DOC AIRBUS | AMM A320FAUXILIARY FUEL MANAGEMENT COMPUTER (AFMC) - OPERATIONAL USE - DESCRIPTION AND OPERATION
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1. General
When the Additional Center Tank/s (ACT/s) are not installed the Auxiliary Fuel Management Computer (AFMC):
When the ACT/s are installed the AFMC also:
** ON A/C NOT FOR ALL When the Additional Center Tank/s (ACT/s) are not installed the Auxiliary Fuel Management Computer (AFMC):
- Gives indication of the individual fuel quantities in the wing and center tanks (it gets this Aeronautical Radio INCorporated (ARINC) data from the Fuel Quantity Indication Computer (FQIC) (Ref. AMM D/O 28-42-00-00))
- Gives indication of the total (ACTUAL) fuel on board
- Gives indication of the fuel temperature and the position of the intercell transfer valves (it gets this information from the FQIC (Ref. AMM D/O 28-42-00-00))
- Gives the fuel quantity data to other systems in the aircraft
- Retransmits FQIC ARINC data to other systems in the aircraft (but not to the CFDS).
When the ACT/s are installed the AFMC also:
- Identifies which ACTs are installed
- Controls the auto mode refuel of the ACTs (Ref. AMM D/O 28-25-00-00)
- Calculates the fuel quantity in each ACT
- Gives individual ACT fuel quantities to an indicator in the cockpit
- Adds the total ACT fuel quantity to the wing/center tank quantity to give the total (ACTUAL) fuel on board quantity
- Gives total ACT and individual ACT fuel quantities to an indicator at the refuel/defuel panel
- Controls the auto mode fuel transfer from the ACT/s to the center tank
- Monitors the operation of the components in the ACT system
- Gives data to the Electronic Centralized Aircraft Monitoring (ECAM) System Display (SD) (FUEL page) to show when fuel transfer occurs
- Gives discrete outputs and ARINC data to the Central Warning System (Ref. AMM D/O 31-52-00-00) when faults occur in the ACT system
- Keeps a record of the ACT system faults found during the last flight.
2. Component Location
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Auxiliary Fuel Management Computer (AFMC) - Component Location| FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
| ** ON A/C NOT FOR ALL | |||||
| 2QN | COMPUTER-AUXILIARY FUEL MANAGEMENT | 121 | 28-51-35 | ||
3. System Description
The AFMC gets ARINC and the discrete inputs from the other fuel control and monitors the systems. The ARINC data comes from the FQIC (Ref. AMM D/O 28-42-00-00):
The discrete inputs enable the AFMC to identify:
The Auxiliary Fuel Management System (AFMS) outputs fuel quantity data via the ARINC buses to:
The discrete outputs:
The AFMC gets ARINC and the discrete inputs from the other fuel control and monitors the systems. The ARINC data comes from the FQIC (Ref. AMM D/O 28-42-00-00):
The discrete inputs enable the AFMC to identify:
The Auxiliary Fuel Management System (AFMS) outputs fuel quantity data via the ARINC buses to:
The discrete outputs:
** ON A/C NOT FOR ALL NOTE: For NEO aircraft with an ACT installed in the forward cargo compartment, the term ACT FWD can also be described as ACT 4.1.
During normal operation, the two channels of the AFMC each channel get their own 28VDC power supply. Each supply comes from a different bus bar. During refuel the two channels share a common 28VDC supply from the refuelling bus. At all times these two channels operate as master and slave. The AFMC gets ARINC and the discrete inputs from the other fuel control and monitors the systems. The ARINC data comes from the FQIC (Ref. AMM D/O 28-42-00-00):
- The fuel quantities of the individual wing and the center tanks
- The total fuel quantity of the wing and the center tanks
- The fuel density of the wing and the center tanks
- The fuel temperature of the wing tanks
- The effective pitch and roll of the aircraft
- The preselected fuel quantity
- The wing and the center tank refuel abort status.
The discrete inputs enable the AFMC to identify:
- The number of ACT(s) installed
- The status of the aircraft (on the ground or in the air) (Ref. AMM D/O 32-62-00-00)
- The quantity of fuel to show for a specified ACT
- The open or closed status of the valves in the ACT pressurization/vent system (Ref. AMM D/O 28-28-00-00)
- The open or closed status of the valves in the ACT refuel/fuel transfer system (Ref. AMM D/O 28-28-00-00)
- The open or closed status of the ACT isolation valves
- The status of the high level sensors in the wing and the center tanks
- The status of the Auxiliary Level Sense Control Unit (ALSCU) and its high and low level sensors
- The status of the ACT FWD break wire
- The status of the refuel-panel preselector transmission fault discrete
- The status of the cockpit control pushbuttons
- The status of the automatic refuel mode
- The power source (main/ground services or battery)
- The status of the Centralized Fault Display System (CFDS) BITE request.
The Auxiliary Fuel Management System (AFMS) outputs fuel quantity data via the ARINC buses to:
- The fuel quantity indication on the ECAM fuel system page
- The fuel quantity indicator at the refuel panel
- The fuel quantity preselector at the refuel panel.
The discrete outputs:
- Control the operation of the hardwired relay logic to give full auto control of the ACT refuel operation and the fuel transfer to the center tank
- Give an indication when the faults occur in the ACT system
- Give an indication at the SD (FUEL page) when the fuel transfer occurs
- Supply a signal to do a test of the ALSCU and the installed high and low level sensors.
The AFMC gets ARINC and the discrete inputs from the other fuel control and monitors the systems. The ARINC data comes from the FQIC (Ref. AMM D/O 28-42-00-00):
- The fuel quantities of the individual wing and the center tanks
- The total fuel quantity of the wing and the center tanks
- The fuel density of the wing and the center tanks
- The fuel temperature of the wing tanks
- The effective pitch and roll of the aircraft
- The preselected fuel quantity
- The wing and the center tank refuel abort status.
The discrete inputs enable the AFMC to identify:
- The number of ACT(s) installed
- The status of the aircraft (on the ground or in the air) (Ref. AMM D/O 32-62-00-00)
- The quantity of fuel to show for a specified ACT
- The open or closed status of the valves in the ACT pressurization/vent system (Ref. AMM D/O 28-28-00-00)
- The open or closed status of the valves in the ACT refuel/fuel transfer system (Ref. AMM D/O 28-28-00-00)
- The open or closed status of the ACT isolation valves
- The status of the high level sensors in the wing and the center tanks
- The status of the Auxiliary Level Sense Control Unit (ALSCU) and its high and low level sensors
- The status of the refuel-panel preselector transmission fault discrete
- The status of the cockpit control pushbuttons
- The status of the automatic refuel mode
- The power source (main/ground services or battery)
- The status of the Centralized Fault Display System (CFDS) BITE request.
The Auxiliary Fuel Management System (AFMS) outputs fuel quantity data via the ARINC buses to:
- The fuel quantity indication on the ECAM fuel system page
- The fuel quantity indicator at the refuel panel
- The fuel quantity preselector at the refuel panel.
The discrete outputs:
- Control the operation of the hardwired relay logic to give full auto control of the ACT refuel operation and the fuel transfer to the center tank
- Give an indication when the faults occur in the ACT system
- Give an indication at the SD (FUEL page) when the fuel transfer occurs
- Supply a signal to do a test of the ALSCU and the installed high and low level sensors.
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6. Component Description
A. Auxiliary Fuel Management Computer (AFMC) FIN: 2-QN
The AFMC has a 3MCU case that:
The AFMC has a 3MCU case that:
- Holds a number of circuit boards
- Protects the circuit boards from vibration
- Supplies an EMC shield for the internal electronic components.
An ARINC 600 connector at the rear of the case supplies the interface with the electronics rack in the aircraft. Three polarization pins installed below the connector are set to a specified configuration. This makes sure that the AFMC can only be installed in its correct location in the rack.
The AFMC has two CPU boards that are the same, one PSU board, a mother board (with an ARINC 600 connector board) and one interconnection board. Guide rails at the top and the bottom of the case align the circuit boards with the mother board installed at the rear of the case. The interconnection board is installed at the front of the case and supplies the connection between the CPU and the PSU boards.
7. Operation/Control and Indicating
At power up the BITE of the AFMC will calculate the status of each channel. If the two channels can calculate the individual ACT fuel quantities and control the auto fuel transfer sequence then channel 1 will be the master. A changeover of master channels can occur during the system operation if the initial master channel cannot do all that is necessary.
Only the master channel gives the discrete outputs to the hardwired relay control logic and the interface systems. If some ACTs are not installed the discrete outputs to the relay logic of those ACTs are disabled. The fuel quantity indicator in the cockpit will show OFF at the related quantity displays to identify these ACTs to the flight crew.
Auto Refuel:
The AFMC will identify an auto refuel when it finds that:
During automatic refuel, if necessary, refuel of any targeted ACTs will occur at the same time as the wing and the centre tanks. If, at the start of the refuel, the AFMC calculates a fuel target value for more than one ACT, the installed ACT/s will fill at the same time.
When the refuel bus gives the power supply then only those components necessary for auto refuel will get power.
During auto refuel the two AFMC channels will do the refuel function. If the master channel has a fault during the sequence the slave channel will become the master channel and complete the refuel.
The auto refuel sequence will start when:
If the preselected fuel quantity is more than the capacity of the wing and the center tanks (the FQIC controls the refuel of these tanks) the AFMC will calculate the necessary fuel target value for each ACT.
The AFMC will:
When the fuel quantity in ACT AFT1 gets to the target value the AFMC will close the inlet valve. The inlet valve can open and close a maximum of three times to get the target value.
When the fuel level in ACT AFT1 gets to high level the ALSCU will:
If the AFMC or the FQIC stop the refuel before it is complete, the END lamp on the refuel panel will flash.
Fuel quantities:
Each channel of the AFMC gets an analog input from a fuel probe in each installed ACT. The AFMC also gets an ARINC input from the FQIC which gives the fuel quantities in the wing and the center tanks.
The AFMC calculates:
The AFMC sends ARINC data to:
The fuel quantities given will be:
Fuel transfer:
When the aircraft status changes from "on the ground" to "in the air" (right hand main landing gear retracted and no weight on wheels) the AFMC will open the air shut off valve (233QM). It will also close the ACT vent valve (234QM) to pressurize the system. Each installed ACT will be included in the auto sequence which will start from the next ACT in the sequence. This means each ACT inlet valve will open for a minimum period of 60 seconds even if the tank is empty.
Auto transfer of fuel to the center tank will start when the center tank contents are less than 5000 kg (11023.1100 lb). When the fuel quantity in the center tank is more than 5750 kg (12676.5765 lb) or the ACT is empty the related fuel inlet valve will close. Fuel transfer from the next ACT in the sequence will occur when the necessary conditions are available.
The ECAM FUEL SD page will show an arrow in green outline when an automatic fuel transfer occurs (ACT transfer valve and relevent fuel inlet valve open).
When the aircraft status changes from "in the air" to "on the ground" (right hand main landing gear extended and weight on wheels) the AFMC will close the air shut-off valve (233QM). It will also open the vent valve (234QM) to vent the installed ACTs.
** ON A/C NOT FOR ALL At power up the BITE of the AFMC will calculate the status of each channel. If the two channels can calculate the individual ACT fuel quantities and control the auto fuel transfer sequence then channel 1 will be the master. A changeover of master channels can occur during the system operation if the initial master channel cannot do all that is necessary.
Only the master channel gives the discrete outputs to the hardwired relay control logic and the interface systems. If some ACTs are not installed the discrete outputs to the relay logic of those ACTs are disabled. The fuel quantity indicator in the cockpit will show OFF at the related quantity displays to identify these ACTs to the flight crew.
Auto Refuel:
The AFMC will identify an auto refuel when it finds that:
- The aircraft is on the ground
- The switch (3QU) at the refuel panel (800VU) is set to REFUEL
- All the refuel valve selector switches are set to NORMAL.
During automatic refuel, if necessary, refuel of any targeted ACTs will occur at the same time as the wing and the centre tanks. If, at the start of the refuel, the AFMC calculates a fuel target value for more than one ACT, the installed ACT/s will fill at the same time.
When the refuel bus gives the power supply then only those components necessary for auto refuel will get power.
During auto refuel the two AFMC channels will do the refuel function. If the master channel has a fault during the sequence the slave channel will become the master channel and complete the refuel.
The auto refuel sequence will start when:
- The refuel bus has been energized for more than seven seconds
(this delay lets the high level sensors get to their correct state) - The preselected fuel quantity is set to 100 kg (220 lb) more than the actual fuel quantity on board.
If the preselected fuel quantity is more than the capacity of the wing and the center tanks (the FQIC controls the refuel of these tanks) the AFMC will calculate the necessary fuel target value for each ACT.
The AFMC will:
- Command the ACT refuel valve (41QU) open (the refuel valve will not open until the ACT inlet valve opens)
- Open the inlet valve (228QM1) of ACT AFT1.
When the fuel quantity in ACT AFT1 gets to the target value the AFMC will close the inlet valve. The inlet valve can open and close a maximum of three times to get the target value.
When the fuel level in ACT AFT1 gets to high level the ALSCU will:
- Close the inlet valve
- Put the applicable high level light on at the refuel panel.
If the AFMC or the FQIC stop the refuel before it is complete, the END lamp on the refuel panel will flash.
Fuel quantities:
Each channel of the AFMC gets an analog input from a fuel probe in each installed ACT. The AFMC also gets an ARINC input from the FQIC which gives the fuel quantities in the wing and the center tanks.
The AFMC calculates:
- The fuel quantity in each installed ACT
- The total fuel quantity of the ACTs
- The total (actual) fuel quantity on board (ACT total plus wing and center tank quantity).
The AFMC sends ARINC data to:
- The Electronic Instrument System (EIS) to show the useable fuel quantity in each ACT (ACTs that are not fitted are shown on the Fuel page), each integral tank and the total fuel on board
- The Flight Warning Computers (FWCs) to trigger alerts related to the fuel quantities
- The Flight Management and Guidance Computers (FMGCs) for reference speed and fuel prediction calculations
- The Flight Data Interface and Management Unit (Data Management Unit (DMU) part) for fuel quantity recording
- The indicator at the refuel panel, to show the wing tank and the center tank quantities, individual ACT and TOTAL ACT quantities. A rotary selector switch lets you set which individual ACT quantity is shown
- The preselector at the refuel panel to show the PRESELECTED fuel quantity and the ACTUAL fuel on board.
The fuel quantities given will be:
- Updated every second
- Shown to a resolution of 10 kg (22 lb) for each tank
- Shown to a resolution of 100 kg (220 lb) for the total.
Fuel transfer:
When the aircraft status changes from "on the ground" to "in the air" (right hand main landing gear retracted and no weight on wheels) the AFMC will open the air shut off valve (233QM). It will also close the ACT vent valve (234QM) to pressurize the system. Each installed ACT will be included in the auto sequence which will start from the next ACT in the sequence. This means each ACT inlet valve will open for a minimum period of 60 seconds even if the tank is empty.
Auto transfer of fuel to the center tank will start when the center tank contents are less than 5000 kg (11023.1100 lb). When the fuel quantity in the center tank is more than 5750 kg (12676.5765 lb) or the ACT is empty the related fuel inlet valve will close. Fuel transfer from the next ACT in the sequence will occur when the necessary conditions are available.
The ECAM FUEL SD page will show an arrow in green outline when an automatic fuel transfer occurs (ACT transfer valve and relevent fuel inlet valve open).
When the aircraft status changes from "in the air" to "on the ground" (right hand main landing gear extended and weight on wheels) the AFMC will close the air shut-off valve (233QM). It will also open the vent valve (234QM) to vent the installed ACTs.
8. Test
There are no special menus on the MCDU or reset buttons on the AFMC for the maintenance personnel to request an AFMC/system test.
A test switch (2QJ) is available at the refuel panel (800VU). This switch lets you do a check of the high level sensors and the high level indicators (Ref. 28-42-00). When the switch is set to HI LVL a 28VDC output goes from the refueling bus to the AFMC, ALSCU, FQIC, FLSCU1 and FLSCU2 (Ref. AMM D/O 28-46-00-00). This output causes the ALSCU and the FLSCUs to invert their high level sensor outputs (puts a ground on) and each high level indicator comes on to show that its related sensor is serviceable.
You can cause each channel of the AFMC to do a reset if you remove the power supply for a specified time. During each power up sequence the AFMC BITE will make specified tests.
After a power interrupt of more than 220 milliseconds, each channel will do a test (warm start) to make sure that it can operate in a safe and correct manner. If the test is not satisfactory a channel will set itself as unserviceable and the other channel will become the master.
When the aircraft is on the ground and a power interrupt of more than five seconds occurs, each channel will do a test (cold start) that includes the warm start test.
The master channel will test the high level sensors through the ALSCU and continue the test that follows if:
The test will include the AFMC BITE drive and specified ALSCU discrete outputs.
It will also include an operational test of the forward ACT isolation valve (236QM) and the forward ACT vent isolation valve (232QM). Each valve will be set to closed then to open.
During the test these conditions will be monitored:
A test switch (2QJ) is available at the refuel panel (800VU). This switch lets you do a check of the high level sensors and the high level indicators (Ref. 28-42-00). When the switch is set to HI LVL a 28VDC output goes from the refueling bus to the AFMC, ALSCU, FQIC, FLSCU1 and FLSCU2 (Ref. AMM D/O 28-46-00-00). This output causes the ALSCU and the FLSCUs to invert their high level sensor outputs (puts a ground on) and each high level indicator comes on to show that its related sensor is serviceable.
You can cause each channel of the AFMC to do a reset if you remove the power supply for a specified time. During each power up sequence the AFMC BITE will make specified tests.
After a power interrupt of more than 220 milliseconds, each channel will do a test (warm start) to make sure that it can operate in a safe and correct manner. If the test is not satisfactory a channel will set itself as unserviceable and the other channel will become the master.
When the aircraft is on the ground and a power interrupt of more than five seconds occurs, each channel will do a test (cold start) that includes the warm start test.
The master channel will test the high level sensors through the ALSCU and continue the test that follows if:
The test will include the AFMC BITE drive and specified ALSCU discrete outputs.
There are no special menus on the MCDU or reset buttons on the AFMC for the maintenance personnel to request an AFMC/system test.
A test switch (2QJ) is available at the refuel panel (800VU). This switch lets you do a check of the high level sensors and the high level indicators (Ref. 28-42-00). When the switch is set to HI LVL a 28VDC output goes from the refueling bus to the AFMC, ALSCU, FQIC, FLSCU1 and FLSCU2 (Ref. AMM D/O 28-46-00-00). This output causes the ALSCU and the FLSCUs to invert their high level sensor outputs (puts a ground on) and each high level indicator comes on to show that its related sensor is serviceable.
You can cause each channel of the AFMC to do a reset if you remove the power supply for a specified time. During each power up sequence the AFMC BITE will make specified tests.
After a power interrupt of more than 220 milliseconds, each channel will do a test (warm start) to make sure that it can operate in a safe and correct manner. If the test is not satisfactory a channel will set itself as unserviceable and the other channel will become the master.
When the aircraft is on the ground and a power interrupt of more than five seconds occurs, each channel will do a test (cold start) that includes the warm start test.
The master channel will test the high level sensors through the ALSCU and continue the test that follows if:
- The power supply discrete indicates main power on
- A forward ACT FWD is installed
- The fuel transfer pipe to the forward ACTs is not damaged
- The vent pipe to the forward ACTs is not damaged
- The FWD ACT OVRD P/BSW (43QH) (at cockpit panel 28VU) is not pushed.
The test will include the AFMC BITE drive and specified ALSCU discrete outputs.
It will also include an operational test of the forward ACT isolation valve (236QM) and the forward ACT vent isolation valve (232QM). Each valve will be set to closed then to open.
During the test these conditions will be monitored:
- The closed status will be monitored for ten seconds
- The open status will be monitored for ten seconds.
A test switch (2QJ) is available at the refuel panel (800VU). This switch lets you do a check of the high level sensors and the high level indicators (Ref. 28-42-00). When the switch is set to HI LVL a 28VDC output goes from the refueling bus to the AFMC, ALSCU, FQIC, FLSCU1 and FLSCU2 (Ref. AMM D/O 28-46-00-00). This output causes the ALSCU and the FLSCUs to invert their high level sensor outputs (puts a ground on) and each high level indicator comes on to show that its related sensor is serviceable.
You can cause each channel of the AFMC to do a reset if you remove the power supply for a specified time. During each power up sequence the AFMC BITE will make specified tests.
After a power interrupt of more than 220 milliseconds, each channel will do a test (warm start) to make sure that it can operate in a safe and correct manner. If the test is not satisfactory a channel will set itself as unserviceable and the other channel will become the master.
When the aircraft is on the ground and a power interrupt of more than five seconds occurs, each channel will do a test (cold start) that includes the warm start test.
The master channel will test the high level sensors through the ALSCU and continue the test that follows if:
- The power supply discrete indicates main power on.
The test will include the AFMC BITE drive and specified ALSCU discrete outputs.