DOC AIRBUS | AMM A320FEIS - SWITCHING - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
Various reconfiguration possibilities are provided in the Electronic Instrument System (EIS) in order to cope with the operational requirements below in case of failure of a Display Management Computer (DMC), a Display Unit (DU) or a Control Panel (EFIS control section of the Flight Control Unit (FCU) or ECAM Control Panel) :
** ON A/C NOT FOR ALL Various reconfiguration possibilities are provided in the Electronic Instrument System (EIS) in order to cope with the operational requirements below in case of failure of a Display Management Computer (DMC), a Display Unit (DU) or a Control Panel (EFIS control section of the Flight Control Unit (FCU) or ECAM Control Panel) :
EFIS/ECAM Reconfigurations Between DMCs and Between DUs- DMC transfer : EIS DMC 1/3 or 2/3 (DMC 3 replaces DMC 1 or 2)
- PFD-ND transfer
- ECAM DU transfer : upper DU to lower DU
- ECAM-ND transfer : ECAM/CAPT ND or ECAM/F/O ND.
2. Links Between DMCs and DUs
The PFD, ND, ECAM processing channels of a DMC drive their associated DUs through a switching stage and via dedicated links called Master DSDL (Dedicated Serial Data Link).
The Master DSDL conveys instructions and data.
In certain conditions, programs are teleloaded from the DMCs to the DUs via this DSDL.
More particularly, this teleloading operation takes place at DMC initialization (electrical power on setting) if the program stored in the EPROM of the DUs does not match the operational program stored in the DMC memory modules.
Another kind of teleloading process takes place from the DMC to the dedicated RAMs of the ECAM DU at each change of aircraft system image.
The DUs are all versatile, i.e. each DU is able to display any of the EIS or ECAM images. (However, the ECAM DU cannot display PFD/ND images).
In normal operation, the DMC 1 drives the CAPT PFD, the CAPT ND and the upper ECAM DU through their normal input N.
The DMC 2 drives the F/O PFD, the F/O ND and the lower ECAM DU also through their normal input N (the DMC 3 is in standby, ready to take over from the DMC 1 or 2 in case of failure).
In fact, each DU has two inputs to receive the digital signals from the DMC dedicated buses (master DSDL), one normal input N and one alternate input A (This alternate input is used in some reconfiguration cases following transfer control as explained in the paragraph concerning DU failures).
In turn, each DU sends to its driving DMC digital signals through a dedicated bus which is called feedback DSDL. Through this feedback link, the DUs acknowledge proper reception of the DSDL master signals, and also inform the DMC of their detected failures, so that the DMC can make the proper action (for instance, automatic transfer of a PFD image on an ND in case of detected failure of the PFD).
** ON A/C NOT FOR ALL The PFD, ND, ECAM processing channels of a DMC drive their associated DUs through a switching stage and via dedicated links called Master DSDL (Dedicated Serial Data Link).
The Master DSDL conveys instructions and data.
In certain conditions, programs are teleloaded from the DMCs to the DUs via this DSDL.
More particularly, this teleloading operation takes place at DMC initialization (electrical power on setting) if the program stored in the EPROM of the DUs does not match the operational program stored in the DMC memory modules.
Another kind of teleloading process takes place from the DMC to the dedicated RAMs of the ECAM DU at each change of aircraft system image.
The DUs are all versatile, i.e. each DU is able to display any of the EIS or ECAM images. (However, the ECAM DU cannot display PFD/ND images).
In normal operation, the DMC 1 drives the CAPT PFD, the CAPT ND and the upper ECAM DU through their normal input N.
The DMC 2 drives the F/O PFD, the F/O ND and the lower ECAM DU also through their normal input N (the DMC 3 is in standby, ready to take over from the DMC 1 or 2 in case of failure).
In fact, each DU has two inputs to receive the digital signals from the DMC dedicated buses (master DSDL), one normal input N and one alternate input A (This alternate input is used in some reconfiguration cases following transfer control as explained in the paragraph concerning DU failures).
In turn, each DU sends to its driving DMC digital signals through a dedicated bus which is called feedback DSDL. Through this feedback link, the DUs acknowledge proper reception of the DSDL master signals, and also inform the DMC of their detected failures, so that the DMC can make the proper action (for instance, automatic transfer of a PFD image on an ND in case of detected failure of the PFD).
NOTE: The connections between the DMC 3 and the DUs are crosswired for the PFD and ND, in order to cope with a possible wire cut-off of the connection which delivers the PFD information.
In this case, when the DMC 3 supplies the PFD and the ND on one side, CAPT or F/O, the DMC 3 signals enter the PFD and the ND via their alternate inputs.
The activation of the DU alternate inputs and the deactivation of the normal inputs is made by the grounding of a discrete input on the DU connector. This is achieved by an A/C circuitry which takes into account all the conditions that lead to the change of inputs (normal or alternate).
In this case, when the DMC 3 supplies the PFD and the ND on one side, CAPT or F/O, the DMC 3 signals enter the PFD and the ND via their alternate inputs.
The activation of the DU alternate inputs and the deactivation of the normal inputs is made by the grounding of a discrete input on the DU connector. This is achieved by an A/C circuitry which takes into account all the conditions that lead to the change of inputs (normal or alternate).
NOTE: All of the DMCs and DUs know their position aboard the A/C by A/C wiring : straps connected or not connected.
3. EIS Switching Operation
A. EIS DMC Switching
There are no cross-talk links between the three DMCs, in order to ensure complete segregation of CAPT and F/O displays.
Inside the DMCs, downstream of the PFD, ND, ECAM channels, there are switching relays for the DSDLs.
In the event of DMC 1 (or DMC 2) failure, the Captain (or First Officer) can switch over to DMC 3. This is controlled by means of the EIS DMC selector switch (CAPT/3 or F/O/3 position).
In this case, the DMC 3 totally replaces the DMC 1 (or 2) through the stage of the output switching relay of the failed DMC.
As explained in the previous section, the connections between the DMC 3 PFD and ND channels and the PFDs and NDs are cross-wired.
Therefore, it is necessary to send the DMC 3 PFD and ND signals to the Alternate inputs of the PFDs and NDs, so that the PFD and ND images remain at their normal location.
The relay box (CAPT or F/O) does the selection of the alternate inputs of the PFDs and NDs.
In case of selection of the DMC 3, both the master DSDL and the feedback DSDL buses are switched in the DMC 1 (or 2) output switching stage.
There are no cross-talk links between the three DMCs, in order to ensure complete segregation of CAPT and F/O displays.
Inside the DMCs, downstream of the PFD, ND, ECAM channels, there are switching relays for the DSDLs.
In the event of DMC 1 (or DMC 2) failure, the Captain (or First Officer) can switch over to DMC 3. This is controlled by means of the EIS DMC selector switch (CAPT/3 or F/O/3 position).
In this case, the DMC 3 totally replaces the DMC 1 (or 2) through the stage of the output switching relay of the failed DMC.
As explained in the previous section, the connections between the DMC 3 PFD and ND channels and the PFDs and NDs are cross-wired.
Therefore, it is necessary to send the DMC 3 PFD and ND signals to the Alternate inputs of the PFDs and NDs, so that the PFD and ND images remain at their normal location.
The relay box (CAPT or F/O) does the selection of the alternate inputs of the PFDs and NDs.
NOTE: In the event of DMC failure, the DUs driven by this DMC display a diagonal line, which helps the crew to make immediately the right action.
The DMC 3 acts as a back up (hot spare). When the EIS DMC selector switch is in NORM position, the DMC 3 works like the DMC 1 as regards the selection of all the input sources, so as to be readily available to take over the driving of the CAPT PFD and ND and of the upper ECAM DU, with minimum transfer delay, as soon as the pilots place the ECAM/ND XFR selector switch in CAPT/3 position. In case of selection of the DMC 3, both the master DSDL and the feedback DSDL buses are switched in the DMC 1 (or 2) output switching stage.
B. Switching of the EIS DUs (PFD-ND)
(1) Manual PFD/ND transfer
A manual transfer facility (by means of PFD/ND XFR P/BSW) enables each pilot to cross-change the images which are displayed on his PFD and ND at any time : at each action on this pushbutton switch, there is an inversion between the two images : the one which was displayed on the left DU is displayed on the right DU and vice versa.
A manual transfer facility (by means of PFD/ND XFR P/BSW) enables each pilot to cross-change the images which are displayed on his PFD and ND at any time : at each action on this pushbutton switch, there is an inversion between the two images : the one which was displayed on the left DU is displayed on the right DU and vice versa.
(2) Transfer of the PFD image on the ND
(a) In case of detected failure of the DU which normally displays the PFD image, there is an automatic PFD/ND transfer. The PFD image is presented on the DU which normally shows an ND image.
This automatic transfer is controlled by means of a discrete signal generated by the DMC upon recognition of the failure (NORMAL PFD INVALID).
This automatic transfer is controlled by means of a discrete signal generated by the DMC upon recognition of the failure (NORMAL PFD INVALID).
(b) This pilot can also obtain manually this transfer, by either of the two following means :
- either deactivate the PFD through the ON-OFF/brightness potentiometer set to OFF: this automatically transfers the PFD image on the ND and the PFD image replaces the ND image,
- or press the PFD/ND XFR pushbutton switch.
- either deactivate the PFD through the ON-OFF/brightness potentiometer set to OFF: this automatically transfers the PFD image on the ND and the PFD image replaces the ND image,
- or press the PFD/ND XFR pushbutton switch.
(3) Transfer of the ND image on the PFD
If the ND is deactivated (corresponding ON-OFF/brightness potentiometer set to OFF), or if the ND fails, there is no automatic transfer of the ND image on the PFD.
However, the pilot can recover the display of the ND image on the remaining DU, which normally shows the PFD image, by means of the PFD/ND XFR pushbutton switch.
If the ND is deactivated (corresponding ON-OFF/brightness potentiometer set to OFF), or if the ND fails, there is no automatic transfer of the ND image on the PFD.
However, the pilot can recover the display of the ND image on the remaining DU, which normally shows the PFD image, by means of the PFD/ND XFR pushbutton switch.
(4) Operation
The PFD and ND transfers are controlled by the choice of the NORMAL and ALTERNATE inputs of the PFD and ND. For a given side (CAPT or F/O), an A/C circuitry sends a discrete signal in parallel to the PFD and ND on their AA-25 contact :
The PFD and ND transfers are controlled by the choice of the NORMAL and ALTERNATE inputs of the PFD and ND. For a given side (CAPT or F/O), an A/C circuitry sends a discrete signal in parallel to the PFD and ND on their AA-25 contact :
(a) If the EIS DMC selector switch is in the NORM position, this signal is a ground when the PFD image is to be displayed on the ND and the ND image on the PFD. In this case, the ALTERNATE inputs are selected for both DUs. This signal is an open circuit if the PFD and ND images are to be displayed at their normal location, the PFD image on the PFD, and the ND image on the ND.
(b) If the EIS DMC selector switch is in CAPT/3 (or F/O/3) position, the ground and open circuit states of the discrete signal are inverted with respect to the previous case (EIS DMC selector switch in NORM position), because of the cross-wiring of the PFD and ND DSDLs.
The CAPT and the F/O relay boxes perform all the above functions by controlling the state of their A-Y2 contact.
Note that each pilot can always change the output state of each relay box to restore the desired display configuration by means of the PFD ND XFR pushbutton switch.
The CAPT and the F/O relay boxes perform all the above functions by controlling the state of their A-Y2 contact.
Note that each pilot can always change the output state of each relay box to restore the desired display configuration by means of the PFD ND XFR pushbutton switch.
NOTE: When setting on the electrical power, a given relay box immediately controls the A-Y2 contact output state which corresponds to that required by the PFD ON-OFF/brightness potentiometer, the NORM PFD INV signal and the EIS DMC selector switch, indepently of the last state before de-energizing the A/C electrical network and assuming that the PFD/ND XFR P/BSW has not yet been pressed.
The relay boxes keep their present output state whatever it is, in case of 28VDC electrical power supply transient of less than 200ms. But, in case of loss of the 28VDC electrical power supply, the output of the affected relay box has the open circuit state after 300ms.
The relay boxes perform the switching of discrete signals concerning the selection for the DME audio signals: the DME audio outputs are associated with the audio outputs of the VOR or ILS receivers (ILS if the ROSE-ILS mode is selected or if the ILS P/BSW has been pressed). This configuration is sent by the DMCs in use (1 or 3 and 2 or 3) to the Audio Management Unit.
The relay boxes keep their present output state whatever it is, in case of 28VDC electrical power supply transient of less than 200ms. But, in case of loss of the 28VDC electrical power supply, the output of the affected relay box has the open circuit state after 300ms.
The relay boxes perform the switching of discrete signals concerning the selection for the DME audio signals: the DME audio outputs are associated with the audio outputs of the VOR or ILS receivers (ILS if the ROSE-ILS mode is selected or if the ILS P/BSW has been pressed). This configuration is sent by the DMCs in use (1 or 3 and 2 or 3) to the Audio Management Unit.
C. Switching of the ECAM DUs (Upper ECAM DU - Lower ECAM DU and ECAM/ND Transfer)
(1) Transfer from the upper ECAM DU to the lower ECAM DU
In the event of upper ECAM DU failure, the Engine/Warning image is displayed on the lower ECAM DU instead of the system page or status message. This switching is automatic : on reception of the upper DU anomaly signal, through the feedback DSDL bus, the DMC 2 ECAM channel processor switches by software to an ECAM single display configuration which privileges the E/W processing.
The lower ECAM DU receives the E/W image from the DMC 2, still through its NORMAL input. The same applies when the UPPER DISPLAY potentiometer is set to OFF.
In case of lower ECAM DU failure, the Engine/Warning image remains displayed on the upper ECAM DU, but it is also a single display configuration. The single display configuration is called MONO display configuration (M). More generally, it corresponds to any situation with only one DU for all the ECAM information. The image which is displayed is pratically the same as an Engine/Warning image (minor difference concerning the Advisories, as explained).
In case of single display configuration, the E/W image can be temporarily replaced by any A/C system page or by the status page, as long as the corresponding key is maintained pressed on the ECAM control panel. When the pilot releases the key, the E/W image appears again.
In the event of upper ECAM DU failure, the Engine/Warning image is displayed on the lower ECAM DU instead of the system page or status message. This switching is automatic : on reception of the upper DU anomaly signal, through the feedback DSDL bus, the DMC 2 ECAM channel processor switches by software to an ECAM single display configuration which privileges the E/W processing.
The lower ECAM DU receives the E/W image from the DMC 2, still through its NORMAL input. The same applies when the UPPER DISPLAY potentiometer is set to OFF.
In case of lower ECAM DU failure, the Engine/Warning image remains displayed on the upper ECAM DU, but it is also a single display configuration. The single display configuration is called MONO display configuration (M). More generally, it corresponds to any situation with only one DU for all the ECAM information. The image which is displayed is pratically the same as an Engine/Warning image (minor difference concerning the Advisories, as explained).
In case of single display configuration, the E/W image can be temporarily replaced by any A/C system page or by the status page, as long as the corresponding key is maintained pressed on the ECAM control panel. When the pilot releases the key, the E/W image appears again.
(2) ECAM-ND transfer
By means of the ECAM/ND XFR selector switch, each pilot can call on his ND an ECAM image (normally A/C system or status image, or Engine/Warning image if both ECAM DUs are inoperative) instead of the ND image.
Obviously, the pilots can at any time get their ND image back when they set the selector switch back to NORM.
By means of the ECAM/ND XFR selector switch, each pilot can call on his ND an ECAM image (normally A/C system or status image, or Engine/Warning image if both ECAM DUs are inoperative) instead of the ND image.
Obviously, the pilots can at any time get their ND image back when they set the selector switch back to NORM.
(3) Survey of the various ECAM display configurations
The following table gives the various possible ECAM display configurations according to the availability of the ECAM processing channels in the DMCs and the ECAM DUs. The list is not exhaustive.
The management of all the possible ECAM display configurations requires the three DMCs exchanging between them information on their working configuration for ECAM display. To this end, each DMC generates a wired discrete signal: ECAM CHANNEL AVAIL, which signals that its ECAM processor is valid and it is in relation with one valid ECAM DU. Each DMC sends this signal to the two others.
The DMC in charge of displaying an ECAM image on its related ECAM DU then knows which image to draw: E/W (in Normal or in Single display mode) or System/Status and through which input this image must be sent to the ECAM DU: NORMAL or ALTERNATE. To this end, it sends a wired discrete signal in parallel to the two ECAM DUs (ECAM DU ALTERNATE CONTROL) in the following cases:
* ECAM/ND F/O transfer and DMC 1 ALTERNATE CONTROL demand (such is the case when the upper ECAM DU has failed)
* ECAM/ND CAPT transfer and DMC 2 ALTERNATE CONTROL demand (such is the case when the lower ECAM DU has failed).
The two ECAM DUs always use their Normal or their Alternate input simultaneously.
At last, the following table gives the operational consequences after the loss of one or several EIS items of equipment.
The following table gives the various possible ECAM display configurations according to the availability of the ECAM processing channels in the DMCs and the ECAM DUs. The list is not exhaustive.
| ------------------------------------------------------------------------------- |
| NR DMC1,2,3 CREW XFR DISPATCHING OF ECAM IMAGES |
| COND SELECTION CAPT ND UPPER DU LOWER DU F/O ND |
| ------------------------------------------------------------------------------- |
| 1 NORM NORM ND E/W (N) S (N) ND |
| DMC1 IN E/W DMC2 IN S |
| 2 NORM ECAM/ND F/O ND E/W (N) NIL S (N) |
| DMC1 IN E/W DMC2 IN S |
| 3 NORM ECAM/ND CAPT S (N) NIL E/W (N) ND |
| DMC1 IN S DMC2 IN E/W |
| 4 DMC1 NORM NIL NIL E/W (N) ND |
| FAILED DMC2 IN M |
| 5 DMC2 NORM ND E/W (N) NIL NIL |
| FAILED DMC1 IN M |
| 6 NORM NORM ND DU E/W (N) ND |
| FAILED DMC2 IN M |
| 7 NORM ECAM/ND F/O ND DU E/W (A) S (N) |
| FAILED DMC1 IN E/W DMC2 IN S |
| 8 NORM ECAM/ND CAPT S (N) DU E/W (N) ND |
| FAILED DMC2 IN E/W |
| 9 NORM NORM ND E/W (N) DU ND |
| DMC1 IN M FAILED |
| 10 NORM ECAM/ND F/O ND E/W (N) DU S (N) |
| DMC1 IN E/W FAILED DMC2 IN S |
| 11 NORM ECAM/ND CAPT S (N) E/W (A) DU ND |
| DMC2 IN E/W FAILED |
| 12 NORM ECAM/ND F/O ND DU DU E/W (N) |
| FAILED FAILED DMC2 IN M |
| 13 NORM ECAM/ND CAPT E/W (N) DU DU ND |
| FAILED FAILED |
NOTE: Each DMC ECAM channel can operate in either E/W mode, or S mode, or M (Memo or Single ECAM display mode).
N = NORMAL INPUT
A = ALTERNATE INPUT
N = NORMAL INPUT
A = ALTERNATE INPUT
NOTE: Normally, the DMC which is on the CAPT side always drives the upper ECAM DU and the DMC which is on the F/O side always drives the lower ECAM DU.
When the ECAM/ND XFR selector switch is set to CAPT, the System (or Status) image is displayed on the CAPT ND, and the Engine/Warning image is displayed on the lower ECAM DU, to inform the crew that this image is generated by the DMC2.
When the ECAM/ND XFR selector switch is set to CAPT, the System (or Status) image is displayed on the CAPT ND, and the Engine/Warning image is displayed on the lower ECAM DU, to inform the crew that this image is generated by the DMC2.
The management of all the possible ECAM display configurations requires the three DMCs exchanging between them information on their working configuration for ECAM display. To this end, each DMC generates a wired discrete signal: ECAM CHANNEL AVAIL, which signals that its ECAM processor is valid and it is in relation with one valid ECAM DU. Each DMC sends this signal to the two others.
The DMC in charge of displaying an ECAM image on its related ECAM DU then knows which image to draw: E/W (in Normal or in Single display mode) or System/Status and through which input this image must be sent to the ECAM DU: NORMAL or ALTERNATE. To this end, it sends a wired discrete signal in parallel to the two ECAM DUs (ECAM DU ALTERNATE CONTROL) in the following cases:
* ECAM/ND F/O transfer and DMC 1 ALTERNATE CONTROL demand (such is the case when the upper ECAM DU has failed)
* ECAM/ND CAPT transfer and DMC 2 ALTERNATE CONTROL demand (such is the case when the lower ECAM DU has failed).
The two ECAM DUs always use their Normal or their Alternate input simultaneously.
| TABLE: ECAM DISPLAY CONFIGURATIONS |
| ------------------------------------------------------------------------------- |
| !CASE!DMC1/2/3! CREW ! DISPATCHING OF ECAM IMAGES : ! |
| ! NR !CONDITN !TRANSFER ! DU INPUT (N or A) - SOURCE DMC and ! |
| ! ! !SELECTION! ECAM PROCESSOR OPERATING MODE(E/W - S - MONO ) ! |
| ! ! ! !------------------------------------------------------ |
| ! ! ! ! CAPT ND ! UP ECAM DU ! LO ECAM DU ! F/O ND ! |
| ------------------------------------------------------------------------------- |
| ! 1 ! NORM ! NORM ! ND ! E/W (N) ! S(N) ! ND ! |
| ! ! ! ! !DMC1 in E/W ! DMC2 in S ! ! |
| ! 2 ! NORM ! ECAM/ND ! ND ! E/W (N) ! / ! S (N) ! |
| ! ! ! F/O ! !DMC1 in E/W ! (diagonal) ! DMC2 in S ! |
| ! 3 ! NORM ! ECAM/ND ! S (N) ! / ! E/W (N) ! ND ! |
| ! ! ! CAPT ! DMC1 in S ! (diagonal) !DMC2 in E/W ! ! |
| ! 4 ! DMC1 ! NORM ! / ! / ! E/W (N) ! ND ! |
| ! ! FAILED ! ! (diagonal) ! !DMC2 in MONO! ! |
| ! 5 ! DMC2 ! NORM ! ND ! E/W (N) ! / ! / ! |
| ! ! FAILED ! ! !DMC1 in MONO! ! ! |
| ! 6 ! NORM ! NORM ! ND ! X ! E/W (N) ! ND ! |
| ! ! ! ! !(DU failed) !DMC2 in MONO! ! |
| ! 7 ! NORM !ECAM/ND ! ND ! X ! E/W (A) ! S (N) ! |
| ! ! ! F/O ! !(DU failed) !DMC1 in E/W ! DMC2 in S ! |
| ! 8 ! NORM ! ECAM/ND ! S (N) ! X ! E/W (N) ! ND ! |
| ! ! ! CAPT ! DMC1 in S !(DU failed) ! DMC2 in E/W! ! |
| ! 9 ! NORM ! NORM ! ND ! E/W (N) ! X ! ND ! |
| ! ! ! ! !DMC1 in MONO!(DU failed) ! ! |
| ! 10 ! NORM ! ECAM/ND ! ND ! E/W (N) ! X ! S (N) ! |
| ! ! ! F/O ! !DMC1 in E/W !(DU failed) ! DMC2 in S ! |
| ! 11 ! NORM ! ECAM/ND ! S (N) ! E/W (A) ! X ! ND ! |
| ! ! ! CAPT ! DMC1 in S !DMC2 in E/W !(DU failed) ! ! |
| ! 12 ! NORM ! ECAM/ND ! ND ! X ! X ! E/W (N) ! |
| ! ! ! F/O ! !(DU failed) !(DU failed) ! DMC2 in MONO ! |
| ! 13 ! NORM ! ECAM/ND ! E/W (N) ! X ! X ! ND ! |
| ! ! ! CAPT !DMC1 in MONO!(DU failed) !(DU failed) ! ! |
At last, the following table gives the operational consequences after the loss of one or several EIS items of equipment.
| ------------------------------------------------------------------------------ |
| ! FAILURE ! OPERATIONAL CONSEQUENCE ! |
| !-------------!--------------------------------------------------------------! |
| ! 1DMC ! NO ! |
| !-------------!--------------------------------------------------------------! |
| ! 2DMCs ! - Loss of PFD and ND images on either CAPT or F/O instrument ! |
| ! ! panel. ! |
| ! ! - Loss of ECAM System/Status image (possibility to display ! |
| ! ! a System or Status image temporarily). ! |
| !-------------!--------------------------------------------------------------! |
| ! 1 EIS DU ! Loss of ND image on the corresponding main instrument panel. ! |
| ! ! Possibility to get the ND image back by means of the PFD ND ! |
| ! ! XFR P/BSW. ! |
| !-------------!--------------------------------------------------------------! |
| ! FCU single ! In case of FCU channel 1 (or 2) failure, the DMCs still ! |
| ! failure ! receive the FCU channel 2 (1) information, which carries ! |
| ! ! along all the CAPT and F/O selections. There is an automatic ! |
| ! ! switch over inside the FCU. ! |
| !-------------!--------------------------------------------------------------! |
| ! UPPER ECAM ! Automatic transfer of the Engine/Warning (E/W) image on the ! |
| ! DU ! lower ECAM DU and subsequent loss of the System/Status ! |
| ! ! image. ! |
| ! ! - Possibility to display the S image temporarily instead of ! |
| ! ! the E/W image when a key is pressed on the ECAM control ! |
| ! ! panel. ! |
| ! ! - Possibility to display the S image permanently on either ! |
| ! ! ND instead of the ND image by means of the ECAM/ND XFR ! |
| ! ! selector switch. ! |
| !-------------!--------------------------------------------------------------! |
| ! LOWER ECAM ! Loss of the S image. Possibility to get it back temporarily ! |
| ! DU ! or permanently (same as above). ! |
| !-------------!--------------------------------------------------------------! |
| ! BOTH ECAM ! Loss of Engine/Warning and System images. Possibility to ! |
| ! DUs ! have the Engine/Warning image displayed on either ND by ! |
| ! ! means of the ECAM/ND XFR selector switch. Possibility to ! |
| ! ! display momentarily the S image instead of the E/W image. ! |
| !-------------!--------------------------------------------------------------! |
| ! ! In case of an electronic failure concerning the ECAM CP, the ! |
| ! ! following functions remain available : ALL, CLR, RCL, CANC, ! |
| ! ! since the corresponding keys are directly wired to the DMCs. ! |
| ! ! By means of the ALL key, the pilot can access any A/C System ! |
| ! ! image. ! |
| !-------------!--------------------------------------------------------------! |
NOTE: When there is only one DU left for the ECAM display, priority is given to the E/W image display. However, should any monitored parameter exceed its corresponding ADVISORY threshold, the ADV white message flashes on the lower part of the E/W image.
On the ECAM CP, the key of the affected A/C system flashes in order to enable the pilot to find it easily and to consult the corresponding system image temporarily if he presses the key.
On the ECAM CP, the key of the affected A/C system flashes in order to enable the pilot to find it easily and to consult the corresponding system image temporarily if he presses the key.
D. Switching of the DMC Output Buses
The DMCs transmit data on two ARINC 429 buses : one high speed switched bus and one low speed unswitched bus.
Switched means : when a pilot sets the EIS DMC selector switch to CAPT/3 (or F/O/3), the DMC 1 (or DMC 2 respectively) sends through its output bus the data received from the DMC 3, instead of its own data.
The HS switched bus conveys data to the FDIU (for the DFDR), FWCs, ECAM CP. The LS unswitched bus sends maintenance data (DMC BITE contents) for the CFDIU.
The DMCs transmit data on two ARINC 429 buses : one high speed switched bus and one low speed unswitched bus.
Switched means : when a pilot sets the EIS DMC selector switch to CAPT/3 (or F/O/3), the DMC 1 (or DMC 2 respectively) sends through its output bus the data received from the DMC 3, instead of its own data.
The HS switched bus conveys data to the FDIU (for the DFDR), FWCs, ECAM CP. The LS unswitched bus sends maintenance data (DMC BITE contents) for the CFDIU.
4. Switching of the Various Onside & Offside DMC Input Buses
The following tables give the three kinds of buses (ARINC 429, ARINC 453 (for the W/R), RS 422) received by the three DMCs.
In addition, they define which bus each DMC uses, in the normal case (N) and in the alternate case (A), i.e. when the Normal source is not available.
In the column PROCESSED BY DMC No. 1 2, X means : the DMC constantly processes the corresponding bus. The failure of this bus does not cause a switching of the DMC to another source. More often, the corresponding flag(s) appears on the DUs.
Normally, the DMC 1 and 2 use their onside sources for display: e.g., the DMC 1 uses the ADC 1, IRS 1, FMGC 1,... buses and likewise for the DMC 2 (ADC 2, IRS 2, FMGC 2, ...).
Behaviour of the DMC 3 is identical to that of the DMC 1 when the EIS DMC selector switch is on NORM or CAPT/3 and to that of the DMC 2 when the EIS DMC selector switch is on F/O/3.
When the EIS DMC selector switch is set to NORM or CAPT/3 the DMC 1 or DMC 3 is called: DMC ON SIDE 1. When the selector switch is set F/O/3, the DMC 2 or DMC 3 is called: DMC ON SIDE 2.
In case of failure of a given source, the DMC switches over to the corresponding offside source (e.g. FAC 2, FQI 2, ... for the DMC 1), or to the No. 3 source (in the case of the ADR and IR buses). This switching is automatic in the former case and manual in the latter case.
As regards the radio-nav sources (ILS, VOR, DME, ADF), there is no switching, neither automatic nor manual.
The following tables give the three kinds of buses (ARINC 429, ARINC 453 (for the W/R), RS 422) received by the three DMCs.
In addition, they define which bus each DMC uses, in the normal case (N) and in the alternate case (A), i.e. when the Normal source is not available.
In the column PROCESSED BY DMC No. 1 2, X means : the DMC constantly processes the corresponding bus. The failure of this bus does not cause a switching of the DMC to another source. More often, the corresponding flag(s) appears on the DUs.
| ------------------------------------------------------------------------------ |
| ! ! SPEED ! ! ! ! |
| ! ! (HIGH ! WIRED ! ! ! |
| ! ! SPEED,! TO DMC! PROCESSED ! ! |
| ! ! LOW ! No. ! BY DMC No.! ! |
| ! ! SPEED)! 1 2 3 ! 1 2 ! ! |
| !-------------------!-------!-------!-----------!----------------------------! |
| ! ADIRU : IR BUS 1 ! HS ! X X ! N ! For CAPT : A if CAPT ! |
| ! 2 ! HS ! X X ! N ! selects ATT/HDG CAPT/3 on ! |
| ! 3 ! HS ! X X X ! A A ! the SWITCHING panel. ! |
| ! ! ! ! ! Ditto for DMC 2. ! |
| !-------------------!-------!-------!-----------!----------------------------! |
| ! ADIRU : ADR BUS 1 ! LS ! X X ! N ! For CAPT : A if CAPT ! |
| ! 2 ! LS ! X X ! N ! selects ADC INST CAPT/3 on ! |
| ! 3 ! LS ! X X X ! A A ! the SWITCHING panel. ! |
| ! ! ! ! ! Ditto for DMC 2. ! |
| !-------------------!-------!-------!-----------!----------------------------! |
| ! FAC 1 ! HS ! X X X ! N A ! Selection following FAC ! |
| ! 2 ! HS ! X X X ! A N ! validity (healthy signal ! |
| ! ! ! ! ! and bus validity) and ADC ! |
| ! ! ! ! ! INST switching ! |
| !-------------------!-------!-------!-----------!----------------------------! |
| ! FMGC : A BUS 1 ! HS ! X X X ! N A ! FD (if selected) or FMA ! |
| ! (FGC) 2 ! HS ! X X X ! A N ! information taken from ! |
| ! ! ! ! ! onside or offside bus ! |
| ! ! ! ! ! according to availability ! |
| !-------------------!-------!-------!-----------!----------------------------! |
| ! FMGC : EIS BUS 1 ! HS ! X X X ! N A ! Selection following bus ! |
| ! (FMC) 2 ! HS ! X X X ! A N ! validity (healthy signal ! |
| ! ! ! ! ! and bus validity) ! |
| ------------------------------------------------------------------------------ |
| ------------------------------------------------------------------------------ |
| ! ! SPEED ! ! ! ! |
| ! ! (HIGH ! WIRED ! ! ! |
| ! ! SPEED,! TO DMC! PROCESSED ! ! |
| ! ! LOW ! No. ! BY DMC No.! ! |
| ! ! SPEED)! 1 2 3 ! 1 2 ! ! |
| !-------------------!-------!-------!-----------!----------------------------! |
| ! FCU 1-1 ! LS ! X X ! X ! Inside FCU, switching on ! |
| ! 1-2 ! LS ! X X ! X ! processor 2 in case of ! |
| ! 2-1 ! LS ! X X ! X ! failure of processor 1 ! |
| ! 2-2 ! LS ! X X ! X ! ! |
| !-------------------!-------!-------!-----------!----------------------------! |
| ! VOR 1 ! LS ! X X X ! X X ! ! |
| ! 2 ! LS ! X X X ! X X ! ! |
| !-------------------!-------!-------!-----------!----------------------------! |
| ! ILS 1 ! LS ! X X X ! X X ! ILS1<--> PFD-CAPT & ND-F/O ! |
| ! 2 ! LS ! X X X ! X X ! ILS2<--> PFD-F/O & ND-CAPT ! |
| ! ! ! ! ! in standard definition ! |
| !-------------------!-------!-------!-----------!----------------------------! |
| ! R/A 1 ! LS ! X X X ! N A ! ! |
| ! 2 ! LS ! X X X ! A N ! ! |
| !-------------------!-------!-------!-----------!----------------------------! |
| ! DME 1 ! LS ! X X X ! X X ! ! |
| ! 2 ! LS ! X X X ! X X ! ! |
| !-------------------!-------!-------!-----------!----------------------------! |
| ! ADF 1 ! LS ! X X X ! X X ! ! |
| ------------------------------------------------------------------------------ |
| ------------------------------------------------------------------------------ |
| ! ! SPEED ! ! ! ! |
| ! ! (HIGH ! WIRED ! ! ! |
| ! ! SPEED,! TO DMC! PROCESSED ! ! |
| ! ! LOW ! No. ! BY DMC No.! ! |
| ! ! SPEED)! 1 2 3 ! 1 2 ! ! |
| !-------------------!-------!-------!-----------!----------------------------! |
| ! W/R 1-1 ! ARINC ! X X X ! N (N) ! On CAPT side : ! |
| ! 1-2 ! 453 ! X X X ! (N) N ! - automatic selection ! |
| ! 2-1 ! (very ! X X X ! A (A) ! 1-1/1-2 --> 2-1/2-2 for ! |
| ! 2-2 ! high ! X X X ! (A) A ! DMC1 when W/R XCVR2 active ! |
| ! ! speed)! ! ! instead of W/R XCVR1 ! |
| ! ! ! ! ! - automatic inhibition of ! |
| ! ! ! ! ! 1-1 if FMGC 1 EIS bus ! |
| ! ! ! ! ! invalid. ! |
| ! ! ! ! ! Ditto on F/O side ! |
| ! ! ! ! ! (with respective buses) ! |
| !-------------------!-------!-------!-----------!----------------------------! |
| ! FWC 1-1 ! HS ! X ! X ! If not valid on onside ! |
| ! 1-2 ! HS ! X ! X ! bus, label is taken from ! |
| ! 1-3 ! HS ! X ! ! offside bus ! |
| ! 2-1 ! HS ! X ! X ! ! |
| ! 2-2 ! HS ! X ! X ! ! |
| ! 2-3 ! HS ! X ! ! ! |
| !-------------------!-------!-------!-----------!----------------------------! |
| ! 1-1 ! RS 422! X ! N ! A when FWC 1-X RS422 bus ! |
| ! 1-2 ! RS 422! X ! N ! is seen faulty ! |
| ! 1-3 ! RS 422! X ! ! ! |
| ! 2-1 ! RS 422! X ! A ! ! |
| ! 2-2 ! RS 422! X ! A ! ! |
| ! 2-3 ! RS 422! X ! ! ! |
| !-------------------!-------!-------!-----------!----------------------------! |
| ! SDAC 1 ! HS ! X X X ! X X ! ! |
| ! 2 ! HS ! X X X ! X X ! ! |
| ------------------------------------------------------------------------------ |
| ------------------------------------------------------------------------------ |
| ! ! SPEED ! ! ! ! |
| ! ! (HIGH ! WIRED ! ! ! |
| ! ! SPEED,! TO DMC! PROCESSED ! ! |
| ! ! LOW ! No. ! BY DMC No.! ! |
| ! ! SPEED ! 1 2 3 ! 1 2 ! ! |
| !-------------------!-------!-------!-----------!----------------------------! |
| ! ECU 1 A1 ! LS ! X X ! X ! A when ECU 1 (2) primary ! |
| ! (FADEC 1 A2 ! LS ! X ! X ! channel A1 (or B1) fails. ! |
| ! system) 1 B1 ! LS ! X X ! X X ! If not valid on channel in ! |
| ! 1 B2 ! LS ! X ! ! control, label is taken ! |
| ! 2 A1 ! LS ! X X ! X ! from the other channel. ! |
| ! 2 A2 ! LS ! X ! X ! ! |
| ! 2 B1 ! LS ! X X ! X X ! ! |
| ! 2 B1 ! LS ! X ! ! ! |
| !-------------------!-------!-------!-----------!----------------------------! |
| ! ECAM CTL PNL 2 ! LS ! X X X ! N N ! ! |
| !-------------------!-------!-------!-----------!----------------------------! |
| ! FQI 1-A ! LS ! X X ! N ! A when the channel ! |
| ! 1-B ! LS ! X ! N ! superiority signal controls! |
| ! 2-A ! LS ! X ! A ! the change over to the ! |
| ! 2-B ! LS ! X X ! A ! other bus, or when the ! |
| ! ! ! ! ! normal bus becomes faulty ! |
| !-------------------!-------!-------!-----------!----------------------------! |
| ! CFDIU (GENERAL ! LS ! X X X ! X X ! ! |
| ! O/P INTERROGATION ! ! ! ! ! |
| ! BUS) ! ! ! ! ! |
| !-------------------!-------!-------!-----------!----------------------------! |
| ! FCDC 1 ! LS ! X X X ! X X ! If not valid on onside ! |
| ! 2 ! ! X X X ! X X ! bus, label is taken from ! |
| ! ! ! ! ! the offside bus. ! |
| !-------------------!-------!-------!-----------!----------------------------! |
| ! LGCIU 1 ! LS ! X X X ! X X ! ! |
| ! 2 ! LS ! X X X ! X X ! ! |
| !-------------------!-------!-------!-----------!----------------------------! |
Normally, the DMC 1 and 2 use their onside sources for display: e.g., the DMC 1 uses the ADC 1, IRS 1, FMGC 1,... buses and likewise for the DMC 2 (ADC 2, IRS 2, FMGC 2, ...).
Behaviour of the DMC 3 is identical to that of the DMC 1 when the EIS DMC selector switch is on NORM or CAPT/3 and to that of the DMC 2 when the EIS DMC selector switch is on F/O/3.
When the EIS DMC selector switch is set to NORM or CAPT/3 the DMC 1 or DMC 3 is called: DMC ON SIDE 1. When the selector switch is set F/O/3, the DMC 2 or DMC 3 is called: DMC ON SIDE 2.
In case of failure of a given source, the DMC switches over to the corresponding offside source (e.g. FAC 2, FQI 2, ... for the DMC 1), or to the No. 3 source (in the case of the ADR and IR buses). This switching is automatic in the former case and manual in the latter case.
As regards the radio-nav sources (ILS, VOR, DME, ADF), there is no switching, neither automatic nor manual.
A. ARINC 429 Buses
(1) ADIRU-IR buses
The DMCs 1, 2 and 3 select for display the IR data from the ADIRU 1, 2 or 3 according to the logic given in the table below:
Note that the DMCs do not perform the automatic selection of another IR bus if the one normally used is no longer valid. It is up to the pilot to perform manual selection to another valid IR sensor.
Normally, the EIS DMC and/or ATT/HDG manual reconfiguration selections are made only when a DMC 1 or 2 and/or an ADIRU 1 or 2 are faulty.
However, they can be made also when those items of equipment operate properly.
In that case the DMCs select the IR according to the logic given in the above table.
The DMCs 1, 2 and 3 select for display the IR data from the ADIRU 1, 2 or 3 according to the logic given in the table below:
| ------------------------------------------------------------------------------- |
| !EIS DMC SELEC-!ATT/HDG SELEC-! DMC 1 ! DMC 2 ! DMC 3 ! |
| ! TOR SWITCH ! TOR SWITCH ! ! ! ! |
| !--------------!--------------!---------------!---------------!---------------! |
| ! NORM ! NORM ! IRS 1 ! IRS 2 ! IRS 1 ! |
| ! NORM ! CAPT/3 ! IRS 3 ! IRS 2 ! IRS 3 ! |
| ! NORM ! F/O/3 ! IRS 1 ! IRS 3 ! IRS 1 ! |
| ! CAPT/3 ! NORM ! IRS 1 ! IRS 2 ! IRS 1 ! |
| ! CAPT/3 ! CAPT/3 ! IRS 3 ! IRS 2 ! IRS 3 ! |
| ! CAPT/3 ! F/O/3 ! IRS 1 ! IRS 3 ! IRS 1 ! |
| ! F/O/3 ! NORM ! IRS 1 ! IRS 2 ! IRS 2 ! |
| ! F/O/3 ! CAPT/3 ! IRS 3 ! IRS 2 ! IRS 2 ! |
| ! F/O/3 ! F/O/3 ! IRS 1 ! IRS 3 ! IRS 3 ! |
| ------------------------------------------------------------------------------- |
Note that the DMCs do not perform the automatic selection of another IR bus if the one normally used is no longer valid. It is up to the pilot to perform manual selection to another valid IR sensor.
Normally, the EIS DMC and/or ATT/HDG manual reconfiguration selections are made only when a DMC 1 or 2 and/or an ADIRU 1 or 2 are faulty.
However, they can be made also when those items of equipment operate properly.
In that case the DMCs select the IR according to the logic given in the above table.
(2) ADIRU-ADR buses
The ADIRU ADR bus selection inside the DMCs follows exactly the same rules as the IR bus selection. Note that the IR and ADR manual reconfiguration selections are completely independent.
The ADIRU ADR bus selection inside the DMCs follows exactly the same rules as the IR bus selection. Note that the IR and ADR manual reconfiguration selections are completely independent.
(3) FAC buses
Each DMC receives the FAC 1 and 2 buses.
The FAC 1 or FAC 2 bus selection inside each DMC is automatic according to the logic given in the table below:
Note that a given FAC is considered as being invalid if its output bus is faulty (parameter not refreshed or in the F/W state), or if the FAC HEALTHY wired discrete signal is in the open circuit state.
Each DMC receives the FAC 1 and 2 buses.
The FAC 1 or FAC 2 bus selection inside each DMC is automatic according to the logic given in the table below:
| ------------------------------------------------------------------------------- |
| ! FAC 1 ! FAC 2 ! DMC ! DMC ! |
| ! VALID ! VALID ! SIDE 1 ! SIDE 2 ! |
| !-------!-------!------------------------------!------------------------------! |
| ! Y ! Y ! FAC 1 ! FAC 2 ! |
| !-------!-------!------------------------------!------------------------------! |
| ! Y ! N ! FAC 1 ! FAC 1 (*) ! |
| ! ! ! ! (message on ECAM) ! |
| !-------!-------!------------------------------!------------------------------! |
| ! N ! Y ! FAC 2 (*) ! FAC 2 ! |
| ! ! ! (message on ECAM) ! ! |
| !-------!-------!------------------------------!------------------------------! |
| ! N ! N ! FAC 1 <----> FAC 2 ! ! |
| ! ! ! permanent switching until ! ! |
| ! ! ! one valid FAC is found. ! ! |
| ! ! ! Meanwhile, SPD LIM red ! ! |
| ! ! ! message on CAPT PFD ! ! |
| ------------------------------------------------------------------------------- |
| (*) : Abnormal configuration. When a DMC works with an offside FAC and if |
| its onside FAC becomes valid again, the DMC works again with it. |
Note that a given FAC is considered as being invalid if its output bus is faulty (parameter not refreshed or in the F/W state), or if the FAC HEALTHY wired discrete signal is in the open circuit state.
(4) FMGC A bus (Guidance)
Each DMC receives and processes both FMGC 1 and 2 A buses. It uses them (either one or two) independently for the display of the flight director orders and the flight mode annunciations, according to the engagement status of the FDs and the APs.
Display of the FD or FPD orders :
The DMCs which work on side 1 use the FMGC 1-A bus for the display of the FD orders.
If FD 1 fails, or if the FMGC 1-A bus is no longer valid, there is an automatic switching and the DMC uses the FMGC 2-A bus for the display of the FD orders.
As regards the FMA, which displays the armed and active modes for the FD, the AP and the A/THR, the DMCs which work on side 1 use:
If the two FMGC A buses are invalid, at each cycle the DMC checks through the FMGC 1 and 2 A buses until a valid one is found. Meanwhile, the FD red message is displayed on the PFDs and the FMA is blanked.
Each DMC receives and processes both FMGC 1 and 2 A buses. It uses them (either one or two) independently for the display of the flight director orders and the flight mode annunciations, according to the engagement status of the FDs and the APs.
Display of the FD or FPD orders :
The DMCs which work on side 1 use the FMGC 1-A bus for the display of the FD orders.
If FD 1 fails, or if the FMGC 1-A bus is no longer valid, there is an automatic switching and the DMC uses the FMGC 2-A bus for the display of the FD orders.
NOTE: FD orders means : FD bars (pitch, roll, yaw) or FPD orders related to the Flight Path Vector in TK-FPA mode.
Display of the flight mode annunciations : As regards the FMA, which displays the armed and active modes for the FD, the AP and the A/THR, the DMCs which work on side 1 use:
- FMGC 1-A bus if no AP is engaged or if AP1 is engaged alone or if the two APs are engaged (DUAL)
- FMGC 2-A bus if AP2 is engaged alone, or if the FD2 orders are displayed (and the AP 1 is not engaged), which is the case when an automatic switching to the FD 2 has occurred.
If the two FMGC A buses are invalid, at each cycle the DMC checks through the FMGC 1 and 2 A buses until a valid one is found. Meanwhile, the FD red message is displayed on the PFDs and the FMA is blanked.
(5) FMGC EIS bus (Flight Management)
Each DMC receives the FMGC 1 and 2 EIS buses.
The DMCs which operate on side 1 work with FMGC 1 data, and the DMCs which operate on side 2 use the FMGC 2 data.
If one FMGC EIS bus is no longer valid, the DMC which normally uses its data automatically switches over to the EIS bus of the other FMGC. If the EIS bus of the first FMGC is again valid, the DMC reverts to it, but only after an action on the ND mode or scale selector switch of the FCU. If the two EIS buses are not valid, the DMC permanently switches from one to the other until a valid one is found.
Meanwhile, the amber message MAP NOT AVAIL is displayed on the NDs (if they are in ROSE/NAV or ARC or PLAN modes).
Each DMC receives the FMGC 1 and 2 EIS buses.
The DMCs which operate on side 1 work with FMGC 1 data, and the DMCs which operate on side 2 use the FMGC 2 data.
If one FMGC EIS bus is no longer valid, the DMC which normally uses its data automatically switches over to the EIS bus of the other FMGC. If the EIS bus of the first FMGC is again valid, the DMC reverts to it, but only after an action on the ND mode or scale selector switch of the FCU. If the two EIS buses are not valid, the DMC permanently switches from one to the other until a valid one is found.
Meanwhile, the amber message MAP NOT AVAIL is displayed on the NDs (if they are in ROSE/NAV or ARC or PLAN modes).
(a) The table below gives the bus selection logic concerning the FMGC EIS buses :
| ------------------------------------------------------------------------------- |
| ! FMGC 1 EIS ! FMGC 2 EIS ! DMC ! DMC ! |
| ! VALID ! VALID ! SIDE 1 ! SIDE 2 ! |
| !--------------!--------------!-----------------------!-----------------------! |
| ! Y ! Y ! FMGC 1 ! FMGC 2 ! |
| !--------------!--------------!-----------------------!-----------------------! |
| ! Y ! N ! FMGC 1 ! FMGC 1 ! |
| ! ! ! ! (message FMC 1 on F/O ! |
| ! ! ! ! ND) ! |
| !--------------!--------------!-----------------------!-----------------------! |
| ! N ! Y ! FMGC 2 ! FMGC 2 ! |
| ! ! ! (message FMC 2 on CAPT! ! |
| ! ! ! ND) ! ! |
| !--------------!--------------!-----------------------!-----------------------! |
| ! N ! N ! FMGC 1 <-------> FMGC 2 ! |
| ! ! ! Permanent switching until one valid FMGC is ! |
| ! ! ! found. Meanwhile, MAP NOT AVAIL message on ! |
| ! ! ! the NDs. ! |
| ------------------------------------------------------------------------------- |
(b) FMGC 1 or FMGC 2 EIS bus validity
A given FMGC EIS bus is considered as valid if :
A given FMGC EIS bus is considered as valid if :
- the corresponding FMGC HEALTHY discrete signal assumes the valid state
- and the EIS bus itself is recognized as valid.
NOTE: A given FMGC (eg 1) normally always works in the ND mode and in the range which are selected on the corresponding EFIS control section of the FCU.
NOTE: If a given FMGC EIS bus is invalid (FMGC failure or EIS bus not valid), the DMC which normally uses its parameters automatically switches over to the opposite FMGC EIS bus.
In this case, a SELECT OFFSIDE RANGE amber message pulses on the corresponding ND for 10 s.
Since an FMGC cannot produce 2 different ND images scaled on different ranges, the pilot who has lost his onside FMC should select the same range as the other pilot whose FMC still operates, in order to have identity between the range markers presented on his ND and those selected on his EFIS control section.
In this case, a SELECT OFFSIDE RANGE amber message pulses on the corresponding ND for 10 s.
Since an FMGC cannot produce 2 different ND images scaled on different ranges, the pilot who has lost his onside FMC should select the same range as the other pilot whose FMC still operates, in order to have identity between the range markers presented on his ND and those selected on his EFIS control section.
NOTE: If an FMGC receives no mode control and range selection (FCU failure for instance), it automatically produces an 80 NM indication on the ND.
(6) FCU buses
The FCU groups together all AFS and EIS selections and mode controls.
The FCU is a dual unit, fully redundant with 2 processors 1 and 2.
Normally, the processor 1 operates, and the processor 2 is a hot spare.
The FCU issues 4 ARINC 429 low speed buses : 1-A, 1-B, 2-A, 2-B.
In case of failure of the processor 1 of the FCU, the processor 2 takes over and all the DMCs receive the same data as those sent by the processor 1. This loss of redundancy is annunciated on the ECAM DUs (STATUS).
Briefly, the FCU bus X-A (1A and 2A) conveys the selections of the CAPT EFIS control section, plus some AFS selections.
The FCU bus X-B (1B and 2B) conveys the selections of the F/O EFIS control section, the remaining AFS selections, and both the CAPT and F/O baro reference settings.
The DMC(s) on side 1 uses the parameters from the buses 1-A and 1-B.
The DMC(s) on side 2 uses the parameters from the buses 2-A and 2-B.
The FCU groups together all AFS and EIS selections and mode controls.
The FCU is a dual unit, fully redundant with 2 processors 1 and 2.
Normally, the processor 1 operates, and the processor 2 is a hot spare.
The FCU issues 4 ARINC 429 low speed buses : 1-A, 1-B, 2-A, 2-B.
In case of failure of the processor 1 of the FCU, the processor 2 takes over and all the DMCs receive the same data as those sent by the processor 1. This loss of redundancy is annunciated on the ECAM DUs (STATUS).
Briefly, the FCU bus X-A (1A and 2A) conveys the selections of the CAPT EFIS control section, plus some AFS selections.
The FCU bus X-B (1B and 2B) conveys the selections of the F/O EFIS control section, the remaining AFS selections, and both the CAPT and F/O baro reference settings.
The DMC(s) on side 1 uses the parameters from the buses 1-A and 1-B.
The DMC(s) on side 2 uses the parameters from the buses 2-A and 2-B.
(7) ADF bus
Each DMC receives and processes the ADF receiver bus.
In case of failure of the ADF, the corresponding data are lost and a flag appears instead.
Each DMC receives and processes the ADF receiver bus.
In case of failure of the ADF, the corresponding data are lost and a flag appears instead.
(8) VOR buses
Each DMC receives and processes the VOR 1 and VOR 2 receiver buses.
There is no manual or automatic transfer VOR 1 - VOR 2 for failure cases. In the ND ROSE/VOR mode, the Captain always has the VOR 1 data and the First Officer the VOR 2 data, as regards the course and LATERAL deviation information. But each pilot can select VOR 1 and VOR 2 bearing and station identification data on his ND.
In case of failure of a given VOR, the corresponding data are lost and a flag appears instead.
Each DMC receives and processes the VOR 1 and VOR 2 receiver buses.
There is no manual or automatic transfer VOR 1 - VOR 2 for failure cases. In the ND ROSE/VOR mode, the Captain always has the VOR 1 data and the First Officer the VOR 2 data, as regards the course and LATERAL deviation information. But each pilot can select VOR 1 and VOR 2 bearing and station identification data on his ND.
In case of failure of a given VOR, the corresponding data are lost and a flag appears instead.
(9) DME
Each DMC receives and processes DME data from both DME interrogators.
DME 1 and DME 2 data can be displayed on each ND, but only the onside DME data can be displayed on a given PFD (e.g. DME 1 on the Captain PFD).
Each DMC receives and processes DME data from both DME interrogators.
DME 1 and DME 2 data can be displayed on each ND, but only the onside DME data can be displayed on a given PFD (e.g. DME 1 on the Captain PFD).
(10) ILS
Each DMC receives and processes the ILS data (LOC and GLIDE SLOPE deviation signals, ILS frequency, ILS IDENT, ILS COURSE) from both ILS receivers.
The ILS 1 data are displayed on the Captain PFD and the First Officer ND and the ILS 2 data on the First Officer PFD and the Captain ND.
No transfer is possible (ILS 1 - ILS 2), neither normal, nor automatic.
Each DMC receives and processes the ILS data (LOC and GLIDE SLOPE deviation signals, ILS frequency, ILS IDENT, ILS COURSE) from both ILS receivers.
The ILS 1 data are displayed on the Captain PFD and the First Officer ND and the ILS 2 data on the First Officer PFD and the Captain ND.
No transfer is possible (ILS 1 - ILS 2), neither normal, nor automatic.
(11) Radio altimeter
Each DMC receives and processes radio altitude data from both radio altimeter transceivers. The DMC on side 1 preferably uses the R/A 1 data, as long as the R/A 1 bus is valid.
If the R/A 1 bus is no longer valid, the DMC automatically uses the R/A 2 bus, but it reverts to the R/A 1 as soon as it becomes again valid.
If both R/A 1 and 2 buses are invalid, the DMC checks through the two buses at each cycle until a valid one is found.
Meanwhile, the red flag RA is displayed on the Captain PFD, only at low altitude (when slats are extended).
Each DMC receives and processes radio altitude data from both radio altimeter transceivers. The DMC on side 1 preferably uses the R/A 1 data, as long as the R/A 1 bus is valid.
If the R/A 1 bus is no longer valid, the DMC automatically uses the R/A 2 bus, but it reverts to the R/A 1 as soon as it becomes again valid.
If both R/A 1 and 2 buses are invalid, the DMC checks through the two buses at each cycle until a valid one is found.
Meanwhile, the red flag RA is displayed on the Captain PFD, only at low altitude (when slats are extended).
(12) SDAC
Each DMC receives and processes both SDAC 1 and 2 buses. The DMC on side 1 works in priority with SDAC 1 data.
The DMC preferably uses all the needed parameters from SDAC 1.
If one parameter is invalid, the DMC uses that from the SDAC 2.
If this parameter is available neither on the SDAC 1 bus, nor on the SDAC 2 bus, a flag is displayed on the affected A/C system image :
XXX if the parameter is a digital value.
If the parameter is a word of discretes, the corresponding parts of the image (synoptic lines or discrete elements such as pump or valve position) disappear.
The DMC(s) which works on side 2 follows the same rules, and also uses preferably the SDAC 1 data.
Each DMC receives and processes both SDAC 1 and 2 buses. The DMC on side 1 works in priority with SDAC 1 data.
The DMC preferably uses all the needed parameters from SDAC 1.
If one parameter is invalid, the DMC uses that from the SDAC 2.
If this parameter is available neither on the SDAC 1 bus, nor on the SDAC 2 bus, a flag is displayed on the affected A/C system image :
XXX if the parameter is a digital value.
If the parameter is a word of discretes, the corresponding parts of the image (synoptic lines or discrete elements such as pump or valve position) disappear.
The DMC(s) which works on side 2 follows the same rules, and also uses preferably the SDAC 1 data.
(13) FWC data buses (not RS - 422)
The FWC 1 and 2 data buses also convey data for A/C system images or for further retransmission by the DMC.
The logic for the parameter choice obeys exactly the same rules as for the SDAC.
The FWC 1 and 2 data buses also convey data for A/C system images or for further retransmission by the DMC.
The logic for the parameter choice obeys exactly the same rules as for the SDAC.
(14) ECU (FADEC system)
Each Engine Control Unit issues 4 output buses, which always convey the same data 2 by 2 (A1 & A2, B1 & B2).
Each ECU is fully redundant : in case of failure of channel A, channel B takes over.
Each DMC receives and processes one A bus and one B bus from each engine ECU.
The DMCs take the needed parameters preferably on the bus corresponding to the channel in control (word 275, bit 26 = CHANNEL A IN CONTROL, word 275, bit 27 = CHANNEL B IN CONTROL).
If a parameter is invalid on one bus, the DMC takes it on the other bus. If this parameter is available neither on the A bus, nor on the B bus, the corresponding indication is either flagged (XX) or removed, depending on the nature of the parameter.
Each Engine Control Unit issues 4 output buses, which always convey the same data 2 by 2 (A1 & A2, B1 & B2).
Each ECU is fully redundant : in case of failure of channel A, channel B takes over.
Each DMC receives and processes one A bus and one B bus from each engine ECU.
The DMCs take the needed parameters preferably on the bus corresponding to the channel in control (word 275, bit 26 = CHANNEL A IN CONTROL, word 275, bit 27 = CHANNEL B IN CONTROL).
If a parameter is invalid on one bus, the DMC takes it on the other bus. If this parameter is available neither on the A bus, nor on the B bus, the corresponding indication is either flagged (XX) or removed, depending on the nature of the parameter.
(15) FQI
The FQI issues four buses, FQI-1A, 1B, 2A, 2B.
DMC 1 acquires 1A and 2A.
DMC 3 acquires 1A and 2B.
DMC 2 acquires 1B and 2B.
Each DMC preferably uses the FQI-1 (A or B) bus parameters.
If the FQI CHANNEL SUPERIORITY signal (bit 13 of word 276) requests the switching to the FQI-2 bus, the DMCs switch to this FQI-2 bus.
However the DMC keeps using a given FQI-X bus only if this bus is valid.
If the two FQI-1 and 2 buses are invalid, the DMC permanently switches from one to the other until a valid one is found. Meanwhile, the fuel quantity parameters are flagged (XX) on the ECAM E/W image.
TCAS
Each DMC receives and processes TCAS data. The NDs indicate the position of intruders in the airspace in ROSE or ARC mode. The PFDs provide the crew with vertical speed indications to avoid these intruders.
The Flight Warning Computers (FWC) ensure the monitoring and the validity of these data.
If one part of the TCAS is faulty, a message is displayed on the engine page of the upper ECAM display unit.
The FQI issues four buses, FQI-1A, 1B, 2A, 2B.
DMC 1 acquires 1A and 2A.
DMC 3 acquires 1A and 2B.
DMC 2 acquires 1B and 2B.
Each DMC preferably uses the FQI-1 (A or B) bus parameters.
If the FQI CHANNEL SUPERIORITY signal (bit 13 of word 276) requests the switching to the FQI-2 bus, the DMCs switch to this FQI-2 bus.
However the DMC keeps using a given FQI-X bus only if this bus is valid.
If the two FQI-1 and 2 buses are invalid, the DMC permanently switches from one to the other until a valid one is found. Meanwhile, the fuel quantity parameters are flagged (XX) on the ECAM E/W image.
TCAS
Each DMC receives and processes TCAS data. The NDs indicate the position of intruders in the airspace in ROSE or ARC mode. The PFDs provide the crew with vertical speed indications to avoid these intruders.
The Flight Warning Computers (FWC) ensure the monitoring and the validity of these data.
If one part of the TCAS is faulty, a message is displayed on the engine page of the upper ECAM display unit.
B. FWC Message Bus (RS 422)
Inside each DMC, the principle of selection of the FWC 1 or FWC 2 message bus obeys the same rules as for the ARINC 429 bus. Each DMC preferably works with the FWC 1 RS-422 bus. In case of detected failure, it automatically switches to the FWC 2 RS-422 bus.
A given FWC RS-422 bus is considered as valid if :
- each block is complete : detection of the start of block (Soh code for E/W blocks, Stx for S blocks) and of the end of block (Etb code for E/W blocks, Eot for S blocks)
- the number of characters which are received by the DMC matches the number of characters which are transmitted. This number is given in the 3-digit number which follows the end of block code (the 3 characters of the 3-digit number are included in the total number of characters which are transmitted)
- each character is valid : for the characters, a parity check is made.
If a character is not valid, the block is considered as invalid if the failure is confirmed during 3 successive transmissions
Inside each DMC, the principle of selection of the FWC 1 or FWC 2 message bus obeys the same rules as for the ARINC 429 bus. Each DMC preferably works with the FWC 1 RS-422 bus. In case of detected failure, it automatically switches to the FWC 2 RS-422 bus.
A given FWC RS-422 bus is considered as valid if :
- each block is complete : detection of the start of block (Soh code for E/W blocks, Stx for S blocks) and of the end of block (Etb code for E/W blocks, Eot for S blocks)
- the number of characters which are received by the DMC matches the number of characters which are transmitted. This number is given in the 3-digit number which follows the end of block code (the 3 characters of the 3-digit number are included in the total number of characters which are transmitted)
- each character is valid : for the characters, a parity check is made.
If a character is not valid, the block is considered as invalid if the failure is confirmed during 3 successive transmissions
- the time between two successive blocks of the same nature does not exceed 1.5 s.
C. Weather Radar Buses (ARINC 453)
A Weather Radar equipment which complies with ARINC 708-4 is installed.
Each DMC receives from the W/R transceivers units their two data buses, D1 and D2.
The DMC processes information from the operating W/R transceiver (only one at a time according to the position of the 1-2 selection switch on the W/R control unit and provided that W/R operation is enabled by the W/R request control signal).
Provided that the W/R operation is requested on the W/R control unit, the ND presents a W/R image in all the ND modes except the PLAN mode. If both pilots select the PLAN mode, the DMCs send the W/R REQUEST discrete signal in the open state, which disables the W/R XCVR. This avoids useless operating hours.
Data bus selection :
The DMCs which operate on side 1 normally work with the DATA 1 buses (XCVR 1-1 or XCVR 2-1), which correspond to the CAPT range selection.
However, the DMCs which operate on side 1 may operate with a DATA 2 bus, i.e. using the data corresponding to the range selected by the F/O, in case of an FMGC 1 failure which leads to an automatic changeover to the FMGC 2 data in the DMC 1.
In this case, the DMC 1 (or DMC 3 if the EIS DMC selector switch is set to CAPT/3) processes the DATA 2 bus from the W/R XCVR in operation.
The range markers and the mode on the Captain ND are then those corresponding to the F/O selection, which is indicated on the Captain ND by an amber message : SELECT OFFSIDE RANGE & MODE. This message may disappear sooner, if the Captain selects the same range as the First Officer. The same applies for the DMCs working on side 2, which normally use the D2 buses, but which use the D1 buses in case of FMGC 2 failure.
A Weather Radar equipment which complies with ARINC 708-4 is installed.
Each DMC receives from the W/R transceivers units their two data buses, D1 and D2.
The DMC processes information from the operating W/R transceiver (only one at a time according to the position of the 1-2 selection switch on the W/R control unit and provided that W/R operation is enabled by the W/R request control signal).
Provided that the W/R operation is requested on the W/R control unit, the ND presents a W/R image in all the ND modes except the PLAN mode. If both pilots select the PLAN mode, the DMCs send the W/R REQUEST discrete signal in the open state, which disables the W/R XCVR. This avoids useless operating hours.
Data bus selection :
The DMCs which operate on side 1 normally work with the DATA 1 buses (XCVR 1-1 or XCVR 2-1), which correspond to the CAPT range selection.
However, the DMCs which operate on side 1 may operate with a DATA 2 bus, i.e. using the data corresponding to the range selected by the F/O, in case of an FMGC 1 failure which leads to an automatic changeover to the FMGC 2 data in the DMC 1.
In this case, the DMC 1 (or DMC 3 if the EIS DMC selector switch is set to CAPT/3) processes the DATA 2 bus from the W/R XCVR in operation.
The range markers and the mode on the Captain ND are then those corresponding to the F/O selection, which is indicated on the Captain ND by an amber message : SELECT OFFSIDE RANGE & MODE. This message may disappear sooner, if the Captain selects the same range as the First Officer. The same applies for the DMCs working on side 2, which normally use the D2 buses, but which use the D1 buses in case of FMGC 2 failure.
NOTE: The W/R equipment has different buses, D1 being associated to the CAPT range, and D2 to the F/O range.
NOTE: If there is a discrepancy between the range selection from the FCU and the range selection sent on the corresponding W/R data bus, no W/R image is displayed and the W/R RANGE red message is displayed.