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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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Quick Links

04/10/25

Message Overview:

Message Name:

NO AUDIO IN COCKPIT SPEAKERS OR HEADPHONES

Identifier: 235OBS002
Effectivity: AIRCRAFT: 20501 - 21399
System: Communication
System Description: 23-51-00 - Audio Integrating System
Schematic Diagram: 23-51-00 - Audio Integrating System
Wiring Diagram: 23-51-03 - Pilot / Co-Pilot Emergency Audio Integration System
23-51-05 - Audio Control Panel No.1
23-51-09 - Control Panel Electronic (CPE)
23-51-11 - Audio Integrating Data-Bus

Message Description:

There is no audio coming out of the cockpit speakers or the headphones.

Possible Causes:

  • Cockpit Headphones
  • Left Cockpit Speaker (LS1)
  • Right Cockpit Speaker (LS2)
  • Oxygen Mask
  • L Control Panel Electronics (CPE 1) (A167)
  • R Control Panel Electronics (CPE 2) (A168)
  • L Radio Interface Unit (RIU 1) (A17)
  • R Radio Interface Unit (RIU 1) (A18)
  • L Audio Control Panel (ACP 1) (PL1)
  • R Audio Control Panel (ACP 2) (PL2)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin:

  • AW300-23-0365 - ACP and CPE 4100 series Aural Warning too loud and support discontinuance
  • AW300-23-0312 - Use of Commercially Available Aviation Headsets

Full Throttle Blog/Forum Articles/Infoservice/Newsletter: None

Flight Operation Notifications Manual (FONM): None

Quick Links:

Standard Aircraft Configuration for Maintenance AMM 12-00-00-867-803
Removal of the Audio Control Panel AMM 23-51-05-000-801
Installation of the Audio Control Panel AMM 23-51-05-400-801
Removal of the Control Panel Electronic (CPE) AMM 23-51-09-000-801
Installation of the Control Panel Electronic (CPE) AMM 23-51-09-400-801
Removal of the Radio Interface Unit (RIU) AMM 23-51-21-000-801
Installation of the Radio Interface Unit (RIU) AMM 23-51-21-400-801
Open the Left Circuit-Breaker-Panel (LCBP) AMM 24-65-01-010-801
Close the Left Circuit-Breaker-Panel (LCBP) AMM 24-65-01-410-801
Open the Right Circuit-Breaker-Panel (RCBP) AMM 24-65-01-010-802
Close the Right Circuit-Breaker-Panel (RCBP) AMM 24-65-01-410-802

Troubleshooting Recommendations:

  1. Make sure the following circuit breakers (CB) are all set to IN:

    Circuit Breaker Name
    L AUDIO PWR 1
    L AUDIO PWR 2
    R AUDIO PWR 1
    R AUDIO PWR 2
    RIU 1A
    RIU 1B/AURAL
    RIU 2A
    RIU 2B/AURAL

    1. If a CB is OUT, investigate the reason and set to IN if possible and do close out.
    2. If all CBs are set to IN, continue with next step.

  2. Make sure both Audio Control Panels are set correctly. You may use the Operational Test of the Audio Control Panel (AMM 23-51-05-710-801) to check the panel configuration.

    1. If issue is still present, continue with next step.
    2. If issue is no longer present, do close out.

  3. Are all headphones, Speakers or oxygen mask audio affected?

    1. If YES, continue with next step.
    2. If only one audio output (HDPH, O2 mask or SPKR), perform a wiring check between the affected output and the associated CPE. Repair defective wiring as required.
      NOTE: If only the headphones are affected, make sure to verify the headphones themselves for any HI/LO or volume switch that may be in the wrong setting.

  4. Are both Audio systems (1 and 2) affected by this condition?

    1. If both sides are affected by this condition, go to step 6.
    2. If only the left side or right side is affected, continue with next step.

  5. Swap ACP 1 with ACP 2. Did the fault transpose to the other side?

    1. If YES, replace defective ACP.
    2. If NO, continue with next step.

  6. Swap CPE 1 with CPE 2. Did the fault transpose to the other side?

    1. If YES, replace defective CPE.
    2. If NO, continue with next step.

  7. Swap RIU 1 with RIU 2. Replace defective unit if required.
  8. Do close out.

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