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MAINTENANCE MANUAL
CAS-100 COLLISION AVOIDANCE SYSTEM
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Table 17. ITA-81A Traffic Display Inputs and Outputs
C. TCAS Failure Monitoring
The TCAS system includes extensive Built-In-Test Equipment (BITE) monitoring. BITE does
full-time monitoring of the TCAS system components. Primary failures are shown on the
screen of the PPI or dedicated traffic display, and on different FAIL lamps and flags throughout
the system. BITE monitoring is totally transparent to the pilot and does not effect the TCAS
operation unless a failure is found. When a primary system failure is found, specified LRU
(line replaceable unit) failures are shown on the PPI or dedicated traffic display. If a PPI
weather/traffic display is used in a weather mode, TCAS FAIL will be annunciated. When the
display is set to TCAS mode, the specified LRU failure(s) is shown.
BITE monitors the internal operation of the system components and I/O data links.
When a TCAS FAIL condition is found, TCAS stops all surveillance and tracking functions.
NOTE:
A complete description of BITE monitoring operations and their failure
annunciations
and indicators, is contained in the TESTING AND FAULT ISOLATION and in the
MAINTENANCE PRACTICES sections of this manual.
Source Or
Destination
I/O Signal
Name and Type
General
Description
TCAS PROCESSOR RELATED I/O
TCAS Processor
TCAS Data High-Speed ARINC
429
Traffic display data from TCAS
processor to dedicated TCAS traffic
display.
Display Status No. 3 Discrete
Supplies dedicated display failure
status to TCAS processor.
Traffic Alert Display Enable
Discrete
TCAS processor discrete output sets
the power supply of dedicated display.
POWER RELATED I/O
Own Aircraft Power
Supplies
115 V 400 Hz
Supplies the primary power to
dedicated TCAS traffic display.
Own Aircraft Dimmer
Bus
5 V ac
Controls panel background lighting on
dedicated display.