03/10/21
Message Overview:
Message Description:
Data Concentrator Unit (DCU) channel A indicates it is missing computed air speed from the Right Air Data Computer (ADC), while R-ADC bus is present at the Right Input/Output Concentrator (IOC) and the R-GP-5 bus is not reported inoperative by DCU channel A.
Possible Causes:
- Right Air Data Computer 2 (ADC) (A2)
- Right Input/Output Concentrator 2 (IOC) (A4-IOC2)
- Data Concentrator Unit (DCU) (A14)
Troubleshooting Tips:
Advisory Wire/Service Bulletin: None
Forum Articles/Infoservice/Newsletter: None
Quick Links:
| 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 Input/Output Concentrator Unit (IOC) | AMM 31-45-05-000-801 |
| Installation of the Input/Output Concentrator Unit (IOC) | AMM 31-45-05-400-801 |
| Removal of the Air Data Computer | AMM 34-13-01-000-801 |
| Installation of the Air Data Computer | AMM 34-13-01-400-801 |
| Wiring - Maintenance Practices - ALL | SPM 20-12-00-02 |
| Wire Repair - Maintenance Practices - ALL | SPM 20-12-10-02 |
| Electrical Connectors - Maintenance Practice - ALL | SPM 20-20-00-02 |
Troubleshooting Recommendations:
- Reset EICAS DCU A Circuit Breaker CB1-D1, L IAPS Circuit Breaker CB1-B6 and AIR DATA 2 Circuit Breaker CB2-C1. Is the fault message still present?
- If NO, do close out.
- If YES, continue with next step.
- Check in the Maintenance Diagnostic Computer (MDC) in ATA 34 for fault related to the Right ADC.
- If other fault is posted, do the respective troubleshooting.
- If no other fault is posted, continue with next step.
- Swap L IOC with R IOC. Is the fault message still present?
- If YES, continue with next step.
- If NO, replace defective IOC.
- Replace DCU (A14).
- Do close out.