B. FUEL SYSTEMS
4.2. Fuel Systems
4.2.1. Engine feed and fuel transfers
Each of the five main fuel tanks (inner, outer and center tank) is equipped with two fuel pumps. Engines are fed: . From the center tank when the aircraft is on ground and in flight when slats are retracted. The pumps supply both engines simultaneously. . From inner tanks at takeoff, with slats extended and when the center tank is empty. . From the outer tanks when the inner and center tanks are empty. The pumps in the outer tanks are kept on throughout the flight.
When the aircraft is equipped with ACT(s), the fuel is transferred in the center tank by pressurization. ACT fuel transfer pump is used on ground and in case of the pressurization system failure. This transfer is inhibited during trim forward transfer to the center tank.
The tail trim tank (when applicable) is fitted with two transfer pumps for aft transfers generated by the CG control system.
4.2.2. Control and indication
The FQI (Fuel Quantity Indicating) computer provides the crew with fuel quantity information by
processing data from:
. A fuel specific gravity sensor (Cadensicon)
. An attitude sensor which provides with aircraft pitch attitude and bank angle
. A compensator probe in each tank for the fuel dielectric characteristics The resulting fuel quantity is displayed on the ECAM fuel page, on the fuel quantity indicator on the overhead panel and on the external fuel panel. The FQI uses this information to monitor the refueling by closing the refuel valves when the preset quantities are reached.
The Fuel Autofeed System controls the inner tanks and center tank pumps according to the normal fuel feed sequence. The Autofeed system is activated when at least one pump pushbutton is switched in NORMAL position for each inner tank and for the center tank. The outer tank pumps are not managed by the Autofeed system. They run continuously during the flight.
Contrary to the long-range family, the center of gravity control system is independent of the fuel feed and the refueling system. The CGCC (Center of Gravity Control Computer) controls the transfers from and to the trim tank.
SYSTEMS
50000 . .
.
40000
.
30000
20000
10000 .
0 .
B. FUEL SYSTEMS
4.3. CG Travel during refueling
Tanks are refueled in the following order: 60000
60000
Fuel Weight (kg)
.
50000
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