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MAINTENANCE MANUAL
CAS-100 COLLISION AVOIDANCE SYSTEM
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Table 1. TCAS System Components (Honeywell Supplied)
(cont)
Equipment Type
Honeywell
Part Number
Description
TRA-67 Transponder Subsystem (cont)
Through the directional TCAS antenna, all TCAS
equipped aircraft at intervals transmit a message
that tells other TCAS equipped aircraft that a TCAS
equipped aircraft is present. The Mode S
transponders receive the broadcast messages and
tell the TCAS processor through the ARINC 429
data link that a broadcast message was received.
The ARINC 429 data link is also used to move the
maximum airspeed, pressure altitude, aircraft
address identification, and TCAS coordination
message data from the transponder to the TCAS
processor. The TCAS processor also moves
housekeeping and coordination update data to the
transponder.
Built-in-test equipment software continuously
monitors for internal transponder failures,
transponder control unit failures, transponder
antenna failures, pressure altitude input failures,
and ARINC 429 data failures. Detailed transponder
subsystem failure status is reported to the TCAS
processor through the 429 data link. A failure of the
transponder or transponder control unit causes the
FAIL light on the transponder control unit to come
on.