11.18 OBMS Flashcards
What does the CMCS consist of?
- 1 or 2 CMCs
- 2 or 3 MCDU’s
- Datalink to acars
- Computer in each aircraft system
What are the 2 modes of operation for CMCS?
Reporting and Interactive
When can interactive mode be used?
AC on ground
What are the two functions of bite?
- Detect failures
- Perform tests on ground
When is bite carried out automatically?
Power on
How is CMCs redundancy achieved?
Second standby CMC
How is the standby CMC switched in?
Automatically in case of failure
- manually on some aircraft
How is redundancy fulfilled in interactive mode?
backup channel
What is MCDU used mainly for in flight?
Controlling FMS
What does the “fail” annunciators on the MCDU indicate?
MCDU is defective, use another one
How many lines and characters make up the MCDU display screen?
14 lines, each containing 24 characters
What is the top line of the MCDU called?
Title line
What is the bottom line of the MCDU called?
Scratchpad or message line
When using MCDU, when might the “no response” message be shown?
If there is a printer failure, out of paper, or in use by another system
How is the “no response” indication, indicated on airbus?
by an asterisk
How could you confirm that a recorded fault is the cause of a “cockpit effect”?
Correlation of time, date and ATA chapter
When does memorisation of faults begin?
Beginning of flight, 3 mins after engine start
When does the memorisation of faults end?
Flight is terminated during taxiing
How is an intermittent failure defined?
Occurs once or several times during flight but isn’t reported after landing
What happens to the last flight data at the beginning of the next flight?
Moved into history memory
How many previous flights is the fault history data retained for?
63
On the ground when is reporting mode terminated?
When interactive mode is selected
What are 2 main purposes of different test functions on CMC?
- Confirm most likely reported LRU is faulty
- Confirm component repair or removal solved problem
What three tests can be carried out?
- System
- complementary and output
Why arent tests allowed during flight?
In case flight safety is influenced
How can tests be enabled manually?
ground test enable switch
What happens to the system with the ground test enable switch in the normal position?
all test signals are interrupted
What special precautions are needed for a system test?
None, it is only a computer test of the system
Which test requires preconditions?
complementary test
What is displayed when you carry out a complementary test?
- Caution message
- moving surfaces
Why is the final selection of the complementary test a different line select key than the previous page?
To ensure the operator is fully aware of what is going to happen
What is necessary at the end of the complementary test?
A close up, to bring AC back to original condition
What is the main purpose of the output test?
To trigger a cockpit function for the operator to monitor
How is a successful output test indicated?
It isn’t, it is determined by the operator dependent on the indicator response
How often must the FMS nav database update be updated?
28 days
How can data loading be carried out?
- Airborne data loader
- Portable data loader
- Cross loading between computers
When does the FMC data loading page appear automatically?
When 2 FMC’s detect different part numbers at power on
