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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:

COMM AUDIO BLEEDING ON HEADPHONE OUTPUTS

Message Code: 231OBS002
Effectivity: All
System: Audio Integrating System
System Description: 23-51-00
Schematic Diagram: 23-51-00 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Wiring Diagram: 23-51-51 [ Global Express ]  [ G5000 ]  [ Global XRS ]

Message Description:

Noise can be heard on the Cockpit Headsets when all Audio Selectors are selected to the OFF position. The Com bleeding is associated with the installation of the Audio Control Panel (ACP) (and is not dependent on ACP part number). Bombardier was able to reproduce the snag on multiple aircraft. The low level noise that can be heard is voice from either active COM frequency with various combinations of the intercom and headphone volume settings.

Possible Causes:

  • Audio Control Panel (ACP) 1 (A8)
  • Audio Control Panel (ACP) 2 (A9)
  • Audio Control Panel (ACP) 3 (A215)

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

See MODSUM IS700-23-0002 ACP Wiring Change to Prevent COMM Audio Bleeding on Headphone Outputs-Audio Integrating System.

Quick Links:

Removal of the Audio Panels AMM 23-51-05-000-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Installation of the Audio Panels AMM 23-51-05-400-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]

Troubleshooting Recommendations:

Fault confirmation:

  1. This condition can be monitored on the aircraft and from any position (ACP 1, ACP 2 or ACP 3), when the ACP is setup as follows:

    • All audio volume knobs selected off (pushed in)
    • All TRANSMIT push button to off (pushed out)
    • The Audio Panel is in Hot Mic (H’MIC button pushed out)
    • RMU’s are tuned to active frequency (like ATIS)

  2. With the above ACP configuration, a low level voice from either active COM frequency (ATIS in that case) can be herd as a background on cockpit headset with different combination of intercom (INT) and HEADPHONE volume settings.
  3. Further testing showed that the bleeding COM voice can be heard more clearly when:

    • HEADPHONE volume knob is set to 2 o’clock position and INT at 4 o’clock position OR
    • HEADPHONE volume knob is set to 4 o’clock position and INT at 2 o’clock position

Solution:

Based on Honeywell recommendation, Bombardier released MODSUM IS700-23-0002 that provides all necessary instructions to perform installation wiring change for all audio panels as installed on the Global platform. This modification was introduced on production from aircraft SN 9270.

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