30 Questions
What is the primary function of the Central Maintenance Computer?
To acquire and process data from BITE memories
What is the purpose of the Multipurpose Control and Display Units?
To control interrelated systems and display relevant output messages
In which mode can the operator obtain troubleshooting data from the systems?
Menu mode
What is the characteristic of the Normal Mode of the Central Maintenance System?
Based on permanent real-time memorisation of fault data
What is the output of the Flight Warning Computers in the Central Maintenance System?
Fault messages
Where is the fault data memorised in the Central Maintenance System?
In both the system computers and the CMCs
What is the primary function of the On-board Maintenance System (OMS) in aircraft?
To assist maintenance personnel in fault-finding of complex avionics systems
Which system is responsible for initializing tests on aircraft systems in modern aircraft?
Central Maintenance System (CMS)
What is the main benefit of using the On-board Maintenance System (OMS) in aircraft maintenance?
Minimizing ground time and increasing maintenance efficiency
What are the main components of the Central Maintenance System (CMS)?
Central Maintenance Computers (CMC) and Multipurpose Control and Display Units (MCDU)
Which of the following is NOT a function of the On-board Maintenance System (OMS)?
Flight navigation
What is the result of using the On-board Maintenance System (OMS) in aircraft maintenance?
Improved cost effectiveness
What information does the CMC memorise at each leg opening transition?
Leg heading, date, flight number, city pair from, start time, and A/C identification
What is the primary purpose of having two CMCs in large modern commercial aircraft?
For redundancy purposes
What happens when the off legend illuminates on the pushbutton switch in the cockpit overhead panel?
CMC 2 becomes active and considered the master
What is the result of a CMC BITE failure?
A failure indication is displayed on the MCDU and printer
How can the CMC be switched in normal operation?
Through a BITE fault, MCDU selection, or a pushbutton switch
What is the purpose of the Management Unit (MU) in the ACARS system?
To send failure details to the main base
What is the primary function of the Aircraft Communication Addressing and Reporting System (ACARS)?
To send maintenance information from the aircraft to maintenance personnel at the destination station
What is the main purpose of a data loader in an aircraft?
To update software on the aircraft's onboard computers
What is the benefit of integrating the Central Maintenance Computer (CMC) with the Aircraft Communication Addressing and Reporting System (ACARS)?
It enables maintenance personnel to begin troubleshooting before the aircraft's arrival
What is the role of the Central Maintenance Computer (CMC) in relation to the Aircraft Communication Addressing and Reporting System (ACARS)?
It interfaces with ACARS to send maintenance information to destination stations
What is the purpose of a data bus coupler in relation to the data loader?
It links the data loader to the Flight Management System (FMS)
What type of communication systems can the Central Maintenance Computer (CMC) integrate with?
Wireless LAN, Satellite Communication (SATCOM), and Aircraft Communication Addressing and Reporting System (ACARS) systems
What type of media is commonly used in newer airborne data loaders for the transfer of information into the aircraft?
PCMCIA cards or Universal Serial Bus (USB) sticks
What is the purpose of loading Loadable Software Aircraft Part (LSAP) into the target hardware?
To update software
What is required after loading a Loadable Software Aircraft Part (LSAP) into the target hardware?
A Certificate of Release to Service
What is the purpose of the Aircraft Configuration List (ACL)?
To record software updates
What type of card is used in some airborne data loaders?
PCMCIA card
What is used to load software into the target hardware?
Portable Data Loader (PDL)
Study Notes
Central Maintenance System (CMS)
- Acquires and processes data from BITE memories of system computers
- Operates in two modes: normal mode and menu mode
- Normal mode:
- Records fault messages generated by Flight Warning Computers (FWC) and failure information produced by BITE function
- Based on permanent real-time memorisation of fault data or operational BITE
- Menu mode:
- Allows operator to obtain troubleshooting data from systems and initiate self-tests via MCDU
- Only available on the ground
Central Maintenance Computer (CMC)
- Provides a centralised location for aircraft fault information
- Files current flight and updates the 64 last legs filed in the previous flight report
- Memorises new leg heading: date, flight number, city pair from, start time, and A/C identification
- At each leg closing transition, CMC memorises end time and city pair to
On-Board Maintenance System (OMS)
- Developed to assist maintenance personnel in fault-finding of complex avionics systems
- Uses a range of techniques built into and integrated with aircraft systems
- Minimises ground time, increases efficiency of maintenance processes, and improves cost-effectiveness
- Consists of: Central Maintenance System (CMS), Data Loading System, Electronic Library System, and Report Printing System
CMC Switching Control and Self-Test Function
- Typically, two CMCs are available in large modern commercial aircraft for redundancy purposes
- CMC 1 is the master in normal operation
- CMC can be switched through a BITE fault, MCDU selection, or a pushbutton switch in a cockpit overhead panel
- If CMC 2 is active, the off legend illuminates on the pushbutton
Aircraft Communications Addressing and Reporting System (ACARS)
- CMC can integrate with ACARS, Satellite Communication (SATCOM), wireless LAN, and other communication systems
- Allows maintenance personnel at the destination to begin troubleshooting process and analysis before the aircraft arrives
Data Loading System
- Used to load and update software on aircraft systems
- Typically, data loaders are linked with the Flight Management System (FMS) or connected to a data bus coupler
- Data loaders can be portable or integrated into the avionics system
- Can be used to install and update software or download data recorded by on-board computers during aircraft operation
Learn about the On-Board Maintenance System (OMS) used in aircraft to assist maintenance personnel in fault-finding and troubleshooting of complex avionics systems. Understand its functions and applications in aircraft maintenance and engineering.
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