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1 Dec 2003
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MAINTENANCE MANUAL
CAS-100 COLLISION AVOIDANCE SYSTEM
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7. Controls and Indicators
A. General
The primary manual controls used to operate the CAS-100 system are contained on the
transponder/TCAS control units.
NOTE:
TCAS advisory and/or serviceable status indications are given on the TA/VSI, RA/VSI,
PPI, dedicated traffic display, cockpit audio system, transponder/TCAS control unit,
front panel of the TCAS processor, and front panel of the Mode S transponder unit.
It is possible to supply the control of traffic advisory display range selection at a distance from
the transponder/TCAS control unit or locally through a front panel range selector switch or
switches. The control is supplied depending upon type of display unit used and display unit
configuration strapping.
B. TCAS Input Power Control
115 V 400 Hz or 28 V dc primary power, 26 V ac reference power, and 5 V ac or dc or 28 V dc
background panel lighting power are applied to TCAS by closing aircraft circuit breakers.
TCAS does not contain a power on/off switch or fuses.
C. CTA-81( ) Control Unit
See Figures 10 and 11. The CTA-81( ) Control Unit is the primary control for both TCAS and
the transponder. The CTA-81A Control Unit is used in the installations containing two
TRA-67A Mode S transponders. The CTA-81B is used in the installations containing one
TRA-67A Mode S transponder and one ATCRBS transponder. The Tables 18 and 19 give the
functions of the controls and indicators on the control units.
D. CTA-100A Control Unit
See Figure 12. The CTA-100A is an upgraded and enhanced microprocessor-based
transponder control panel for controlling maximum two TRA-67A ATC transponders and the
TPA-81A/TPA-100A TCAS processors. The CTA-100A controller is supplied with two basic
front panel configurations, a rotary control version and a keypad entry version. The CTA-100A
can facilitate the front panel interchangeability. It is made in all functional configurations of the
CTA-81( ) control panels with the same connector configuration and is applicable for a
one-for-one component change-out. The Table 20 gives the functions of the controls and
indicators on the control unit.