B. FUEL SYSTEMS
3.2.3. Control and indication
On long range family aircraft, the fuel system (FCMS : Fuel Control and Monitoring System) is
controlled by two Fuel Control and Monitoring Computers (FCMCs). Their main functions are:
. Fuel transfer control
. Aircraft gross weight and CG position calculation
. Center of gravity control
. Refuel control
. Fuel quantity measurement and indication on ECAM and on refuel control panel.
A340-200/-300 ECAM fuel page A340-500 ECAM fuel page
In normal operation, one FCMC is active while the other is in stand-by.
Fuel quantity calculation performed by FCMC is based on the following information:
. Fuel volume from tank probes
. Fuel density from densitometers
. Horizontal stabilizer angle
. Aircraft attitude
. Fuel electrical characteristics from compensators
On A340-500/-600, the tank data (volume, density, electrical characteristics and temperature) is provided to the FCMCs via two Fuel Data Concentrators (FDC).
Fuel level sensors also provide the FCMC with information used to control transfers and to trigger warnings independently of the fuel quantity indication.
SYSTEMS
SYSTEMS
B. FUEL SYSTEMS
The following diagram presents the fuel system architecture:
ACARS
54
B. FUEL SYSTEMS
3.3. CG travel during refueling
During automatic refueling, once a fuel quantity has been selected, all the tanks are filled simultaneously according to a given fuel distribution. The following graph is published in FCOM
2.01.30 and enables to determine the fuel distribution in each tank at the end of refueling as a function of the total fuel quantity:
Refueling distribution A340-300 FCMS 7.0
FCMS modifications have been introduced in order to optimize the fuel sequences by reducing the fuel vector range. The following information is based on FCMS 9.0 (10.0), which is the production standard at the date of the publication, and on the fuel tank capacities mentioned above. Please refer to the Weight and Balance Manual for applicable information.
3.3.1. A330-200-300 and A340-200/-300
The refueling sequence for A330 and A340-200/-300 is as follows:
120000
110000 .
100000
90000 .
80000 .
70000
60000
50000 .
40000
30000 .
20000 .
10000
0. .
.
inner tanks up to 4500 kg per side
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