10/10/24
Message Overview:
Message Name:
HORIZ TRIM BRAKE 1 FAULT
Message Code:
B3-006881
Associated CAS:
| 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 |
Message Description:
The Horizontal Stabilizer Electronic Control Unit (HST ECU) has detected a Horizontal Trim Primary Brake 1 fault.
Possible Causes:
- Horizontal Trim Primary Brake 1
- Horizontal Trim Primary Motor
- Horizontal-Stabilizer-Trim Electronic-Control Unit (HST ECU) (A130)
- Motor Control Unit (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:
- 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).
- 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.
- If system checks are good, do close out.
- If fault remains, continue with next step.
- Do wiring checks between HSTA primary brake 1 and HST ECU. Repair as required.
- If system checks are good, do close out.
- If fault remains, continue with next step.
- Perform the Functional Test of the Pitch Trim System to confirm system functionality.
- If system checks are good, do close out.
- If fault remains, continue with next step.
- Replace HST ECU.
- If system checks are good, do close out.
- If fault remains, continue with next step.
- Replace MCU.
- Do close out.
