28 Fuel Flashcards
What is the fuel feed sequence of a traditional A320?
Centre tanks for 2 mins or until slats extended
Inner tanks until 500kg used
CT until empty (may turn off if recirc fuel puts it up above 500kg limit)
Inner tanks to 750kg
Outer tanks to inner tanks
How is Centre Tank fuel prioritised in the traditional A320 system
CT fuel pumps deliver fuel at higher pressure than inner tanks. As a result the CT pumps drain fuel before the inner tanks
Describe the fuel feed sequence on newer A320’s.
Centre tank first unless the inner is full. 250kgs used from inner before centre tanks TFR’s open. The centre till empty.
If the inner tanks fuel then the jet pump switches off and the valves close. The process is repeated until CT is empty.
Inner tank empties down to 750kg
Outer tank fuel transfers into inner tank
(A321NEO has no outer tank)
Describe fuel recirculating system
Fuel from HP fuel line is diverted through the heat exchanger of the IDG. Heat from the oil is radiated away by the fuel in the exchanger.
It is then sent either to the HP fuel line or sent back to the outer tanks
Why is CT fuel prohibited for TO?
Wing tanks fill before CTs. If fed from CT during TO then recirculated fuel would go into full wing tanks and cause the surge vent to spill excess overboard
What happens to the fuel from the fuel return valve (used for IDG cooling) if the inner tank is already full?
If the FUEL MODE SEL pb is in AUTO, and the centre tank pumps are feeding, the system selects CTR TK PUMPs off, and wing tanks pumps will automatically feed each engine until around 500kg has been used in each wing.
If the FUEL MODE SEL pb is in MAN, the CTR TK PUMPs will not be automatically switched off, which could lead to over flow of the wing tanks.
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Where is the vent surge fuel tank located?
Outboard of the outer tank in each wing
When the fuel is filled to maximum capacity, how much can the fuel expand by without spilling?
2%
What is the total usable fuel on the A320 family approx?
Between 18.5 and 19 tonnes
How many fuel pumps are there on newer A320s and the A321?
Four (two in each wing), the centre “pumps” are jet pumps with transfer valves
How many fuel pumps are there on A319 and older A320 aircraft?
Six (two in each wing, and two in centre tank)
How many transfer valves are located in each wing?
Two
Which electrical system supplies the APU fuel pump if the fuel feed pressure is low (due to loss of tank pumps or normal AC supply)?
The AC ESS SHED
If this fails, it runs off the AC STAT INV BUS
What does the fuel system cool?
The Integrated Drive Generator
The fuel passes through the IDG heat exchanger (which absorbs heat), then to the fuel return valve and back to the outer fuel tank.
This ensure IDG cooling when oil temperature is high or at low engine power.
What happens to the fuel from the fuel return valve (used for IDG cooling) if the outer tank is already full?
The fuel overflows to the inner tank through a spill pipe
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