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(WARNING)
RED MESSAGE (CAUTION)
AMBER MESSAGE (ADVISORY)
CYAN MESSAGE (STATUS)
WHITE MESSAGE Require immediate crew attention. These messages are accompanied by flashing master warning, triple chime attenson with or without voice message or dedicated tone. Require immediate crew awareness and future crew action may be required in the form of alternate system selection or performance limitation. These message are accompanied by flashing master caution and a single chime. Indicate safe or normal system operation which require crew awareness, over and above the dark cockpit philosophy. Indicate minor failures or reduction in systems capability, which require no crew action.

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05/06/21

Message Overview:

Message Name:

NO A-SPC-2 BUS OUTPUT

Message Code:

B3-007951

Associated CAS:

STALL PROTECT FAIL
(Caution)

L STALL SHAKER FAIL
(Advisory)

Reporting LRU: STALL COMPUTER
System Description: 27-32-00
Schematic Diagram: 27-32-00
Wiring Diagram: 27-32-05

Message Description:

Both channels of Data Concentrator Unit (DCU) are reporting the loss of Stall Protection Computer (SPC) channel A 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 (20003 - 20328)

Forum Articles/Infoservice/Newsletter: None

Nuisance CAS message 'STALL PROTECT FAIL' (amber) 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:

  1. 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

    1. If system checks are good, do close out.
    2. If fault remains, continue with next step.

  2. Do wiring check of ARINC 429 A-SPC-2 data bus from SPC connector A178AP1 to DCU connector A14DP1. Repair/replace as required.

    1. If system checks are good, do close out.
    2. If fault remains, continue to next step.
      NOTE: An internal short of any LRU connected to this ARINC bus may cause the fault.

  3. Replace SPC.
  4. Do close out.

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