28 - Fuel Flashcards
What is the primary function of the Integrated Drive Generator (IDG) cooling system?
To cool the IDG using fuel from the wing tanks
Which component in the fuel system ensures fuel cannot enter the vent surge tank via the pump if the wing tank pumps are off?
Check valve
What triggers the intercell transfer valves to open between Outer and Inners?
Fuel quantity in the Inner cell below 750 kg.
The valve stays open until the next refuel takes place.
Which component is responsible for gravity feeding fuel to the engines if the wing tank pumps fail?
Bypass Suction Valve is installed on the engine feed line, downstream
of the main pumps. Fuel is sucked from the wing tank by the engine fuel pump thus engine supply is done by “gravity”.
Where are the water drain valves located in the fuel system?
In each wing tank and the centre tank
What is the purpose of the fuel crossfeed valve?
To allow fuel to be fed from one wing tank to both engines
Which component in the fuel system prevents overpressure in the wing tanks?
Pressure relief valve
What is the function of the vent surge tank?
To collect fuel overflow and vent it safely
What is the purpose of the outer fuel cell in the wing?
To have less structural load on the wings, the
fuel in the outer cells is not used until the fuel load in the inner cells
decreases to a low level.
How is an engine isolated from the fuel system in the event of a fire?
Releasing the fire handle shuts the LP fuel valve. This is also true for the APU.
What is the A320 fuel emptying order/logic?
Centre tanks,
Inners
Outers
What is the A320 fuel emptying order/logic?
Wings only, Centres feed to wings with no direct link to engines.
(wing isn’t seperated into inner/outers)
How is fuel in the surge tanks reintroduced back to the outers?
Fuel spilled through the vent pipes into the surge tank is induced by the wing fuel pumps through the scavenge jets back into the outers.
What can you do if an electrical failure of the refuelling valve occurs during fuelling?
Each of the three refuel valves
has a manual plunger, that when pushed that holds the valve open.
How does the centre tank vent?
The centre tank vents into the LH vent surge tank. However, in case of overfuelling of the centre tank most of the fuel flows over to the right wing tank through the relief valve.
What item helps maintain fuel flow to the fuel pumps in any given tank?
Scavenge jet pumps.
Where are the fuel pumps housed in the wings to make sure they are always sufficiently covered in fuel?
Collector tanks.
The wing pumps are ran at 5PSI lower than centre pumps. How is this achieved?
Sequence valves.
The defuel switch only operates on the ground. But what needs to be manually opened during a defuel?
X-feed selected to open
How is recirculated IDG coolant fuel kept below boiling
Px holding valve, bleeds fuel back into the outer tank above 15.5PSI
Due to the IDG recirc function the wing tanks could overfill, how is the ovecome?
The INNER wing cell stops the CTR pump when FULL lvl sensor is wet. Supplies the eng with about 500kg of fuel until UNDERFULL snsr is dry, where CTR pumps will start again.
What is the FLSCU?
Fuel Lvl sensing Control Unit
-Responsible for FQI (Fuel Quantity Indication)
-Fuel tx control
-Fuel management
What happens to Centre Pumps on Eng start?
Run for 2mins regardless of slat position.
In take/off and landing the centre pumps stop, when Slats are extended.
The centre tank has run dry and the pump has sensed low level. What happens?
The centre pumps are on a 5min time delay, so run on after a Lo Px signal.
What happens when you push the APU Fuel Vent P/Bsw?
The APU fuel pump and LP fuel valve will operate to bleed the line.
If the APU was running without engines and you select a L/H wing pump, what would happen?
APU fuel pump Px switch would stop the pump as
crossfeed line Px sensed above 23.3 PSI absolute
