Fleet Type: 700
Applicable Reference:
SDS AMM part 1, 34-53-00-008, AMM 34-53-00/501, SSM 34-53-21
Discrepancy:
TCAS Fail comes on when #1 ATC selected, Ok with #2 ATC selected. Both systems BITE tests good
Possible Fix:
Correct program pins at failed ATC transponder.
Tip:
Using ground test equipment, compare information transmitted by each ATC and look for large differences of
information.
In this case the common pin at the Dip switchs for the #1 ATC transponder was open. This resulted in a aircraft ID of
all O’s when the #1 ATC was selected.
Reason/Explanation:
The ATC’s do not fail themselves when they do not have a valid aircraft ID progamed. But in order for the TCAS to
operate correctly it must have a valid aircraft Mode S ID to coordinate with other TCAS capable aircraft. This resulted in a TCAS fail when TCAS was placed in a operational mode. But the passed self test when the TCAS and the ATC were tested individually.
Thanks to Tom S. for his input.
