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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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Quick Links

10/10/24

Message Overview:

Message Name:

HORIZ TRIM BRAKE 3 FAULT

Message Code:

B3-006882

Associated CAS:

STAB TRIM FAULT
(Advisory)

Reporting LRU: HORIZONTAL STABILIZER TRIM ELECTRONIC CONTROL UNIT (HSTECU)
System Description: 27-41-00 - Pitch Trim System
Schematic Diagram: 27-41-00 - Pitch Trim System
Wiring Diagram: 27-41-01 - Pitch/Roll Trim Switch ALL
27-41-03 - Stab Trim Switch ALL
27-41-05 - Horizontal Stabilizer - Trim Actuator
27-41-13 - Motor Control Unit (MCU)
27-41-21 - Horizontal Stabilizer Trim Electronic Control Unit (HSTECU)
27-41-23 - Horizontal Stabilizer Trim Signal - ALL

Message Description:

The Horizontal Stabilizer Electronic Control Unit (HST ECU) has detected a Horizontal Trim Primary Brake 3 fault.

Possible Causes:

  • Horizontal Trim Primary Brake 3
  • Horizontal Trim Primary Motor
  • Horizontal-Stabilizer-Trim Electronic-Control Unit (HST ECU) (A130)
  • Motor Control Unit (MCU) (A131)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin:

  • AW300-27-0123 - No Fault Found Reduction Initiative and Trouble Shooting information – Spoiler Fault Cyan Message
  • AW300-27-0410 - “PRI STAB TRIM FAIL” EICAS message Troubleshooting

Forum Articles/Infoservice/Newsletter: None

Flight Operation Notifications Manual (FONM): None

NOTES:

  • If the pilot disconnects the autopilot with the MSW switch on the yoke and hits it more than 2 times in 1½ seconds this can cause the primary stab trim to fail. The clue that this happened is brake #1 and #3 are posted as the faults. This has happened several times and MOOG confirmed the issue. There also maybe possible if they hit the glareshield AP button more than once also.

Quick Links:

Operational Test of the Rudder Travel Limiter Actuator AMM 27-21-28-710-801
Electrical Rigging of the Rudder Travel Limiter Actuator AMM 27-21-28-820-801
Operational Test of the Pitch Trim System AMM 27-41-00-710-801
Functional Test of the Pitch Trim System AMM 27-41-00-720-801
Electrical Rigging of the Pitch Trim System AMM 27-41-00-820-801
Rigging Check of the Pitch Trim System AMM 27-41-00-220-801
Removal of the Motor and Brake Unit AMM 27-41-09-000-801
Installation of the Motor and Brake Unit AMM 27-41-09-400-801
Removal of the Motor Control Unit (MCU) AMM 27-41-13-000-801
Installation of the Motor Control Unit (MCU) AMM 27-41-13-400-801
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 Spoiler Electronic-Control Unit (SECU) AMM 27-61-05-000-801
Installation of the Spoiler Electronic-Control Unit (SECU) AMM 27-61-05-400-801
Electronic Rigging of the Spoiler Electronic-Control Unit (SECU) AMM 27-61-05-820-801
Electronic Rigging of the Spoiler Electronic-Control Unit (SECU) AMM 27-61-05-820-802
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. Pull the HST ECU breaker CB1 - B15, and CB2 - B13, reset after a couple seconds. This will re-boot the HST ECU. With hydraulics (L, Aux, R).
  2. To initiate the self-test of the HST ECU, perform the Operational Test of the Rudder Travel-Limiter Actuator. The HSTA Pre-Flight Brake Test is performed simultaneously with the RTL Pre-Flight Test, which is initiated via the SPC.
  3. Do wiring checks between HSTA secondary brake 3 and HST ECU. Repair as required.

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

  4. Check Brake 3 voltage (14 VDC) and resistance (32 to 34Ω).

    1. If voltage or resistance is within tolerance, go to step 6.
    2. If voltage or resistance is out of tolerance, continue with next step.

  5. Replace secondary motor.

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

  6. Perform the Functional Test of the Pitch Trim System to confirm system functionality.

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

  7. Replace HST ECU.

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

  8. Replace MCU.
  9. Do close out.

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