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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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03/02/21

Message Overview:

Message Name:

NO ADC MACH INPUT

Message Code:

B3-007960

Associated CAS:

STALL PROTECT FAIL
(Caution)

Reporting LRU: STALL COMPUTER
System Description: 27-32-00
Schematic Diagram: 27-32-00
Wiring Diagram: 27-32-01
34-13-05
34-13-09

Message Description:

No Mach number input data from both left and right Air Data Computer or SPC cross miscompare function fails.

Possible Causes:

  • Left Air Data Computer (A1)
  • Right Air Data Computer (A2)
  • Stall Protection Computer (SPC) (A178)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin:

  • AW300-27-0105 - "STALL PROTECT FAIL" Nuisance CAS Message (20501 to 20999)
  • AW300-27-34-0010 - Integrated Standby Instrument (ISI) Airspeed Indication Fluctuation & Potential STALL PROTECT FAIL and/or RUDDER LIMITER FAULT Messages (20501 - 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 - 20999)

Forum Articles/Infoservice/Newsletter: None

Potential airspeed fluctuations, 'STALL PROTECT FAIL' and 'RUDDER LIMITER FAULT' Crew Alerting System (CAS) messages may be experienced after the aircraft has been in heavy or extended rain in flight or on the ground.

To clear the 'STALL PROTECT FAIL' message that may be due to water ingestion, the following troubleshooting can be used:

CAUTION: ENSURE THE PROBES COVERS ARE REMOVED.

  1. Activate the probe heaters on ground with the following limitations: The probe heaters should not be activated on ground in still air for longer than 5 minutes.
  2. After five minutes, if the messages are still present, assume that water in the probe is not the cause of the failure.
  3. Visually inspect the probes for contamination that may be preventing proper operation of the probes. Refer to Aircraft Maintenance Manual (AMM) tasks for cleaning of the Pitot-Static Probe and cleaning of the Standby Pitot Probe.
  4. Water accumulation further in the line beyond the probe should also be considered if the fault does not clear. Visually inspect the drain tube for the pitot line per AMM to ensure that no moisture is present.

To clear the 'STALL PROTECT FAIL' message that may be due to water ingestion into the Pitot Probes, the procedure included in the AW300-27-34-0010 could be followed.

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 Air Data Computer AMM 34-13-01-000-801
Installation of the Air Data Computer AMM 34-13-01-400-801
Functional Test of the Air Data Computer AMM 34-13-01-720-801
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:

  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.

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

    AIR DATA 1 CB1-C1
    AIR DATA 2 CB2-C1
    STALL L PWR CB1-B10
    STALL R PWR CB2-B10

  2. Do wiring check of ARINC 429 L-ADC-6 data bus between SPC connector A178AP1 and the L ADC connector A1P1.

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

  3. Do wiring check of ARINC 429 R-ADC-6 data bus between SPC connector A178BP1 and the R ADC connector A2P1.

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

  4. Replace SPC.
  5. Do close out.

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