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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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03/23/22

Message Overview:

Message Name:

LVDT INVALID

Message Code:

B3-006885

Associated CAS:

STAB TRIM FAULT
(Advisory)

Reporting LRU: HORIZ TRIM LVDT1
System Description: 27-41-00
Schematic Diagram: 27-41-00
Wiring Diagram: 27-41-05

Message Description:

The Horizontal Stabilizer Electronic Control Unit (HST ECU) has detected an invalid LVDT 1.

Possible Causes:

  • Linear Variable-Differential Transformer (LVDT 1)
  • 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 (20501 - 20999)

Forum Articles/Infoservice/Newsletter: None

Pull the PRI STAB TRIM/RUD LIM circuit breaker CB1 - B15, and SEC STAB TRIM/RUD LIM circuit breaker CB2 - B13, reset after a couple seconds. This will re-boot the HST ECU.

60_lh_cbpnl60_rh_cbpnl

Quick Links:

Removal of the Covers and Plugs AMM 10-12-00-020-802
Installation of the Covers and Plugs AMM 10-12-00-420-801
Standard Aircraft Configuration for Maintenance AMM 12-00-00-867-803
Operational Test of the Pitch Trim System AMM 27-41-00-710-801
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 Position Sensor AMM 27-41-17-000-801
Installation of the Position Sensor AMM 27-41-17-400-801
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
Data Download from the Maintenance Diagnostic Computer (MDC) AMM 45-45-01-970-802
Safety Precautions - Maintenance Practices - ALL SPM 20-00-01-02-01
Wire Repair - Maintenance Practices - ALL SPM 20-12-10-02
Electrical Connectors - Maintenance Practice - ALL SPM 20-20-00-02-01

Troubleshooting Recommendations:

  1. Re-rig the pitch trim system.

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

  2. Check voltage at LVDT 1 pins 1 to 2. Excitation is 5 Volts RMS ± 1%.

    1. If voltage is out of tolerance, go to step 4.
    2. If voltage is within tolerance, continue with next step.

  3. Interchange LVDT 1 with LVDT 2.

    1. If fault follows the LVDT, replace faulty LVDT. Do close out.
    2. If fault remains, continue with next step.

  4. Do wiring checks between LVDT 1 and HST ECU. Repair as required.

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

  5. Replace HST ECU.
  6. Do close out.

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