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(WARNING)
RED MESSAGE (CAUTION)
AMBER MESSAGE (ADVISORY)
CYAN MESSAGE (STATUS)
WHITE MESSAGE Require immediate crew attention. These messages are accompanied by flashing master warning, triple chime attenson with or without voice message or dedicated tone. Require immediate crew awareness and future crew action may be required in the form of alternate system selection or performance limitation. These message are accompanied by flashing master caution and a single chime. Indicate safe or normal system operation which require crew awareness, over and above the dark cockpit philosophy. Indicate minor failures or reduction in systems capability, which require no crew action.

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06/22/21

Message Overview:

Message Name:

VHF NOCOMM ON FMS CDU

Message Code: 232OBS006
Effectivity: All
System: Communication
Associated CAS: None
System Description: 23-23-00
Schematic Diagram: 23-23-00 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Wiring Diagram: 23-23-01 [ Global Express ]  [ G5000 ]  [ Global XRS ]

Message Description:

Airborne Data Link Unit (ADLU) sets VHF NOCOMM message when no Very High Frequency (VHF) communication detected.

Possible Causes:

  • Very High Frequency (VHF) Modem
  • Very High Frequency (VHF) Communication Unit 3 (A226)
  • Very High Frequency (VHF) Communication Antenna 3 (E56)
  • Very High Frequency (VHF) Communication In-line Filter (FL8)
  • Airborne Data Link Unit (ADLU) (A239)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

No connection can be made with the vhf modem. Failure Built-In Test (BIT) is set when vhf modem access fails and cleared when vhf modem access succeeds. User must initiate action to set/clear this Built-In Test (BIT). Make sure aircraft is within VHF range of ACARS data communication ground station and VHF COM 3 is operative.

Quick Links:

Operational Test of the VHF Communication System AMM 23-11-00-710-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Configuration Setting of the VHF Communication Units AMM 23-11-01-280-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Removal of the VHF Communication Unit AMM 23-11-01-000-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Installation of the VHF Communication Unit AMM 23-11-01-400-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Operational Test of the VHF Communication Units AMM 23-11-01-710-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Removal of the VHF Antennas AMM 23-11-05-000-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Installation of the VHF Antennas AMM 23-11-05-400-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Operational Test of the Data Link System AMM 23-23-00-710-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Removal of the Airborne Data-Link Unit AMM 23-23-01-000-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Installation of the Airborne Data-Link Unit AMM 23-23-01-400-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Wire Repair - Maintenance Practices - ALL SPM 20-12-10-02 [ Global Express ]  [ G5000 ]  [ Global XRS ]

Troubleshooting Recommendations:

  1. Ensure that the VHF coverage and VHF ACARS services are available (May need to coordinate with the VHF ACARS ground service provider).
  2. Check the VHF COM 3 system components and/or functions are satisfactory.

    1. If the VHF COM 3 system components and/or functions are satisfactory, do close out.
    2. If VHF COM 3 system cannot receive and/or transmit data or one of its other functions is not available, continue with next step.

  3. Check if VHF COM 3 is energized.

    1. If the unit does not receive power, troubleshoot power source from SPDA 4 and continue with next step.
    2. If the unit receives power, continue with next step.

  4. After the Power On Self Test (POST), does the Radio Management Unit (RMU) display the RADIO TUNING Page?

    1. If YES, go to step 11.
    2. If NO, continue with next step.

  5. Go to the SYSTEM TEST RESULTS and the RADIO TEST RESULTS pages.
  6. Check if the fault message CHK RMU 1 (2) is present.

    1. If the fault message CHK RMU 1 (2) is present, troubleshoot it first and continue with next step.
    2. If the fault message CHK RMU 1 (2) is not present, continue with next step.

  7. Check if the fault message CHK COM 3 UNIT is present.

    1. If the fault message CHK COM 3 UNIT is present, troubleshoot it first and continue with next step.
    2. If the fault message CHK COM 3 UNIT is not present, continue with next step.

  8. Check if the fault message RMU 1 (2) ERR is present.

    1. If the fault message RMU 1 (2) ERR is present, troubleshoot it first and continue with next step.
    2. If the fault message RMU 1 (2) ERR is not present, continue with next step.

  9. Check if the fault message COM 3 UNIT is present.

    1. If the fault message COM 3 UNIT is present, troubleshoot it first and continue with next step.
    2. If the fault message COM 3 UNIT is not present, continue with next step.

  10. Check if the fault message COM 3 ERR is present.

    1. If the fault message COM 3 ERR is present, troubleshoot it first and continue with next step.
    2. If the fault message COM 3 ERR is not present, continue with next step.

  11. Perform the operational test of the VHF COM 3 unit (AMM 23-11-01-710-801).

    1. If the RMU displays a red ERR legend, perform the appropriate troubleshooting and continue with next step.
    2. If the RMU displays a PASS legend, continue with next step.

  12. Perform a wiring check between VHF COM unit 3 connector (A226P1) and SPDA 4 connector (A16P1).

    1. If wiring checks are not good, repair defective wiring as required and do close out.
    2. If wiring checks are good, continue with next step.

  13. Perform a wiring check of the VHF COM 3 antenna cable between the unit mounting tray (A226P3) and the antenna connector (E56).

    1. If wiring checks are not good, repair defective wiring as required and do close out.
    2. If wiring checks are good, continue with next step.

  14. Re-install the VHF COM 3 unit and perform a resistance check at the antenna connector (E56). The resistance between the center conductor and the outer conductor should be approximately 50 Ohms.

    1. If the resistance is no as specified above, repair defective wiring or replace VHF COM 3 unit as required and do close out.
    2. If the resistance is as specified above, continue with next step.

  15. Operate the Airborne Data-Link System using VHF network to receive the terminal text weather information. Is the terminal text weather information displayed?
    NOTE: Do the initialization of the Flight Management System (FMS). Deactivate SATCOM and Telephony systems by respective circuit breakers.

    1. If YES, verify that CAIMS fault code 2320008TDY "ADLU VHF MODEM FAULT" is not displayed on PMAT and do close out.
    2. If NO, continue with next step.

  16. Perform a continuity check between short to ground and pin/socket retention check between the ADLU connector (A239BP1) and the VHF COM 3 connector (A226P1). Is the wiring continuity between short to ground and pin/socket retention check between ADLU and the VHF COM 3 satisfactory?

    1. If NO, repair or replace the defective wiring as required per WM 20-12 and do close out.
    2. If YES, continue with next step.

  17. Replace the Airborne Data-Link Unit (ADLU) (ADLU VHF MODEM FAULT is faulty).
  18. Do close out.

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