FAULT ISOLATION FUNCTION - PRINCIPLE - DESCRIPTION AND OPERATION________________________________________________________________
1. General_______
A. Line Maintenance
R 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).
R R R (2) The BITE and TEST software is only allowed to read the variables of the operational software.
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(Ref. Fig. 001)
-------------------------------------------------------------------------------FIN | FUNCTIONAL DESIGNATION | PANEL|ZONE|ACCESS | ATA | | | | DOOR | REF.
-------------------------------------------------------------------------------1CA1 FMGC-1 83VU 122 824 22-83-34 1CA2 FMGC-2 84VU 128 824 22-83-34 2CA FCU 13VU 211 831 22-81-12 3CA1 MCDU-1 11VU 211 831 22-82-12 3CA2 MCDU-2 11VU 211 831 22-82-12 1CC1 FAC-1 83VU 127 824 22-66-34 1CC2 FAC-2 84VU 128 824 22-66-34
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)
R . Flight Control Unit (Channels 1 and 2) . MCDUs 1 and 2.
B. Description
(Ref. Fig. 002)
(1) FIDS card:
The FIDS card includes:
-
a CPU (Microprocesseur 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.
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R Component Location Figure 001
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INTENTIONALLY BLANK
1 1
22-91-00Page 4
1 1 Feb 01/98 1 1 1CES 1
R Functional Block Diagram Figure 002
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(2) AFS BITE
- The BITE is an electronic device (HARDWARE + SOFTWARE) located
inside each AFS computer.
R - Its main function is to detect, isolate and store the system
R failures in the non-volatile memories.
R
R - There are different AFS BITE architectures:
R * COM/MON with two level of analysis: FAC and FG
R * single computer with one level of analysis: FM
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