02/02/26
Message Overview:
Message Name:
SPC CHANNEL B INPUT
Message Code:
B3-006856
Associated CAS:
| Reporting LRU: | HORIZ TRIM ECU |
| System Description: | 27-32-00 - Stall Protection System (SPS) 27-41-00 - Pitch Trim System |
| Schematic Diagram: | 27-41-00 - Pitch Trim System |
| Wiring Diagram: | 27-41-21 - Horizontal Stabilizer -Trim Electronic Control Unit (HST ECU |
Message Description:
Stall Protection Computer (SPC) Channel B input fail detected by the Horizontal Stabilizer Electronic Control Unit (HST ECU).
Possible Causes:
- Stall Protection Computer (SPC) (A178)
- Horizontal Stab Trim Electronic Control Unit (HST ECU) (A130)
- Right Input/Output Concentrator (R IOC) (A4-IOC)
- Associated Wiring
Troubleshooting Tips:
Advisory Wire/Service Bulletin: None
Full Throttle Blog/Forum Articles/Infoservice/Newsletter: None
Flight Operation Notifications Manual (FONM): None
Quick Links:
| General Setup for Maintenance | |
|---|---|
| Standard Aircraft Configuration for Maintenance | AMM 12-00-00-867-803 |
| Electrical/Electronic Safety Precautions | AMM 24-00-00-910-801 |
| Electrostatic Discharge Safety Precautions | AMM 24-00-00-910-802 |
| Maintenance Tasks | |
| Replacement of DC Circuit Breakers | AMM 24-65-00-960-801 |
| Operational Test of the Stall Protection System (SPS) | AMM 27-32-00-710-801 |
| Functional Test of the Stall Protection System | AMM 27-32-00-720-801 |
| Removal of the Stall Protection Computer | AMM 27-32-01-000-801 |
| Installation of the Stall Protection Computer | AMM 27-32-01-400-801 |
| Removal of the Horizontal-Stabilizer-Trim Electronic-Control Unit (HST ECU) | AMM 27-41-21-000-801 |
| Installation of the Horizontal-Stabilizer-Trim Electronic-Control Unit (HST ECU) | AMM 27-41-21-400-801 |
| Operational Test of the Horizontal-Stabilizer-Trim Electronic-Control Unit (HST ECU) | AMM 27-41-21-710-801 |
| 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 |
| Operational Test of the Input/Output Concentrator Unit (IOC) | AMM 31-45-05-710-801 |
Troubleshooting Recommendations:
- Check the pilot's primary flight display and look for a failed stall flag next to the airspeed display. This verifies the system is not seeing the stall computer information.
- Pull the stall computer (R PWR) breaker CB2 - B10, reset after a couple seconds. This will re-boot the stall system computer.
- If fault is cleared after latency check has been completed, do close out.
- If fault remains, continue with next step.
- Re-rack SPCs.
- If system checks are good, do close out.
- If fault remains, continue with next step.
- Interchange IOCs.
- If system checks are good, do close out.
- If fault remains, continue with next step.
- Perform wiring check between R IOC and SPC.
- If system checks are good, do close out.
- If fault remains, continue with next step.
- Perform wiring check between R IOC and HST ECU.
- If system checks are good, do close out.
- If fault remains, continue with next step.
- Perform wiring check for power & grounds, and the R-GP-5 ARINC bus wiring for continuity and shorts to the shield between the stall computer, HST ECU, JB1 and JB2.
- If system checks are good, do close out.
- If fault remains, continue with next step.
- Replace SPC.
- If system checks are good, do close out.
- If fault remains, continue with next step.
- Replace HST ECU.
- Do close out.
