Fuel System Flashcards
What is the purpose of the fuel in the outer tanks?
To relieve wing bending and flutter
By how much can the expand when the aircraft has been refuelled to maximum capacity, without spilling?
By 2%
20°C temperature rise
Where are the overpressure protectors located?
In:
Each vent,
Each outer and inner tank, and
Between the center tank and left inner tank
What is the capacity of the inner tanks?
5435 kg x 2 = 10 870 kg
useable fuel
What is the capacity of the outer tanks?
691 kg x 2 = 1382 kg
useable fuel
What is the total capacity of the wing tanks?
12 252 kg
What is the capacity of the centre tank?
6476 kg of useable fuel
What is the total fuel capacity with all tanks full?
18 728 kg
In normal operation, each engine is supplied by which fuel pumps?
One pump in the Centre tank, or
2 pumps in its own side Inner wing tank
What is the purpose of the two electric transfer valves?
To permit fuel transfer from Outer to Inner tank
How can the engine fuel flow be stopped?
By closing the LP fuel valve via:
- Engine Master switch, or
- ENG FIRE PUSH pb
What is the purpose of the suction valves?
They allow engines to be fed by gravity if the Inner tank pumps fail
What is the position of the suction pumps in normal operation?
Closed
Which fuel pumps are fitted with suction valves?
Inner fuel tank pumps only.
Is gravity feeding possible from the Centre tank?
No, the centre tank fuel pumps are not fitted with suction valves
In what sequence do the fuel tanks empty?
- Centre Tank
- Each Inner Tank empties down to 750kg
- Outer tank fuel transfers to Inner tank
When do the Centre tank fuel pumps stop?
Until ~500kg of fuel in the associated Inner tank has been used
(when the fuel level reaches the underfull sensors)
Will the Centre tank pumps run with the MODE SEL in the MAN position?
Yes
When do the transfer valves automatically open and latch in the open position?
When the inner tank fuel reaches the low level (about 750kg)
When will the transfer valves automatically close?
At the next refuelling
How many fuel level sensors are installed in each Inner tank?
2
What does each level sensor in the Inner tank control?
2 transfer valves - 1 in each wing
ensuring simultaneous transfer to both wings
What is the 750kg (low level) (where transfer valves automatically open allowing the fuel to drain from the outer tank to the inner tank) value based on?
Level aircraft attitude, with no acceleration.
During steep descent or accelerations/decel, the transfer valves may open with >750kg of fuel in each inner tank and the low level warning may be triggered
When does the APU fuel pump operate?
For APU startup
when fuel feed pressure is low
(due loss of tank pumps or loss of normal AC electrical supply)
What bus does the APU fuel pump normally run off?
AC ESS SHED
runs off the AC STAT INV BUS if the AC ESS SHED fails
Which fuel line does the fuel come from that goes through the IDG heat exchanger?
The HP fuel line
Where does the fuel return to after it travels through the IDG heat exchanger?
the Outer tank
IDG cooling is ensured when….?
Oil temp is high, or
when engine is at low power
How is the IDG heat exchanger fuel return valve?
FADEC
Where does the IDG cooling fuel go if the Outer tank is already full?
Overflows into the Inner tank via a spill pipe
In what order does automatic refuelling fill the aircrafts fuel tanks?
- Outer tank and Centre tank (if required) simultaneously
2. When Outer tank full, fuel overflows to Inner tank
In what order does manual refuelling fill the aircrafts fuel tanks?
- Wing tanks
2. Centre tank
What may stop the automatic refuelling process?
Electrical transients caused by switching among APU, external and engine electrical supply
If automatic refuelling is stopped due to electrical transient what must be done to resume refuelling?
re-enter the Pre-selected Fuel Quantity
When will the centre fuel tank recieve fuel during refuelling?
If the selected fuel load exceeds wing tank capacity of 12 252 kg
Can the aircraft be refuelled when only battery power is available?
Yes
How long will it take to refuel wing tanks?
17 mins
How long will it take to refuel all tanks?
20 mins
What does the FQI (fuel quantity indicator) computerised system do?
- Transmits actual total fuel mass, quantity and temperature to ECAM
- Controls automatic refuelling
How many channels does the FQI have?
2
What happens if FQI channel 1 fails?
Channel 2 activates automatically
The components of the FQI system
- an FQI computer
- a set of capacitance probes in each tank (measure fuel level and temperature)
- a densiometer sensor in each Inner tank (calculate fuel quantity
- a capacitance Index Compensator (CIC) in each Inner tank giving dielectric constant of fuel (in case of densiometer failure)
- a quantity indicator for each tank installed on the refuel/defuel panel
- a pre-selector on the refuel/defuel panel that shows pre-selected and actual total fuel quantity
The Fuel Level Sensing Control Unit comprises…..
- fuel level sensors in tanks to sense High, Low and Overflow levels
- a fuel temperature sensor to control the IDG cooling recirculation
What does the Fuel Level System do?
Generates fuel-level and fuel-temp signals to:
Operate switching functions for refuel/defuel, and
Control IDG cooling recirculation system, and
Centre tank to Wing tank fuel transfer System
When does the low-level sensor trigger the LO LVL warning on the ECAM?
When fuel quantity in one wing tank goes below 750kg
Is the LO LVL warning totally independent from the displayed fuel quantity indication?
Yes! Its sensed by the FLSCU
Quantity indication is calculated by the FQI
L (R) Tank Pumps ON -blank
Pump is ON, but only feeds fuel when the delivery pressure of the centre tank pumps drop below the threshold
When will L (R) / Centre Tank pump FAULT light illuminate?
plus ECAM caution
When delivery pressure drops
With MODE SEL in AUTO, when are the centre tank pumps controlled?
- run at engine start for 2mins
- Before or after engine start, centre tank pumps run if slats are retracted
- Centre tank pumps stop 5 mins after centre tank low level is reached
When will the MODE SEL pb FAULT light illuminate (with ECAM caution)?
When centre tank has more than 250 kg fuel, and
L/R wing tank has less than 5000kg fuel
When will the fuel temperature indication appear?
when its associated temperature sensor is wet
When will a fuel temperature advisory appear?
Inner >45°C
Outer >55°C
Below -40°C
What do two dashes mean when over the last two fuel quantity digits?
The FQI is inaccurate
What is meant if the Outer fuel quantity indication is boxed amber?
Both transfer valves have failed to open - Inner tank at low level (750kg)
When will centre tank fuel quantity be boxed amber?
If both centre tank pumps fail or are switched OFF
How is a wing overflow indicated?
associated Inner tank quantity turns amber
When will a fuel quantity advisory appear?
When difference between fuel quantities in wings is greater than 1500kg
How is a fuel quantity advisory indicated?
wing inner and outer tank indications pulse with highest fuel level
What would cause FOB to be half-boxed (boxed-YUD) amber?
- Centre tank pumps fail or switched OFF
- Both transfer valves failto open, when inner tank is low level (750kg)
When is the engine identification number amber instead of white?
When the engine is below idle
When is fuel used indication green?
From flight phase 2 until electrical power is cut off at the end of the flight
When does the fuel used indication automatically reset?
When the engine is started on the ground
When will an amber half box appear around the Total Fuel Indication?
When displayed quantity is not all useable.
intercell transfer valve fail or centre tank pump fail
If two dashes over fuel quantity, then FQI is in degraded mode. Where will you find the fuel adjustment figures for this problem?
FCOM DSC-28-20 pg15/16
What does the green REFUELG memo mean?
The door of the refuel panel is open
