05/06/21
Message Overview:
Message Description:
Both channels of Data Concentrator Unit (DCU) are reporting the loss of Stall Protection Computer (SPC) channel B input.
Possible Causes:
- Stall Protection Computer (SPC) (A178)
- Data Concentrator Unit (DCU) (A14)
- Associated Wiring
Troubleshooting Tips:
Advisory Wire/Service Bulletin:
- AW300-27-0105 - "STALL PROTECT FAIL" Nuisance CAS Message (20501 to 20999)
- SB100-27-14 - Modification - Stall Protection System - Introduction of the Stall Protection Computer (SPC) Part No. 822-1792-003 to Correct Loopback ARINC 429 Failure Messages (20501 to 20999)
Forum Articles/Infoservice/Newsletter: None
Nuisance amber 'STALL PROTECT FAIL' caution CAS message may be posted at the end of the Stall Protection Computer (SPC) power-up or during the Stall Warning System Pilot Activated Test (PAT). This is the procedure to validate whether there is an actual system fault.
- If the 'STALL PROTECT FAIL' message appears after SPC power up, reset the SPC circuit breakers 'SPC CH A' (CBP1-B10) and 'SPC CH B' (CBP2-B10).
- If the message appears following a PAT, then reset the SPC circuit breakers 'SPC CH A' (CBP1-B10) and 'SPC CH B' (CBP2-B10). Perform another PAT and make sure the message does not come back.
If the 'STALL PROTECT FAIL' CAS message and associated cascading messages do not clear after performing the steps above, troubleshooting should be performed.
Quick Links:
| Operational Test of the Stall Protection System (SPS) | AMM 27-32-00-710-801 |
| 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 Data Concentrator Unit (DCU) | AMM 31-41-01-000-802 |
| Installation of the Data Concentrator Unit (DCU) | AMM 31-41-01-400-802 |
| 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 the following circuit breakers and perform the Pilot Activated Test (PAT) of the Stall Protection System on the Systems Test control-panel located on the center pedestal.
STALL L PWR CB1-B10 STALL R PWR CB2-B10 - If system checks are good, do close out.
- If fault remains, continue with next step.
- Do wiring check of ARINC 429 B-SPC-2 data bus from SPC connector A178BP1 to DCU connector A14DP1. Repair/replace as required.
- If system checks are good, do close out.
- If fault remains, continue to next step.
NOTE: An internal short of any LRU connected to this ARINC bus may cause the fault.
- Replace SPC.
- Do close out.