02/26/21
Message Overview:
Message Description:
Horizontal Stabilizer Electronic Control Unit (HST ECU) failure, possible internal memory or processor problem.
Consequently the failures described above will trigger in the MDC the corresponding Label 352 bit 14.
Possible Causes:
- Horizontal-Stabilizer-Trim Electronic-Control Unit (HST ECU) (A130)
- Associated Wiring
Troubleshooting Tips:
Advisory Wire/Service Bulletin:
- AW300-27-0077 - Troubleshooting Guide for Spoiler Electronic Control Unit and Horizontal Stabilizer Trim Electronic Control Unit
- AW300-27-0315 - PRI STAB TRIM FAIL EICAS message caused by CPLD U27
Forum Articles/Infoservice/Newsletter: None
Quick Links:
| 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 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 Input/Output Concentrator Unit (IOC) | AMM 31-45-05-000-801 |
| Installation of the Input/Output Concentrator Unit (IOC) | AMM 31-45-05-400-801 |
| Operational Test of the Input/Output Concentrator Unit (IOC) | AMM 31-45-05-710-801 |
| 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:
- Pull the HST ECU breaker CB1 - B15 and breaker CB2 - B13, reset after a few seconds. This will re-boot the HSTECU. Is the fault still present?
- If YES, continue with next step.
- If NO, do close out.
- Set aircraft power to OFF.
- Remove the HSTECU from the avionics rack (LHS).
- Set aircraft power ON.
- Perform a 28 VDC and ground check at the HSTECU as follows:
From To Expected Result Result A130CP1-5P Ground 28 VDC A130CP1-4K Ground 28 VDC A130CP1-4P Ground Continuity A130CP1-4J Ground Continuity - If power and ground are present as per table above, continue with next step.
- If power or ground are missing, investigate wiring and power source and rectify as required.
- Perform a wiring check on the wiring segments below, per electrical wiring diagrams:
- To Trim disconnect switches from HSTECU.
- To engage relay per electrical wiring diagram.
- To MCU from HSTECU.
- Check Autopilot trim enable wiring to HSTECU (if fault is with Autopilot engaged).
- From SECU to HSTECU (if fault is with spoiler trimming).
- From FCU to HSTECU (if fault is with flap trimming).
- If wiring defects are found, repair defective wiring as required and do close out.
- If wiring checks are good, continue with next step.
- Replace the HSTECU.
- Do close out.