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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.

For AOG assistance contact:

CRC Montreal (YUL)
Quick Links

02/28/24

Message Overview:

Message Name:

AUDIO POWER AMPLIFIER NOISE

Identifier: 442OBS001
Effectivity: Aircraft 20501 - 20999
DDG: None
System: Cabin Audio & Passenger Address
Supplemental System Description Section: 44-20-00 - In-Flight Entertainment System
Supplemental Wiring Diagram Manual: 24-03 - W1002465143 - Wardrobe DC PWR Distribution 
44-21 - W1004423123 - Cabin Audio System

Observed Fault Description:

Uncommanded sound (noise) heard through the entry speaker, cabin trim speakers and lavatory speaker. Noise can be described as whooshing, loud squeal, static. Noise is also heard in the flight crew headset when Audio Control Panel (ACP) is selected to Passenger Address (PA). 

Possible Causes:

  • AUDIO POWER AMPLIFIER (APA) (A84029)

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

NOTES:

  • The Audio Power Amplifier (APA) provides two modes, Passenger Address and Cabin Audio.
  • Bombardier has received reports of the APA causing noise on multiple speakers. If you hear a noise on multiple speakers and you cycle the breakers the amplifier may no longer function or cause the noise on the speakers and must be replaced. 
  • Consult the MMEL 23-41-01 Passenger Address (PA) System.

Quick Links:

Lufthansa Technik Technical User Guide (TUG) CL350 nice® HD C-ABT207-UG-001
Lufthansa Technik Software Load Procedure (SLP) CL350 nice® HD C-ABR142-UG-001
Operational Test Of The Passenger Address System SMM 23-31-00-710-801
Operational Test Of The Cabin Management System SMM 44-10-00-710-801
Removal of the Audio Power Amplifier SMM 44-21-09-000-801
Installation of the Audio Power Amplifier SMM 44-21-09-400-801

Troubleshooting Recommendations:

Cabin Audio Circuit Protection

Location CB Label CB Ident System
RH Secondary Power Center  INDICATING/RECORDING PAX ADDRESS CB4-F9 Passenger Address
Circuit Breaker Panel Wardrobe (CBP84003) RH AUX APA  B3-W Cabin Audio

 Troubleshooting Procedure

  1. Is an audio noise impacting multiple speakers?

    1. If YES, Continue with the next step.
    2. if NO, do close out. 

  2. Replace the Audio Power Amplifier (A84029). 
  3. Do close out. 

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