Using Transponder/Tcas Control Unit; Dual Mode S Equipped Aircraft; No Malfunctions Reported - Honeywell CAS-100 Maintenance Manual

There are two different procedures to start and monitor functional self test of the TCAS/Mode
S system. The first is started at the transponder/TCAS control unit and the sensed failures are
shown on the traffic display, but for the IVA-81A/D TA/VSI. The second procedure is started
in the equipment bay using the two buttons found on the front panel of the TCAS processor,
and then monitoring the TCAS Processor front panel LED display.
Prior to performing TCAS/Mode S system self test, make sure that these aircraft systems are
energized and operate without the failure flags on the applicable cockpit instruments:
• Air Data Systems
• Radio Altimeter Systems
• Altitude (Vertical Gyro) Systems
• Heading (Compass) Systems
If the attitude and point data supplied to the TCAS system is from an AHRS, IRS, or INS, they
must be aligned and in operate mode.
B. Using Transponder/TCAS Control Unit
NOTE: If a PPI Radar/TCAS display is used as the traffic display and has a TCAS mode on
the selector switch, it must be turned to the TCAS position for the test. If not, the
selector switch must turn to the OFF position to let the traffic display set discrete (from
the TCAS processor) and turn the display ON. It takes approximately 5 seconds for
the display to get warm after the test is started.
(1)

Dual Mode S Equipped Aircraft

The aircraft with two Mode S units, set the transponder selector on the CTA-81A Control
Unit to Position 1 to test transponder 1. Turn the function selector counterclockwise to
the TEST position (ATC 1 TEST position on CTA-81B) and hold the switch in this position
for the minimum one second. The self-test continues automatically for approximately 12
seconds. On the CTA-81 ( ) Control Unit, the display window shows ATC12R and the
ATC FAIL lamp comes on for approximately 3 seconds.
(2)

No Malfunctions Reported

If there are no malfunctions, the test sequence will be as follows:
(a) A test pattern comes into view on the displays to check each type of intruder
symbol. See Figure 1001.
(b) For the aircraft that have RA/VSI:
1 During the first seconds of the test, the RA/VSI red and green circumference
lamps (climb/descend indicators) come on together. The TCAS flag is in the
view during the test period.
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MAINTENANCE MANUAL
CAS-100 COLLISION AVOIDANCE SYSTEM
34-45-47
Page 1002
1 Dec 2003