W DOC AIRBUS | AMM A320F

FAULT ISOLATION FUNCTION - PRINCIPLE - DESCRIPTION AND OPERATION

** ON A/C NOT FOR ALL
1. General
A. Line Maintenance
The line maintenance of the Automatic Flight System (AFS) is based on the use of the Fault Isolation and Detection System (FIDS).
The system:
  • detects, isolates and stores the AFS internal and external faults,
  • initiates and performs the test after replacement of an AFS LRU,
  • initiates and performs the availability test of the category III automatic landing function.
B. Characteristics of the AFS Maintenance System
A certain number of the AFS maintenance system characteristics are common to all the aircraft systems. These characteristics are described in ATA Ref. 31-32-00 Centralized Fault Display Interface (CFDIU) and concern:
  • The built-in test equipment (BITE) operating principle:
    . Transmission of fault messages in normal mode
    . Transmission of maintenance data in menu mode
  • The operational use of the multipurpose control and display unit (MCDU) up to access to the AFS REPORT/TEST page.
C. Safety
Special precautions were taken at the maintenance system design stage to ensure safety:
(1) at test level (LAND TEST, AFS TEST).
Each test request made via the MCDU is accepted only if certain conditions concerning the components which perform the test are met:
  • FIDS : The FIDS will only accept the test request if its ground condition is met (NOSE GEAR PRESSED).
  • LRUs UNDER TEST : The LRUs under test will only accept the test request if their own ground conditions are met (NOSE GEAR PRESSED AND ENGINES STOPPED).
(2) The BITE and TEST software is only allowed to read the variables of the operational software.
** ON A/C NOT FOR ALL
2. Component Location
F Component Location
FIN FUNCTIONAL
DESIGNATION		 PANEL ZONE ACCESS
DOOR		 ATA REF
** ON A/C ALL
1CA1 FMGC-1 824 127 22-83-34
1CA2 FMGC-2 84VU 128 22-83-34
2CA FCU 13VU 210 22-81-12
3CA1 MCDU-1 11VU 210 22-82-12
3CA2 MCDU-2 11VU 210 22-82-12
1CC1 FAC-1 83VU 127 22-66-34
1CC2 FAC-2 84VU 128 22-66-34
** ON A/C NOT FOR ALL
3CA3 MCDU-3 101VU 211 22-82-12
** ON A/C NOT FOR ALL
3. System Description
A. General
The system comprises:
  • A FIDS card physically located in each Flight Augmentation Computer (FAC), only the card located in the FAC1 is activated (by the SIDE 1 signal)
  • The BITEs located in these various AFS computers:
    . Flight Management and Guidance Computers (FMGCs 1 and 2) (COM, MON, FM)
    . FACs 1 and 2 (COM, MON)
    . Flight Control Unit (Channels 1 and 2)
    . MCDUs 1 and 2.
B. Description
F Functional Block Diagram
(1) FIDS card:
The FIDS card includes:
  • a CPU (Microprocessor and associated circuits),
  • a memory module containing the application program,
  • ARINC input/output circuits,
  • discrete input/output circuits.
The FIDS serves as the SYSTEM BITE (maintenance data concentrator).
The FIDS is linked in acquisition and reception to the centralized fault-display interface-unit (CFDIU) and is connected to the BITEs of the various AFS computers.
It receives commands from the CFDIU, interprets these commands and transfers them, if applicable, to the various BITEs concerned.
It receives malfunction reports from the BITEs, manages these reports, and, if applicable, consolidates the BITE diagnosis and generates a fault message which is sent to the CFDIU.
(2) AFS BITE
  • The BITE is an electronic device (HARDWARE + SOFTWARE) located inside each AFS computer.
  • Its main function is to detect, isolate and store the system failures in the non-volatile memories.
  • There are different AFS BITE architectures:
    * COM/MON with two level of analysis: FAC and FG
    * single computer with one level of analysis: FM
    * peripheral not linked to FIDS, monitored through corresponding computer: FCU (FG), MCDU (FM)
    * FIDS which is monitored by the AFS computers (FAC/FG) and CFDS.
C. FIDS operation
The system has two fault detection and isolation modes:
  • Normal mode (flight) :
    The system stores the failure data relevant to the AFS in non-volatile memories and transmits these data to the CFDIU.
  • Menu mode (ground):
    The system transmits a menu to the MCDU via the CFDIU.
(1) Normal mode
In normal mode, the AFS maintenance system ensures the following functions:
  • Fault detection
    The fault is detected at the level of each computer BITE by constant monitoring of specific variables of the operational software.
  • Fault isolation
    The detection of a fault triggers an analytic process. This process identifies the LRU from which the fault originates. This analysis is performed in two steps:
    1st step: A first analysis is made at the level of the computer which detected the fault.
    This first step can itself be split into two phases at FAC and FG level (1st and 2nd phase analysis).
    2nd step: A second analysis is made at FIDS level. This analysis is called the 3rd phase analysis.
  • Storage of faults in the non-volatile memories.

The breakdown of these functions is shown on figures:
F Fault Detection - 1st and 2nd Phase Analysis
F 3rd Phase Analysis (Update of CD)
To perform the functions described above, the system consecutively performs the following operations:
  • Interpretation and execution of the CFDIU commands by the FIDS.
  • Interpretation and execution of the FIDS commands by the FAC, FG and FM BITEs.
  • Fault detection at the level of each AFS BITE.
  • Transmission of maintenance data by the FCU BITE to the FG and by the MCDU BITE to the FM.
  • Fault isolation, creation of fault contexts and memorization of these contexts by the FAC, FG and FM BITEs.
  • Transmission of the malfunction reports of the BITEs to the FIDS.
  • Management and consolidation of the malfunction reports by the FIDS.
  • Generation of a fault message from this consolidated diagnosis, which is sent to the CFDIU.
  • Memorization of faults by the FIDS.
(a) Interpretation and execution of the CFDIU commands by the FIDS
1 The FIDS card, connected to the CFDIU in acquisition, receives from the CFDIU:
  • A control word
  • Various information:
    * DATE
    * UTC (Universal Time Coordinated)
    * Aircraft identification
    * Flight phase
2 Use of DATE, UTC and AIRCRAFT IDENTIFICATION and FLIGHT PHASE informations. These informations are received by the FIDS from the CFDIU.
NOTE: If the DATE and UTC informations are not available, the FIDS will send out for these datas:
  • DATE: /3F
  • UTC: 3FHFF
  • The DATE and UTC informations are transmitted by the FIDS to the FAC, FG and FM BITES in order to enhance their fault contexts.
  • The AIRCRAFT IDENTIFICATION information is used by the FIDS for the LRU IDENTIFICATION option (Ref. Menu Mode)
  • The FLIGHT PHASE information is used at two levels:
    * It is transmitted to the FAC, FG and FM BITEs by means of the command. These BITEs use this information to manage the memory areas where the fault contexts are stored (ground area, flight area).
    * It is used by the FIDS which, during detection of flight phase change, activates a consolidation process for the fault diagnosis sent by the BITEs (Ref. 3rd phase analysis).
3 Emergency operation in case of CFDIU failure or absence
  • The FIDS detects CFDIU failure or absence by detecting non-refresh of the control word.
  • In this case, it uses for operation the GROUND/FLIGHT information given by the wired discrete NOSE GEAR PRESD which it receives directly:
    * on the ground : the FIDS sends a command to the BITEs requesting them not to record any more internal or external faults.
    * in flight : the FIDS sends the command DC1 to the BITEs (Ref. previous table).
(b) Interpretation and execution of the FIDS commands by the FAC, FG and FM BITEs
1 Each BITE
FAC 1 COM
FAC 1 MON
FAC 2 COM
FAC 2 MON
FG1 COM
FG1 MON
FG2 COM
FG2 MON
FM1
FM2
receives from the FIDS: - a control word
- Date, UTC.

2 Interpretation and execution of the commands in the ground or flight area
Each BITE stores a certain quantity of fault information (Ref. fault context) in the non-volatile memories.
These memories are split into several areas:
  • Ground area: this area is capable of storing 3 faults and their context. It is cleared at each ground/flight transition.
  • Flight area: this area is capable of storing 30 faults and their context.
When the memories are full, the first-in fault is eliminated first.
Each BITE executes these FIDS commands:
  • No fault recording
  • Fault recording in ground area
  • Fault recording in flight area
  • Fault confirmation request (Ref. 3rd phase analysis)
  • Triggering variable re-initialization request (Ref. Fault Detection).
3 Use of DATE and UTC information
This information is used by the BITEs to enhance their fault contexts.
4 Emergency operation in case of inoperative FIDS.
  • The BITEs detect absence or failure of the FIDS by detecting non-refresh of the control labels.
  • In this case, each BITE operates by using the ground/flight information given by the wired discrete NOSE GEAR PRESD which each FAC and FMGC receives directly.
    * on the ground : BITEs do not record faults.
    * in flight : BITEs record faults in flight area.
(c) Fault detection at each BITE of the AFS
1 FAC, FG and FM BITEs
  • Event trigger
    A triggering event detected by the BITE function of a computer corresponds to a change in state of a functional variable of the application software of this computer.
    This event triggers a fault isolation and storage process.
    In order not to report to the CFDIU too many transitory events which have no cockpit effect, the status change of each monitored variable must have a duration greater than a predetermined failure confirmation time.

    Re-initialization purpose :
    In order to allow failure storage after CFDS phase change when the monitoring is extended (for example when changing from ground scanning to flight one, the AFS external failures must start to be monitored), the triggering variable detection within each BITE is reinitialised upon FIDS request. This allows to detect a failure already present before a phase change.

    F Fault Detection
  • Hierarchical configuration of the triggering events (only for FAC and FG)
    In order to trigger the fault isolation process, the BITE permanently scans a certain number of functional variables. These variables are hierarchically configured in order to take into account only the event with highest priority in the application software functional sense, i.e. the event whose appearance may cause other events.
2 MCDU BITE
The MCDU performs the following tests:
  • Processor test,
  • RAM test,
  • EPROM test,
  • EEPROM test,
  • Video monitoring,
  • Background monitoring.
The RDY annunciator comes on (green) when the MCDU passes its long-term power-up or power-off reset test, after its BRT knob is turned to OFF.
If a failure is found, the FAIL annunciator comes on and the MCDU FAIL discrete output is set from ground to open circuit.
3 FCU BITE
The FCU BITE continuously computes the maintenance status of both FCU channels.
Consequently, the essential information is crossed between the FCU channel 1 and the FCU channel 2. The results of this monitoring are loaded in the BITE memory.
(d) Transmission of maintenance data by the MCDU and FCU BITE
1 MCDU
The MCDU continuously sends to the FM an MCDU HLTY discrete signal relevant to its state.
2 FCU
The FCU continuously sends to the FG a maintenance label and an FCU HLTY discrete signal both relevant to its state.
(e) Fault isolation at FAC, FG and FM BITE level
When a fault is detected, the system consecutively performs the following operations:
  • Takes the snapshot and performs acquisition of the MCDU and FCU maintenance data
  • Analyzes
    Fault isolation is performed first at the level of the FAC, FG and FM BITEs then at FIDS level.
    For isolation, these BITEs use the snapshots for internal variables and also use for the MCDU and FCU the maintenance words received respectively by FM and FG.
1 FAC, FG and FM snapshots
  • The snapshot contains the state (0 or 1) of a certain number of application software functional variables (a maximum of 76).
  • Each time a trigger event is detected, a snapshot is taken.
  • The snapshot is specific to the triggering event.
  • The snapshot contains the data enabling the system to analyze the fault and isolate the faulty LRU(s).
  • Snapshots are displayed within TSD (trouble shooting data) in menu mode (words W1 to W5).
2 The information transmitted by the FCU and the MCDU is considered by the FG and FM BITEs as ordinary snapshots.
3 Analysis
F Fault Detection - 1st and 2nd Phase Analysis
4 Analysis (FAC, FG (COMMAND and MONITOR), and FM BITE levels)
a 1 st phase analysis
F 1st Phase Analysis - FAC, FG and FM BITE levels
The 1st phase analysis is made by the side of the computer which detected the triggering event.
The result of this analysis is named RESANAC (result of analysis in COM lane) or RESANAM (result of analysis in MON lane).
Composition is as follows:
-----------------------------------------------------------------
! ! ! !
! TYPE / SYMETRY CODE ! ERROR CODE ! EVENT !
! ! ! !
-----------------------------------------------------------------

  • Event: triggering event
  • Error code: calculated from the state of the variables of the snapshot and, if applicable, the maintenance word transmitted by the FCU.
  • Type/symetry code
    Type: Area where fault context is recorded (ground, flight, AFS TEST, LAND TEST).
    Symetry: coded to 1 when the failure must be symmetrical i.e. detected by both sides of the computer. In this case, an additional analysis is made at the computer command side (2nd phase analysis).
    The RESANAM is transmitted to the COMMAND side if the fault was detected on the MONITOR side (not available for FM BITE analysis).
b 2nd phase analysis (not available for FM BITE analysis)
The second phase analysis is made by the COMMAND side of the computer following a triggering event. It is triggered on reception of a RESANAC or a RESANAM.
The 2nd phase analysis computes:
  • A RESANA (result of analysis of the second phase in lane COM) which has the same composition as the RESANAC or the RESANAM and is displayed within TSD in menu mode (C/M result of analysis).
  • Two codes, CLRU1 and CLRU2, which designate two LRUs suspected as being the origin of the analyzed fault.
    CLRU1 is allocated to the LRU with the higher probability of failure.

The general computation principle is as follows:
  • The 2nd phase analysis is only performed if RESANA C or M, computed by the 1st phase analysis, comprises a bit S coded to 1 (Ref. RESANA composition).
  • If this analysis is effective, a 2 second correlation window is opened to take into account, if applicable, the result of the 1st phase analysis transmitted by the other part of the computer.
    If the fault is correlated, bit CD=0, the 3rd phase analysis will not be made at FIDS level (CD = Correlation Demand).
    If not, bit CD=1 when fault isolation cannot be performed at the level of the computer which detected the fault, then an additional analysis is made at FIDS level (3rd phase analysis).
  • The LRU failure codes are computed from RESANA or RESANAC and RESANAM.
(f) Creation and save of the fault context in the BITE memories
  • Composition of the fault context:
    -------------------------------------------------------------------------------
    ! NFIDS ! NLRU !
    !-----------------------------------------------------------------------------!
    ! FLIGHT LEG !
    !-----------------------------------------------------------------------------!
    ! UTC !
    !-----------------------------------------------------------------------------!
    ! DATE !
    !-----------------------------------------------------------------------------!
    ! RESANA !
    !-----------------------------------------------------------------------------!
    ! RESANAC (not available for FM BITE) !
    !-----------------------------------------------------------------------------!
    ! RESANAM (not available for FM BITE) !
    !-----------------------------------------------------------------------------!
    ! SNAPSHOT (80 variables displayed in five 16-bit words: W1, W2, W3, W4, W5) !
    -------------------------------------------------------------------------------

    * NFIDS: Number generated by the FIDS to manage the fault context
    * NLRU: Fault number
    * FLIGHT LEG
    * UTC
    * DATE
    * RESANA: filled in from COMMAND side only
    * RESANAC: filled in from COMMAND side only
    * RESANAM: filled in from MONITOR side and recopied on COMMAND side
    * Snapshot
  • Make-up of the fault context
    * All information, except for NFIDS, making up the fault context is stored in the context at the end of the analysis at BITE level.
    * As the NFIDS is generated by the FIDS, this fault context area is only filled in after reception, by the FIDS, of a malfunction report sent by the COMMAND side of the FAC or the FG, which detected the failure, or by the FM.
    * For the FM, RESANAC and RESANAM areas do not exist.
  • Save of fault context.
    This context is saved in the non-volatile memories.
(g) Creation and transmission of the anomaly report
* At the end of the analysis, a malfunction report is sent to the FIDS by the computer which detected the fault.
* This malfunction report is composed of the RESANA (C/M result of analysis within TSD) and the two LRU codes (described above) corresponding to the suspected LRUs.
------------------------------------------------------
! !
! RESANA !
! !
!-----------------------!----------------------------!
! LRU 2 CODE ! LRU 1 CODE !
------------------------------------------------------

(h) Management of the malfunction reports by the FIDS
1 On reception of a malfunction report, the FIDS generates and sends, to the BITE of the computer which recorded the fault, either a clearing command if the failure occurs within a phase in which the storage of the failure is not required, or an NFIDS management number. This number will be used to retreive the fault. The FIDS then records this malfunction report in the non-volatile memories.
2 Management of identical malfunction reports:
  • 2 malfunction reports are considered as identical when the following three conditions are met:
    . their two error code areas are identical
    . they come from the same computer
    . they occurred during the same flight.
    In this case, only the first malfunction report received by the FIDS is recorded and each time a new identical malfunction report is received, an event counter, linked to the recorded report, is incremented (from 1 to 4).
    F 3rd Phase Analysis (Update of CD)
(i) Consolidation of the malfunction reports by the FIDS, 3rd phase analysis
1 The FIDS sends to the CFDIU a message comprising:
  • an initial word including the following information:
    . OF (Origin of the Failure): set to 1 when the fault is internal to the AFS system
    . FW (Failure Witness): set to 1 as long as fault is present
    . CFF (Current Fault Flag): set to 1 as long as the system is affected by at least one internal or external fault
    . BHF (BITE History Flag): Set to 1 as soon as the BITE memory is loaded by the detection of an internal or external failure on the last 63 flights.
  • a text of 30 characters making up the fault message displayed on the MCDU.
2 The FIDS consolidates the malfunction reports of the various BITEs during the 3rd phase analysis, and generates the various information which make up the fault messages.
3 General principle of the 3rd phase analysis:
  • Update of Failure Witness (FW)
    FW allows the FIDS to correlate present faults between two computers when one has obtained a non-coherent result of analysis between COM and MON (second phase of analysis).
    This analysis is triggered at each flight phase change.
    When the malfunction is recorded in the FIDS, FW is set to 1.
    For each malfunction report recorded with FW = 1, the FIDS in 3rd phase analysis mode interrogates the BITE which sent the malfunction to know if the malfunction which initiated the taking of the snapshot is still present.
    If yes, FW remains at 1, if not FW is set to 0.
    When the source of the malfunction has disappeared, the BITE is again authorized to take a new snapshot.
    Reappearance of the malfunction causes transmission of a malfunction report identical to the one recorded in the FIDS, and forces relevant FW to 1.
    This analysis permits to update the OCCURRENCE OF THE FAILURE information.
    When the failure is not present at last-flight phase change, the FIDS adds the RTOK (RETEST OK) text at the end of the message.
    At each area change, the FIDS sends a command of triggering variable re-initialization to the BITEs. In this case, the failure is dated (UTC
  • Update of Correlation Demand (CD)
    CD is a request from dual lane BITE (FAC/FG) emitted when the second phase result of analysis is not coherent between COM and MON lanes (symetric fault not seen).
    This analysis is triggered at each reception of a new fault report with CD = 1 by the FIDS.
    For a given malfunction report, CD is normally given by the 2nd phase analysis in the computer and accompanies the error code.
    For each malfunction report (RA) received with FW = 1 and CD = 1, the FIDS, in 3rd phase analysis mode, interrogates its context table in order to correlate this malfunction report:
    . with another malfunction report
    . with FW = 1, CD = 0 and indicating same faulty LRU.
    If correlation is possible, CD of RAa changes to 0.
    If correlation is negative, RAa is checked to see if it has declared another LRU as faulty under second probability. If this is the case, a correlation is made as described above. If correlation is possible, CD of RAa changes to 0 and the LRU concerned becomes the first probable cause of failure. If not, CD remains at 1.
  • Update of OF: set when 3rd phase analysis has diagnosed an internal or external LRU failure.
  • Update of CFF and BHF: these items of information are set by the 3rd phase analysis in accordance with the presence or not of at least 1 failure detected by the system on the current flight or previous flights.
  • Generation of failure text:
    The 3rd phase analysis computes two error codes, CLRU1 and CLRU2, corresponding to the two LRUs suspected as being the origin of the analyzed failure. The codes are planted in decreasing failure probability order.
    The final fault message is generated from the LRU code with highest failure probability.
(j) Memorization of failures by FIDS
For a given failure, the FIDS memorizes the following information:
  • NFIDS
  • Fault message
  • RESANA, RESANAC and RESANAM
  • DATE
  • UTC
  • OCCURRENCE OF THE FAILURE
  • FAIL NUMBER (FAIL NO)
    Part of this information is displayed on the MCDU in menu mode.
(2) Menu Mode
(a) General
1 The menu mode is relevant to a specific operation enabled only on the ground. It is based on an interactive dialogue between the FIDS and the MCDU.
As the principle of this dialogue is common to all the systems which dialogue with the MCDU, it will not be described in detail in this document. For further details, refer to ATA Ref 31-32-00 (Menu mode and pseudo-menu mode).
The functions of the system in menu mode are:
  • Generation of pages:
    . MAIN MENU
    . LAST LEG REPORT
    . PREVIOUS LEG REPORT
    . TROUBLE SHOOTING DATA
    . GROUND SCAN
    . LRU IDENTIFICATION
    . LAND TEST
    . AFS TEST
    . WINDSHEAR TEST (if windshear function activated).
  • Execution of the various options described previously.
2 Operation: access to main menu, chaining of the various pages are described in para G. All the pages presented by the MCDU are generated by the FIDS.
(b) Main menu
F AFS - MAIN MENU Page
1 The MAIN MENU page is shown on figure. It gives the various options available in menu mode.
(c) Description of Main Menu option operation
1 LAST LEG REPORT
F LAST LEG and PREVIOUS LEG REPORTS/TSD Pages
  • This function gives on the ground only, the internal and external failure messages recorded during the last flight.
  • Information presented:
    . FLIGHT LEG: The FLIGHT LEG number is always at blank for failures relevant to last flight
    . DATE, UTC when failure was detected or taken into account
    . FAULT REPORT: fault message (identical to the message transmitted in normal mode)
    . ATA: ATA reference of LRU given as faulty
    . ISSUED BY: computer which originated the Fault message (e.g. : FAC1C, FAC2C/M, etc.)
    . FAIL NO: Number of presented fault. This counter is reset at the start of each flight phase. The first fault presented is the fault which occurred last during the last flight.
    . OCCURENCE: Number of times when the same failure occurs.
  • Access to the following failure is made by pushing the NEXT PAGE key on the MCDU
  • In addition, one of the main menu options:
    TROUBLESHOOTING DATA is directly accessible from this function.
2 PREVIOUS LEG REPORT
F LAST LEG and PREVIOUS LEG REPORTS/TSD Pages
  • This function presents, on the ground only, the internal and external fault messages which appeared during the 64 previous flights. This memo is the sum of the LAST LEG REPORT memos of several flights.
  • Information presented
    The information presented is identical to that presented in the LAST LEG REPORT except that:
    FLIGHT LEG: The counter is incremented at each ground/ flight changeover.
    FAIL NO: Fault number presented for a given FLIGHT LEG.
  • The first fault presented corresponds to the last fault which occurred during the previous flights.
3 TROUBLESHOOTING DATA
F LAST LEG and PREVIOUS LEG REPORTS/TSD Pages
  • This function presents, on the ground only, additional information relevant to the faults.
    This page is established from the fault context recorded in the BITE non-volatile memories:
    . DATE, UTC, Flight Leg
    . COM (RESANAC), MON (RESANAM) and C/M (RESANA)
    . Snapshot data (W1, W2, W3, W4 and W5)
  • This function can be accessed from two levels:
a From the main menu:
  • On selection of the TROUBLE SHOOTING DATA option, the FIDS generates a page for selecting the BITE that the operator wishes to examine.
  • When the BITE has been selected, the FIDS presents the content of the memories of this BITE starting by the most recent fault. The following faults are accessible by pushing the NEXT PAGE key on the MCDU.
b From the LAST LEG REPORT, PREVIOUS LEG REPORT, GROUND SCAN, LAND TEST and AFS TEST options:
On selection of the TROUBLE SHOOTING DATA option, the FIDS directly presents the context of the fault which is being displayed.
4 GROUND SCAN
F MCDU Pages MAIN MENU and Ground Scan Options
  • Access to the GROUND SCAN function
    This function is accessible from the MCDU when the system is in menu mode (when the aircraft is on the ground).
    The following three functions can be accessed when the AFS /GROUND SCAN page is displayed:
    - GROUND REPORT
    - PRESENT FAILURES SCAN
    - PROGRAM (if active).
    The line key adjacent to the RETURN indication enables selection of the previous menu page.
  • GROUND REPORT function
    This function enables the failures recorded in the ground area of the FIDS memory to be displayed.
    As this memory is capable of storing three contexts, the three most recent failures can be displayed, the oldest contexts being eliminated.
    The content of the ground area is erased during computer power up and engine start (NULL to DC2).
    The failures memorized and visible in the GROUND REPORT are the ones which occurred after the last ground area initialization.
    Two types of content can be displayed:
    * Only the internal failures that occured on ground are normally displayed by the GROUND REPORT function.
    * After selection of the PRESENT FAILURES SCAN function (Ref. para. PRESENT FAILURES SCAN function) all internal and external failures (considering a limit of three contexts) found during this operation are seen in this report. As selection of the PRESENT FAILURES SCAN function erases the content of the ground area, it is highly recommended, prior to this selection, to display this content using the GROUND REPORT function.
    Failures are presented with the following data:
    - the flight counter (-00) which indicates that the failure occurred on the ground
    - the ATA reference and associated message
    - the computer which identified the failure.
    Additional information can be obtained by selecting the TROUBLE SHOOTING DATA item (push action on the line key adjacent to the TROUBLE SHOOTING DATA indication). The procedure and the displayed content are similar to the LAST LEG REPORT and PREVIOUS LEGS REPORT.
  • PRESENT FAILURES SCAN function
    (GROUND SCANNING)
    This function is used to isolate failures present when the function is selected. Therefore an inhibited failure will not be announced. Once the function is activated (push action on the line key adjacent to the PRESENT FAILURES SCAN indication), a wait message is displayed for 40s while the system isolates the present failures.
    After this time, the messages are displayed on the GROUND REPORT page. A maximum of three failures, internal or external, present at that time, can be displayed.
NOTE: As soon as the PRESENT FAILURES SCAN function is selected, the ground contexts previously recorded are erased and thus definitively lost.
Each processor (e.g.:FMGC1 COM or FAC2 MON) can announce one failure only (the failure with the highest priority). If two failures are present at the same time, N°.1 has to be solved first so that the concerned processor can announce N°.2 in a second PRESENT FAILURES SCAN report.
The FIDS include a PROGRAM menu. When this menu is activated it allows to obtain more engineering messages (not useful at maintenance level).
5 LRU IDENTIFICATION
F LRU Identification Pages
  • This function presents, on the ground only, the PART NUMBER of the FACs and the FMGCs.
  • The page also gives the AIRCRAFT IDENTIFICATION.
NOTE: The LRU IDENT can be obtained after the power-up test only. This data is available after energization of the FAC and the FMGC as follows:
  • for the FAC, after more than 90 seconds
  • for the FMGC, after more than 120 seconds.
6 AFS TEST, LAND TEST : these two options and their operation are described in ATA REFs 22-96-00 and 22-97-00 respectively.
(3) Transmission of FLIGHT NUMBER and CITY PAIR Information
The FIDS acquires the following information from FMGC1 on line A:
. FLIGHT NUMBER Label 233, 234, 235, 236
. CITY PAIR Label 040, 041, 042
and transmits this information without check or modification to the CFDIU (parity check is performed).
** ON A/C NOT FOR ALL
4. FIDS Power Supply
  • The FIDS card is located in the FAC, on the COMMAND side.
  • The COMMAND side of the FAC and the FIDS have a common power supply.
  • The characteristics of this electrical power supply are described in ATA Ref. 22-67-00: Electrical and Hydraulic Power Supply (FAC).
** ON A/C NOT FOR ALL
5. FIDS Interface
A. ARINC Inputs/Outputs
* ARINC inputs
FAC OWN (HS)
FAC OPP (HS)
FMGC OWN A (HS)
FMGC OPP A (HS)
CFDIU (LS)
* ARINC outputs
FAC OWN COM and MON
CFDIU
NOTE: The ARINC outputs are looped back for test during the safety tests.
B. Discrete Inputs/Outputs
* Discrete inputs
SIDE 1 : ground = side 1
ATER Q : request for automatic test
LPF : Long Power Fail delivered by the COM power supply card of the FAC
TEST REQUEST : request for safety tests
NOSE GEAR OWN PRESD : ground condition
POWER FAIL : delivered by the COM power supply card of the FAC
IT POWER DOWN : delivered by the COM power supply card of the FAC
* Discrete outputs
FIDS OWN HLTY (Ref. para Safety Tests)
ATERDY : Response to automatic test request.
C. FIDS - BITE Interface
F FIDS - BITE Interface
  • The CFDIU sends a control word (label 227) in compliance with ABD018 on its FIDS bus.
  • The FIDS sends control words 354, 355, 352 and 353 to FAC1, FAC2, FMGC1 and FMGC2 respectively on its FAC1 bus.
    Words 355, 352 and 353 are transmitted via the FAC1 general bus.
  • Each FAC and FMGC transmits words 350 and 351, either spontaneously during transmission of a malfunction report, or after a FIDS command.
  • Finally, the FIDS transmits a message on word 356 to the CFDIU.
D. Interface with FMGC1
The FMGC1 transmits labels 040, 041, 042 (CITY PAIR) and 233, 234, 235 and 236 (FLIGHT NUMBER) to the FIDS. The FIDS transmits this information to the CFDIU.
** ON A/C NOT FOR ALL
6. Operation
A. General
(1) Normal Mode
The use of the system in normal mode is described in ATA REF 31-32-00.
(2) Menu Mode
  • Access to the main menu of the FIDS: chaining of the operations enabling display of this menu is described in figure:
    F Menu Chaining
  • Operating principle:
    Chaining of the various pages of the menu mode is described in figure
    F AFS - MAIN MENU Page
The following pages show an example of LAST LEG REPORT utilization.
The utilization principle is the same for the other options of the menu because the displayed data are the same.
  • Example of LAST LEG REPORT utilization
    F Example of LAST LEG REPORT Utilization (1)
    F Example of LAST LEG REPORT Utilization (2)
    These figures describe the access to the last flight failures.
  • Example of LAST LEG REPORT utilization
    F Example of LAST LEG REPORT Utilization (3)
    This figure describes the elements associated with a given failure.
    A snapshot must not be used at the maintenance level because the analysis of the snapshot requires a high engineering level.
    Message: ADIRU 1
    Failure issued by: FAC 1 COM
    RESANA: * Type/symetry: 7 ; flight and symetry
    * Error code: 17 ; IRS OWN F/W
    * EVENT: 6 ; monitoring of peripherals
    Snapshot utilization (vendor only):
    Word 1: bit 8 = 0 ; IRS OWN NOT VALID
    Word 2: bit 13 = 0 ; IRS OWN ACQ NOT HLTY
    Failure of IRS 1 acquisition by the FAC 1

B. List of LRUs Covered by the FIDS
All the internal and external LRUs covered by the FIDS are listed in the table below:
(1) List of Internal AFS LRUs
-------------------------------------------------------------------------------
!ATA REF. ! LRU ! FIN !
!----------------------!---------------------------------!--------------------!
!22-66-34 ! FAC1 ! 1CC1 !
!22-66-34 ! FAC2 ! 1CC2 !
!22-83-34 ! FMGC1 ! 1CA1 !
!22-83-34 ! FMGC2 ! 1CA2 !
!22-81-12 ! FCU ! 2CA !
!22-82-12 ! MCDU1 ! 3CA1 !
!22-82-12 ! MCDU2 ! 3CA2 !
!27-26-51 ! YAW ACTUATOR 1 ! 3CC1 !
!27-26-51 ! YAW ACTUATOR 2 ! 3CC2 !
!27-22-51 ! RUDDER TRIM ACTUATOR ! 10CC !
!27-23-51 ! RTL ACTUATOR ! 4CC !
!27-26-17 ! YAW DAMPER POS XDCR UNIT ! 2CC !
!27-92-41 ! TAKE OVER CPT ! 8CE1 !
!27-92-41 ! TAKE OVER FO ! 8CE2 !
!76-11-17 ! A/THR INSTINCTIVE DISCONNECT CPT! 7CA1 !
!76-11-17 ! A/THR INSTINCTIVE DISCONNECT FO ! 7CA2 !
!22-62-12/27-62-00 ! RUDDER TRIM RESET SWITCH ! 8CC !
!22-62-11/27-62-00 ! RUDDER TRIM CONTROL SWITCH ! 9CC !
!22-62-21 ! RUDDER TRIM INDICATOR ! 17CC !
!22-65-00 ! FAC1 PUSH BUTTON SWITCH ! 12CC1 !
!22-65-00 ! FAC2 PUSH BUTTON SWITCH ! 12CC2 !
------------------------------------------------------------------------------!

(2) List of External AFS LRUs
-----------------------------------------------------------------------------
!ATA REF. ! LRU ! FIN ! NOTE !
!----------------------!---------------------------!----------------!-------!
!31-21-21 ! CLOCK ! 2FS ! !
!34-36-31 ! ILS 1 ! 2RT1 ! !
!34-36-31 ! ILS 2 ! 2RT2 ! !
!34-51-33 ! DME 1 ! 2SD1 ! !
!34-51-33 ! DME 2 ! 2SD2 ! !
!34-55-31 ! VOR 1 ! 3RS1 ! !
!34-55-31 ! VOR 2 ! 3RS2 ! !
!34-12-34 ! ADIRU 1 ! 1FP1 ! !
!34-12-34 ! ADIRU 2 ! 1FP2 ! !
!34-12-34 ! ADIRU 3 ! 1FP3 ! !
!73-21-60/73-22-34 ! ECU 1/EEC 1 ! 4000 KS (Eng 1)! !
!73-21-60/73-22-34 ! ECU 2/EEC 2 ! 4000 KS (Eng 2)! !
!34-42-33 ! R/A 1 ! 2SA1 ! !
!34-42-33 ! R/A 2 ! 2SA2 ! !
!23-24-34 ! ACARS (FP) ! 1RB ! !
!32-31-71 ! LGCIU 1 ! 5GA1 ! !
!32-31-71 ! LGCIU 2 ! 5GA2 ! !
!28-42-34 ! FQIC ! 3QT ! !
!27-93-34 ! ELAC 1 ! 2CE1 ! !
!27-93-34 ! ELAC 2 ! 2CE2 ! !
!27-51-34 ! SFCC1 ! 21CV ! !
!27-51-34 ! SFCC2 ! 22CV ! !
!31-44-34 ! WEIGHT & BALANCE (FP) ! 1GT1, 1GT2 ! !
!31-35-22 ! PRINTER (FP) ! 4TW ! !
!34-48-34 ! GPWC ! 1WZ ! !
!31-32-34 ! CFDIU ! 1TW ! !
!31-63-34 ! DMC1 (PFD OWN VALID) ! 1WT1 ! * !
!31-63-34 ! DMC2 (PFD OPP VALID) ! 1WT2 ! * !
!31-53-34 ! FWC1 (FWC OWN VALID) ! 1WW1 ! * !
!31-53-34 ! FWC2 (FWC OPP VALID) ! 1WW2 ! * !
!32-42-34 ! BSCUA (BSCUA HLTY) ! 10GG ! * !
!32-42-34 ! BSCUB (BSCUB HLTY) ! 10GG ! * !
!24-22-55 ! 28V DC PWR SUPPLY SPLIT ! 11XU1, 11XU2 ! !
!29-32-12 ! HYD PRESS SWITCH (YELLOW) ! 3151GN ! !
!29-32-12 ! HYD PRESS SWITCH (GREEN) ! 1151GN ! !
!34-11-00 ! AIR DATA SWITCH ! 15FP ! !
!34-11-00 ! ATTITUDE SWITCH ! 13FP ! !
-----------------------------------------------------------------------------
* Discrete signal from a computer
FP : FULL PROVISION SP : SPACE PROVISION

** ON A/C NOT FOR ALL
7. Safety Tests
  • The following tests are performed automatically in the FIDS card on the ground after prolonged power supply cutoff (>4s).
    . Memory module checksum test
    . CPU RAM test
    . ARINC RAM test
    . ARINC EEPROM test
    . ARINC OUTPUT test by looping:
    * For FIDS to CFDIU, the test is performed on label 356
    * For FIDS to FAC, the test is performed on label 354.
  • In addition, the CPU card performs a SLOT test after each reset (card identifier)
  • Total duration of these tests is approximately 15 seconds.
  • Test results:
    * If all the tests are correct, the FIDS sets its FIDS HEALTHY discrete output to 1 and performs its SYSTEM BITE function (for FAC1 only)
    * If one of the tests is incorrect, the FIDS sets FIDS HEALTHY to 0 and repeats the tests.
  • For all the other energization cases, FIDS HEALTHY is set to 1.
  • Specific case of FAC2: The CPU card permanently performs the power rise tests and sets its FIDS HEALTHY discrete output to 1. If this card is faulty, a malfunction report delivered by the FAC2 declares the fault.
[Rev.10 from 2021] 2026.03.31 23:11:25 UTC
"Aviabrain" 2025