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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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03/08/21

Message Overview:

Message Name:

NO B-DCU-2 BUS OUTPUT

Message Code:

B3-006527

Associated CAS:

None

Reporting LRU: DCU 2
System Description: 31-41-00
Schematic Diagram: 31-41-00
Wiring Diagram: 31-41-01
31-41-02
31-41-03
31-41-13

Message Description:

No B-DCU-2 data received at 2-of (L-PFD, L-MFD, R-PFD, R-MFD).

Possible Causes:

  • Data Concentrator Unit (DCU) (A14)
  • Primary Flight Display 1 (PFD) (A27)
  • Primary Flight Display 2 (PFD) (A26)
  • Multi-Function Display 1 (MFD) (A29)
  • Multi-Function Display 2 (MFD) (A28)
  • Junction Box 4 (JB4)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

Quick Links:

Removal of the Junction Box JB4 AMM 24-63-13-000-802
Installation of the Junction Box JB4 AMM 24-63-13-400-802
Removal of the Data Concentrator Unit (DCU) AMM 31-41-01-000-802
Installation of the Data Concentrator Unit (DCU) AMM 31-41-01-400-802
Removal of the Adaptive Flight-Display Unit AMM 31-61-01-000-801
Installation of the Adaptive Flight-Display Unit AMM 31-61-01-400-801
Wiring - Maintenance Practices - ALL SPM 20-12-00-02
Wire Repair - Maintenance Practices - ALL SPM 20-12-10-02

Troubleshooting Recommendations:

  1. Reset the following Circuit Breakers. Is the fault message still present?

    NAME LOCATION & NUMBER
    EICAS DCU B CB2-D1
    L PFD CB1-C3
    R PFD CB2-C3
    L MFD CB1-C5
    R MFD CB2-C5

    1. If NO, do close out.
    2. If YES, continue with next step.

  2. Remove one Adaptive Flight-Display Unit at the time (3 must be connected). Is the fault message is still present?

    1. If NO, replace the defective Adaptive Flight-Display Unit.
    2. If YES, repeat this step until all 4 Adaptive Flight-Display Units are confirmed not causing the fault message, then, continue with next step.

  3. Do wiring check between DCU (A14) and the 4 Adaptive Flight-Display Units, through Junction Box 4, for the following wires:

    From To Result
    Conn. A14EP1-8A Conn. A26P2-23
    Conn. A14EP1-8B Conn. A26P2-24
    Conn. A14EP1-8A Conn. A28P2-23
    Conn. A14EP1-8B Conn. A28P2-24
    Conn. A14EP1-8A Conn. A29P2-23
    Conn. A14EP1-8B Conn. A29P2-24
    Conn. A14EP1-8A Conn. A27P2-23
    Conn. A14EP1-8B Conn. A27P2-24

    1. If the check is satisfactory, continue with next step.
    2. If the check is not satisfactory, repair defective wire or replace JB4.

  4. Replace DCU (A14).
  5. Do close out.

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