• TCAS FAIL Message: Notes:
  • The amber TCAS FAIL message indicates a TCAS failure. The message shows in all NAV Data Display modes regardless of whether the TFC button on the EFIS Control Panel is pressed ON or OFF.
  
  
  • The TCAS FAIL message can show for faults that are external to the TCAS Computer as well as for faults that are internal to the TCAS Computer.
  
  
  • When the selected ATC Transponder has failed the TCAS will indicate failure until the alternate operational ATC Transponder is selected.
  
  
  • An air/ground discrete short to ground, or an RA status discrete from the DEUs is grounded, can cause the TCAS FAIL message to show and will not cause a maintenance message on the TCAS Computer.
  
  
  TCAS FAIL Message Possible Causes:

  Before replacing any component perform BITE if available. (TCAS Processor and ATC Transponder bite check in main E&E.)

  
  

  1.TCAS Computer

  
  

  2.ATC Transponder

  
  

  3.Antenna

  
  

  4.Wiring

  
  
  TCAS Failed Message:

  

  
  

  

  
  Circuit Breakers:

  TCAS: P18-1 = B6.

  
  

  ATC Transponder #1: P18-1 = B5.

  ATC Transponder #2: P6-1 = D14.

  
  
  Applicable deferrals MEL 34-40 Traffic Collision / Avoidance System (TCAS)
  

Training Only