2A-31-60: Central Maintenance Computer System
1. General Description:
The central maintenance computer (CMC) system is a hardware / software
installation that provides the operation, storage and interfaces for maintenance
data. The flight crew may access data generated by the CMC by selecting the
CMC synoptic page for view on the Display Units (DUs). Data is also
downloadable by connecting a portable Personal Computer (PC) directly to the
CMC module in the MAU using ethernet ports. The CMC system performs the
following functions:
•
Stores configuration data for installed equipment including hardware /
software part numbers, serial numbers, equipment identifiers and bus
addresses in a Configuration Management System (CMS)
•
Provides fault monitoring for all interfaced components and subsystems to
generate maintenance specific messages
•
Displays parameter values and history data from monitored systems
•
Records trends and exceedance / limit data
•
Records events initiated by both crew switch activation and subsystem
diagnostic software
•
Records component operation data tracking cycles and hours of usage
•
Generates and stores maintenance messages for use in troubleshooting
and diagnostics (maintenance messages are formatted by ATA code,
component name and nature of the fault)
•
Compiles an end of flight report summarizing activity for each flight
segment
The CMC system is composed of the following subsystems:
•
Central Maintenance Computer module
•
Digital Engine Operating System (DEOS) software helper application
•
Remote terminal
•
Loadable Diagnostic Information (LDI) database
2. Description of Subsystems, Units and Components:
A. Central Maintenance Computer module:
The CMC module is installed in slot eleven (11) of Modular Avionics Unit
(MAU) #1. The module has a Pentium II processor, operates using a MS
Windows NT software system and has two front-mounted connectors to
support ethernet connections for PC readout and uploadable databases.
The module is interfaced through the MAU to the ASCB-D bus, thus
communicating with all installed aircraft components and subsystems.
Components / subsystems using ARINC 429 protocols and not directly
interfaced to the ASCB-D bus are linked through Input / Output (I/O)
modules that interface ARINC 429 data to the ASCB-D bus. All monitored
components and subsystems are considered “members” of the CMC
system.
The
member
system
concept
provides
comprehensive
maintenance and fault monitoring and has the advantage of discriminating
fault / maintenance data to isolate the faulty component or subsystem. This
effectively filters data to eliminate fault / maintenance reports where
various components / subsystems are operationally linked and failure of
OPERATING MANUAL
PRODUCTION AIRCRAFT SYSTEMS
2A-31-00
Page 21
July 15/04
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