03/10/21
Message Overview:
Message Description:
Remote Data Concentrator (RDC) channel A buses are reported inoperative by Data Concentrator Unit (DCU) channel A and B.
Possible Causes:
- Remote Data Concentrator (RDC) (A13)
- EICAS RDC A Circuit Breaker (CB1-D2)
- Left Circuit Breaker Control Panel (CBP1)
- Junction Box 1 (JB1)
- Associated Wiring
Troubleshooting Tips:
Advisory Wire/Service Bulletin: None
Forum Articles/Infoservice/Newsletter: None
Quick Links:
| Removal of the Junction Box JB1 | AMM 24-63-01-000-802 |
| Installation of the Junction Box JB1 | AMM 24-63-01-400-802 |
| Replacement of DC Circuit Breakers | AMM 24-65-00-960-801 |
| Removal of the Cockpit Circuit-Breaker Panel (CCBP) | AMM 24-65-01-000-801 |
| Installationof the Cockpit Circuit-Breaker Panel (CCBP) | AMM 24-65-01-400-801 |
| Removal of the Remote Data Concentrator (RDC) | AMM 31-41-05-000-802 |
| Installationof the Remote Data Concentrator (RDC) | AMM 31-41-05-400-802 |
| Wiring - Maintenance Practices - ALL | SPM 20-12-00-02 |
| Wire Repair - Maintenance Practices - ALL | SPM 20-12-10-02 |
Troubleshooting Recommendations:
- Reset EICAS RDC A Circuit Breaker CB1-D2. Is the fault message still present?
- If NO, do close out.
- If YES, continue with next step.
- Confirm RDC strapping at RDC (A13).
Measurements at Expected Result Result Conn. A13CP1-7B Aircraft Ground Conn. A13CP1-8K Aircraft Ground Conn. A13CP1-7A Aircraft Ground Conn. A13CP1-7K Aircraft Ground - If the check is satisfactory, go next step.
- If the check is not satisfactory, repair defective wire.
- Confirm presence of the grounds at RDC (A13).
Measurements at Expected Result Result Conn. A13CP1-2A Aircraft Ground (PWR GND) Conn. A13CP1-2B Aircraft Ground (PWR GND) Conn. A13CP1-7C Chassis Ground Conn. A13CP1-7D Chassis Ground Conn. A13CP1-7G Chassis Ground Conn. A13CP1-7H Chassis Ground - If the check is satisfactory, go to next step.
- if the check is not satisfactory, repair defective wire.
- Confirm presence of the 28 VDC at RDC (A13).
Measurement at Expected Result Result Conn. A13CP1-1A 28 VDC Conn. A13CP1-1B 28 VDC - If the check is satisfactory, replace defective RDC (A13).
- If the check is not satisfactory, go to next step.
- Do wiring check between RDC (A13) and the left Circuit Breaker Panel (CBP1) for the following wires:
From To Result Conn. A13CP1-1A Conn. CBP1J1-41 Conn. A13CP1-1B Conn. CBP1J1-41 - If the check is satisfactory, continue with next step.
- If the check is not satisfactory, repair defective wiring or defective Junction Box 1.
- Replace EICAS RDC A Circuit Breaker CB1-D2. Is the fault message is still present?
- If NO, do close out.
- If YES, continue with next step.
- Replace left Circuit Breaker Panel (CBP1).
- Do close out.