. 
40000 

30000 

20000  . 

10000 

0  . 

Fuel Weight (kg)
. 
 Outer tanks

. 
 Inner tanks

. 
 Center tank

. 
 A300-600 and  A310-300: ACT 1 (if applicable)

. 
 A300-600R and  A310-300 : Trim tank

. 
 A300-600 and  A310-300:

-20 -10  0  102030  405060  -20 -10  0  1020 3040 5060  ACT 2 (if applicable) 
Delta Index  Delta Index 
Refueling vector A300-600R  Refueling vector A310-300 with 2ACTs 

The graphs below give an example of the fuel vector impact on the certified CG envelope:
170 160
160 150
150 140

Weight (tonnes)
140
130
120 130
120
110110 100
100 90 90
A300-600 (no ACT)  A310-300 (1 ACT)
SYSTEMS

B. FUEL SYSTEMS

4.4. In-flight CG travel
The normal fuel burn with no consideration of the CG control system is as follows:
. 1/ ACT 2 then ACT 1 (when applicable) fuel transferred in the center tank
. 2/ Center tank
. 3/ Inner tanks
. 4/ Trim tank fuel transferred progressively in the center tank until the trim
tank is empty
. 5/ Center tank
. 6/ Outer tanks
As explained previously, the Autofeed system controls the fuel feed sequence.
Automatic fuel transfer from ACT to the center tank occurs when center tank high level has been dry for ten minutes. It stops when the center tank high level is rewetted.
Once the inner tanks are empty, the CGCC generates a forward fuel transfer from the trim tank to the center tank.
The normal depletion vector is a reference that is not actually fulfilled as the CG position is impacted by the CG control system.
4.5. CG control system
Only A300-600R and A310-300 are equipped with a trim tank and an associated CG control system. Center of Gravity control and monitoring is achieved by the CGCC (Center of Gravity Control Computer). The CGCC has three main functions:
. To compute the aircraft CG and gross weight based on the ZFCG and ZFW
(entered by the crew in the CDU), the fuel quantity in each tank and the aircraft
pitch angle.
. To monitor the CG and maintain a CG target
. To order fuel transfers in order to maintain the CG target.
As for long-range aircraft, the CG target is defined as a function of the aircraft weight. It also

CG target A310-300
SYSTEMS

During takeoff and landing, the trim tank is isolated. The trim tank isolation valve opens at takeoff when the slats are retracted and closes at landing when the gear is down.
B. FUEL SYSTEMS

SYSTEMS

CG control is activated above FL 205. In climb below FL 205, forward transfers can be initiated if the aircraft reaches its aft CG target. However, no aft transfer is permitted. Above FL205, the CGCC initiates fuel transfers in order to maintain the CG within 0.5% forward of the CG target. As for the long-range family, this starts with an aft fuel transfer (normally only one per flight) and continues with forward fuel transfers to compensate for the fuel burn.
　
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