11.18 On Board Maintenance Systems Flashcards
What does CMCS stand for?
Central maintenance computer system
What does the CMCS do? [3]
- Enables ease of reporting and fault finding
- Collects reports from different systems around the aircraft during flight
- carry out functional tests on the ground
What does a CMCS consist of? (5)
- central maintenance computers (CMC) in avionic compartment
- MCDU in flight deck as main interface
- a printer
- an ACARS connection to data-link the information to home base
- a digital computer in each system which is connected to CMC
What is the range of total number of complex systems connected to the CMC?
50 to 100 systems
What are CMC’s two modes of operation?
- reporting mode
- interactive mode
What is the reporting modes function? [3]
- Active during normal flight conditions
- Scans all connected aircraft systems and logs any fault info
- this can be displayed at any time on the MCDU or printed or sent to home base by ACARS
What are interactive modes function?
- can only be selected on the ground
- used for functional checks and fault investigation
What 3 different tests can interactive mode carry out?
- system test (computer test, no moving parts)
- Complementary test (moving parts)
- output test (engineer to interact with the procedure)
What does BITE stand for?
Built in test equipment
What 2 function does BITE have?
- Detect failures
- to perform system tests on the ground
When will BITE perform system tests?
Only when on the ground, Automatically when electrical power is switched on (power up test)
What does the CMCS have if the CMC were to fail?
Has a redundancy CMC which receives the same input data, and output becomes active automatically
What does the MCDU consist of? (3)
- a control area with multiple push buttons
- annunciator lights
- display area
When is the MCDU mainly used?
During flight to control the flight management system (FMS)
How can the CMC indicate that the MCDU is faulty?
Shows a FAIL annunciator on the MCDU
What are the buttons called on the side of the display area on the MCDU?
Line select keys