M11.18 OBMS Cat A V4.1.0

Which of these units are within the Central Maintenance Computer System?

Select all correct answers

• Printer

• Central Maintenance Computer

• Multi-purpose Control and Display Unit

• Computer in each aircraft system

• ACARS control panel

Answer explanation

From; Module 11A Turbine Aeroplane Aerodynamics, Structures and Systems > 11.18 On Board Maintenance Systems (ATA 45) > Category A V4.1.0 > Page 3

The CMCS consist of:

• One or two Central Maintenance Computers (CMC) in the avionic compartment

• Two or three multi-purpose Control and Display Units (MCDU) in the cockpit as the main interface between the operator and the system • A printer in the cockpit for hard copies of the information

• An ACARS connection to data-link the information to home-base

• A digital computer in each aircraft system which is connected to the CMC in order to provide the trouble shooting information

What are the 2 modes of operation for CMCS?

Select the 2 correct answers

• Reporting

• Interactive

• Information

• Active

• Maintenance

When can interactive mode be used?

• Aircraft on the ground

• Whenever power is available to the system

• 3 minutes after engine start up

• only after all engines have been shout down

• Once engine pressure switch is lower than 3 psi.

What are the 2 functions of BITE?

Select the 2 correct answers

• Detect failures

• Perform tests on ground

• To allow maintenance testing in the air

• To automatic shut down LRUs during failure

• To isolate power from faulty circuits

When is BITE carried out automatically?

• Power on

• As soon as communication has been established with the controlling computer

• 5 seconds after power on

• They can not be done automatically. They must be initiated.

How is CMCS redundancy achieved?

• 2nd CMC is installed and becomes active automatically

• 2nd CMC is installed and becomes active when switched on via the control panel.

• FMC takes control in CMC revisionary mode automatically

• FMC takes control in CMC revisionary mode when switched on via the MCDU

How is redundancy fulfilled in Interactive mode?

• Via the Backup channel

• By selecting the other CMC via the MCDU

• By selecting the CMC via the control panel.

• Automatically via the FMC

What is MCDU used mainly for in flight?

• Controlling FMS

• Initiating BITE

• Displaying Fault data

• Displaying Navigation plots

What does the “Fail” annunciators on the MCDU indicate?

• MCDU is defective

• Navigation Inputs to the MCDU are not valid

• FMS functions are inoperative, but maintenance can still be accessed via the backup channel

• All functions except emergency communications are inoperative

How many lines and characters make up the display screen?

• 14 lines each containing 24 characters

• 24 lines each containing 10 characters

• 16 lines each containing 30 characters

• 10 lines each containing 14 characters