02/26/21
Message Overview:
Message Description:
No Air Data Computer 1 (ADC-1) Input to Horizontal Stabilizer Electronic Control Unit (HST ECU) on L-GP-5.
Possible Causes:
- Air Data Computer (LH) (A1)
- Horizontal-Stabilizer-Trim Electronic-Control Unit (HST ECU) (A130)
- L Input/Output Concentrator (L IOC) (A4-IOC1)
- Associated Wiring
Troubleshooting Tips:
Advisory Wire/Service Bulletin:
- AW300-27-0081 - Spoiler Electronic Control Unit (SECU) and Horizontal Stabilizer Electronic Control Unit (HSTECU) - Cold Temperature Circuit Breaker Reset Procedure (20501 - 20999)
Forum Articles/Infoservice/Newsletter: None
Before troubleshooting this problem, reset HST ECU by pulling CB1-B15 & CB2-B13 and then resetting CBs with aircraft power on. Continue with troubleshooting if fault persists.
Before performing wiring checks all LRU (line replaceable units) must be removed from rack connectors. BD-100 Schematic Manual 31-45-00 page 21 will aid in the identification of all LRUs on L-GP-5 Bus.
Quick Links:
| 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 |
| 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:
- Perform ADC reversion to ADC #2 on cockpit reversionary select panel. (equivalent to swap ADCs).
- If system checks are good, do close out.
- If fault remains, continue with next step.
- Swap IOCs.
- If system checks are good, do close out.
- If fault remains, continue with next step.
- Do wiring check (data bus) between ADC1 and IAPS (L IOC).
- If system checks are good, do close out.
- If fault remains, continue with next step.
- Replace HST ECU.
- Do close out.