrifugal booster fuel pumps are there ?
6 pumps (2 in the center and 2 in each inner tanks)
On newer A320, how many fuel pumps are there ?
4 main fuel pumps (2 in each inner tank) and 2 jet pumps in the center tank
How many intertank transfer valves are there ?
2 electrical valves to permit transfer from outer to inner tank
What is the purpose of the suction valves ?
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.
What is the particularity with gravity feeding and older A320 fitted with old centrifugal boost pump ?
Center tank is not fitted with suction valves, therefore gravity feeding is not possible from the center tank.
What is the difference between old centrifugal boost pump and newer jet pumps ?
What is the normal fuel feed sequence ?
- 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
What is the logic of the center tank valves ?
Each center pump stops until 500kg of the fuel of the associated inner tank has been used.
What is the logic of the fuel transfer from outer to inner ?
The transfer valves (2 valves) will automatically open when inner tank fuel reaches 750kg.
What is the logic of the transfer from center to inner (newer jet pumps)
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
Where does the APU fuel taken from ?
Normally from left fuel lines (or right if crossfeed is open)
What is the purpose of the fuel recirculation system ?
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
How much time to refuel an aircraft ?
17 min for wing tanks or 20 min for all the tanks
What is the logic of the center boost pumps in AUTO mode ?
- 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
What is the logic of the center jet pumps in AUTO mode ?
- Pumps open if the associated inner tank is not full
- Pumps stop 5 minutes after center tank low level is reached
When does an advisory appear for the fuel temperature ?
When T° is :
- above 45°C for the inner cell, or 55°C for the outer cell
- below -40°C
When does an advisory appear for the fuel discrepancy ?
When the fuel quantity in two wings is greater than 1500kg
What is the tolerance on fuel on board values ?
+/- (1% of the current FOB + 1% of the max possible FOB)
In case of FQI degradation, what is the loss of accuracy in the tanks ?
Wings outer affected : +20 ; -200kg
Wings inner affected : +/- 110kg
Center tank affected : +/- 130kg
All tanks affected : +390 ; -750kg
