User Manual

maintenance 523-0 809018
Table 4-3. LED Descriptions - Continued
Indicator Color Description
ALTITUDE FAULT indicator will light whenever the selected altitude source is
failed or missing.
ALTITUDE
INPUT
RED
If this is lit, check the transponder control panel to see if it is indicating that it is
sending a valid altitude. If the transponder control panel is not sending the altitude,
check to v erify that the ADC on the PFD which is coupled to the autopilot is sending
valid information.
The RAD ALT INPUT indicator will light whenever the selected radio altitude inputs
are missing, or when there are two radio altitude inputs and they are n ot in agreement.
RAD ALT INPUT R ED
If this is lit and there are two radio altimeters, try turning o ff one at a time to see if
the failure goes away. If the failure persists or if there is only one radio altimeter,
check th e wiring from the radio altimeter.
The HEADING INPUT indicator will light whenever one of t he following is missing:
selected heading, pitch angle, roll angle, or true heading.
HEADING INPUT RED
These are optional parameters for the TCAS function. If these parameters are not
available, the Traffic Surveillance System will work properly.
The R/A DISP LAY indicator will light whenever either R/A display discrete input is
not grounded.
R/A DISPLAY RED
If this i s lit, check that both the left and right displays are active and can display TCAS
traffic. Push the TCAS test button, if the targets do not appear on one of the displays –
check the TA/RA port to that display. If the targets are shown on all displays, check
the RA discrete connection from the display to the TSS.
The T/A DISPLAY indicator will light whenever either T/A display discrete input is
not grounded.
T/A DISPLAY RED
This is a legacy TCAS discrete input an d is not generally used any m ore. If this is
lit check to make sure that the straps setting the two T/A discrete inputs are correctly
strapped to ground.
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