|
Surge
tank |
Outer
wing tank 1560
lbs. (N/A
321) |
Inner
wing tank 12,190
lbs. |
Center
tank 14,500
lbs. |
Inner
wing tank 12,190
lbs. |
Outer
wing tank 1560
lbs. (N/A
321) |
Surge
tank |
|
A321
only: 2
Additional Center Tanks 10,500
lbs |
|
|
|
|
|
|
A319/320:
|
Total
Left Wing Fuel 13,750 |
Total
Center Fuel 14,500
lbs. |
Total
Right Wing Fuel 13,750 |
|
Total
Left Wing Fuel 13,750 |
Total Center Fuel 25,000 lbs. |
Total Right
Wing Fuel 13,750 |
Total Fuel
– A319/320: 42,000 lbs., A321: 52,500 lbs. (memory limitation)
Fuel Philosophy: Fuel in center last, Center fuel emptied
first
Takeoff on center tank prohibited (PH 2.8.3)
Fuel may not be added to ACT unless center tank is full
(A321).
The center tank pumps run at a higher override pressure
(A319, A320) so the center tank fuel will be burned before the wing tank fuel
will be even though center and wing pumps are both providing fuel pressure to
the manifold at the same time.
If both pumps in same tank fail, only the inner wing tanks
can suction feed. Center tank fuel would be unusable.
Normally fuel is run in Auto mode. This will run the wing
tanks continuously and the center tank on a schedule. The Auto mode schedule
for the center tank is to run the center tank pumps any time there is fuel in
the center tank except when the slats are extended. Exceptions to the Auto
schedule (PH 9.1.7):
Ø
After the center tanks run dry the pumps will continue to
run for 5 more mins.
Ø
If IDG return fuel fills the outer wing tank the extra fuel
will spill over into the inner wing tank. If the inner wing tank fills
completely up then the center tank pump on that side will be automatically
turned off to allow wing tank fuel to be burned until 1,100 lbs. has been used.
Then the center tank pump will turn on again. This prevents surge tank
spillage.
The fuel in the outer wing tanks will gravity feed through
two transfer valve openings when inner wing tank fuel level reaches 1,650 lbs.
When either wing inner tank reaches the 1,650 lbs. level a signal is sent to
latch open all the transfer valves in both outer wing tanks. This is a total of
4 valves, 2 in each outer wing tank. The transfer valves will remain open for
the rest of the flight and will close on the next refuel operation. If fuel is
“sloshed” during climb or descent it is possible for the transfer valves to be
opened early due to a LO LEVEL alert.
An ECAM caution is given if during Auto mode the center tank
has more than 550 lbs. of fuel while the left or right wing tank has less than
11,000 lbs. of fuel per wing. This would indicate that the normal Auto schedule
was not being followed.
The Crossfeed pb is normally extinguished when the valve is
closed. It will show blue ON when selected on and green OPEN when fully open.
There are two full levels for the inner wing tanks, a
fueling full and an operational full. The fueling full is less than the
operational full and that allows the extra IDG fuel room to collect in normal
circumstances without triggering the center tank pump turn-off for IDG return
fuel.
Note: In Auto the center tank pumps run all the time if
center tank fuel is present so with all fuel pumps on if you are on the gate
with APU running (slats up) you will be using center tank fuel. If operating in
Manual mode the crew must ensure that the center tank pumps are off when the
wing tanks are completely full or when the center tank is empty.
Note: Unusable fuel is shown with a half amber box around
the fuel quantity on ECAM. If the fuel quantity is in a degraded mode the ECAM
fuel quantity will have amber dashes through the last two digits. Refuel is
shown on upper ECAM memo when refueling door is open.
A321 differences:
The A321 Center Tank does not have the same electric pumps
as the A319/320 but uses jet pumps instead. Further, the jet pumps are
“powered” by fuel pressure from the fuel pumps in the main wing tanks and the
jet pumps transfer fuel from the Center tank to the respective wing tank. The
A321 wing tanks do not have an outer and inner tank and there are no transfer
valves to latch open. All the wing fuel is in one wing tank and total wing fuel
remains the same as the A319/320. Please understand that the pumps in the wing
must be running in order to power the center tank jet pumps and transfer fuel.
The center tanks pump pb’s have been replaced on the A321
with transfer valve pb’s. Essentially these CNT TK L (R) XFR pb’s handle the
same function as the center tank pb’s on the A319 and A320. In Auto mode they
will control the valves that allow the jet pumps to operate once the wing fuel
has been burned down 550 lbs. Once the wing fuel tank is again full the
transfer will stop until the tank is burned down 550 lbs. again. This will
continue until all center fuel has been used. If the FUEL MODE SEL pb is in MAN
then the center tank transfer valves will open and must be turned off to avoid
overfilling the wing tanks. If in MAN they should also be turned OFF once all
center tank fuel is gone.
Note: IDG return
fuel is added to the wing tank as there is no outer tank on the A321.
Note: There is no ECAM OUTR TK FUEL XFRD memo on the A321 as there is no outer or inner wing tank
(all fuel in one wing tank).
The A321 has two Additional Center Tanks that will
automatically feed to the Center tank when the Center tank burns down to a
certain level. The Additional Center Tanks do not have pumps but use cabin air
pressure to feed the center tank through transfer valves. The ACT 2 (aft tank)
will transfer fuel first followed by the ACT1. All fuel transfer is done
automatically in the normal mode of operation. The automatic fuel transfer from
ACT to Center Tank is noted on the ECAM as a green triangle between the ACT
fuel indicators.
An additional pb has been added to the FUEL panel to control
the ACT fuel transfer. Yes, you guessed it, the normal mode is AUTO (are we
seeing a pattern here?). In AUTO mode the ACT pb allows automatic control of
the fuel transfer after slat retraction when in-flight. Fuel transfer will
begin from the ACT 2 when the center tank is no longer full. Transfer will
continue until either the center tank is full or both ACT’s are empty. After
ACT transfer starts if the center tank becomes full transfer will stop until
the center tank burns down sufficiently and the transfer process will
automatically restart.
|
ACT 1 (forward) |
|
ACT 2 (aft) |
An amber FAULT light will illuminate in the ACT pb if the
center tank has less than 6,614 lbs. of fuel and one ACT has more than 550 lbs.
of fuel which would indicate that the AUTO schedule was not being followed. If
the ACT pb is selected to FWD then all ACT fuel will be manually transferred
forward to the center tank using the ACT transfer pump, which is a backup pump
that can pump from either ACT. This backup ACT XFR pump runs at a low volume
and may not be able to transfer all fuel at higher altitudes (FL270 and above)
or supply as fast as the engines are burning. Chapter 21 will specify best
procedures for complete transfer of fuel in case of ACT transfer FAULT.
It is normal to have fuel being transferred from the ACT’s
to the Center tank and from the Center tank to the Wing tanks at the same time.
On the A321 there’s a whole lotta transferring goin’ on. Please note that in
order to feed an engine from the opposite wing you must still open the fuel
crossfeed valve. In normal AUTO operation the fuel procedures are the same and
fuel transfer operation is transparent to the pilot.
Note: For the A321
all fuel is burned from the Wing tanks. Fuel must be transferred to a Wing tank
for it to be available for use by the engines. There is no ECAM CTR TANK FEEDG
memo as the A321 never feeds from the Center Tank.
Note: For A321: if
center tank is not full then do not takeoff with fuel in an ACT (PH
2.8.3)
Note: on the SD FUEL display the left ACT is #1 (forward) and the right ACT is #2 (aft). Gee, why not just display them as fore and aft?