03/23/21
Message Overview:
Message Description:
L-GP-5 input to IRS 1 is inactive, while L-GP-5 input to IRS 2 is reported active.
Possible Causes:
- Internal Reference Unit (IRU) No. 1 (A233)
- Junction Box (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 |
| Removal of the Inertial Reference Unit (IRU) | AMM 34-45-01-000-801 |
| Installation of the Inertial Reference Unit (IRU) | AMM 34-45-01-400-801 |
| Standard Practices - Replace Wiring | SPM 20-12-00-02 |
| Standard Practices - Repair Wiring | SPM 20-12-10-02 |
Troubleshooting Recommendations:
- Reset IRU 1 (CB1-C2) circuit breaker.
- If system check passes, do close out.
- If fault remains, continue with next step.
- Swap IRUs.
- If system check passes, do close out.
- If fault remains, continue with next step.
- Do wiring check of the ARINC 429 data bus L-GP-5 from IRU 1 connector A233P1 to Junction Box 1. Repair/replace as required.
- If system check passes, do close out.
- If fault remains, continue with next step.
- Replace Junction Box 1.
- Do close out.