STAB TRIM FAULT
(Advisory)

There is a minor failure causing a loss of redundancy in the horizontal stabilizer trim system.

• Displayed when there is a disagreement between Primary Stab Trim Channel and/or Pitch Trim Select switch position and/or Secondary 1(2) Validity signals.
• CAS Inhibited during take-off and landing conditions.
• Inhibited if any of the Left or Right Main Essential buses are NOT powered.
• The stabilizer trim will continue to function.

• Horizontal Stab Trim Electronic Control Unit (HSTECU) (A130)
• Pitch Trim/Stab Select Switch (S83) [Trim/Stall Panel - PL26]
• Input/Output Concentrator (IOC) [IAPS- A4]
• Horizontal Stabilizer Linear Variable Differential Transformer 1 (LVDT) [HSTA - MPE44]
• Horizontal Stabilizer Linear Variable Differential Transformer 2 (LVDT) [HSTA - MPE44]
• Primary Engage Relay K44 [DCPC - A35]
• Secondary Engage Relay K45  [DCPC - A36]
• Motor Control Unit  (MCU) (A131)
• Associated Wiring

Advisory Wire/Service Bulletin:

• AW300-27-0077 - Troubleshooting Guide for Spoiler Electronic Control Unit and Horizontal Stabilizer Trim Electronic Control Unit
• AW300-27-0086 - SPOILERS FAULT - Ailerons Not Centered on Power-Up
• AW300-27-0081 - Spoiler Electronic Control Unit (SECU) and Horizontal Stabilizer Electronic Control Unit (HST ECU) - Cold Temperature Circuit Breaker Reset Procedure
• AW300-27-0388 - Horizontal Stabilizer Trim Uncommanded Motion

Forum Articles/Infoservice/Newsletter: None

NOTES: 

• If the following cascading CAS messages post at the same time this is likely caused by each system not receiving a single input. Switch to Flight Control synoptic page and check for any abnormal indications for each system. 
  STAB TRIM FAULT (Advisory)
  FLAPS FAULT (Advisory)
  SPOILERS FAULT (Advisory)

• If all or any combination of the following CAS are posted at the same time Troubleshoot the PROX SYS Fault (Advisory) first.
  PROX SYS FAULT (ADVISORY)
  STAB TRIM FAULT (ADVISORY)
  SPOILERS FAULT (ADVISORY)
  L ENGINE FAULT (ADVISORY)
  R ENGINE FAULT (ADVISORY)
  

1. Interrogate the MDC as follows:

   1. On the cursor control panel, ensure the toggle switch is to the right and select Anti-Ice, ECS and Fuel buttons simultaneously. The MDC main menu should now be displayed on Display Unit #3.
   2. Using the joystick, select Current Faults (if the fault is active) or Aircraft History to research stored faults. From Aircraft History you can then select Fault Message History and locate the fault. Going into advanced diagnostics will provide an equation id for the fault identified.
   3. Select the MDC fault or equation from the drop down below to provide additional information to assist in troubleshooting.
      Select an MDC Fault Code/Message:B3-006855 - SPC CHANNEL A INPUT [HORIZ TRIM ECU]B3-006856 - SPC CHANNEL B INPUT [HORIZ TRIM ECU]B3-006858 - INTERNAL FAULT [HORIZ TRIM ECU]B3-006859 - NO L-GP-5 BUS INPUT [HORIZ TRIM ECU]B3-006860 - NO R-GP-5 BUS INPUT [HORIZ TRIM ECU]B3-006861 - NO HSTECU-1 BUS TO L-IOC [HORIZ TRIM ECU]B3-006862 - NO HSTECU-2 BUS TO R-IOC [HORIZ TRIM ECU]B3-006863 - PILOT MAN TRIM SW [HORIZ TRIM ECU]B3-006864 - COPILOT MAN TRIM SW [HORIZ TRIM ECU]B3-006865 - NO ADC-1 INPUT ON L-GP-5 [HORIZ TRIM ECU]B3-006866 - NO ADC-2 INPUT ON R-GP-5 [HORIZ TRIM ECU]B3-006867 - NO FGC-1 INPUT ON L-GP-5 [HORIZ TRIM ECU]B3-006868 - NO FGC-2 INPUT ON R-GP-5 [HORIZ TRIM ECU]B3-006869 - NO FCU INPUT ON L-GP-5 [HORIZ TRIM ECU]B3-006870 - NO FCU INPUT ON R-GP-5 [HORIZ TRIM ECU]B3-006873 - NO PSEU CHANNEL A INPUT [HORIZ TRIM ECU]B3-006874 - NO PSEU CHANNEL B INPUT [HORIZ TRIM ECU]B3-006879 - SECU-1 INPUT [HORIZ TRIM ECU]B3-006880 - SECU-2 INPUT [HORIZ TRIM ECU]B3-006881 - HORIZ TRIM BRAKE 1 FAULT [HORIZ TRIM BRAK1]B3-006882 - HORIZ TRIM BRAKE 3 FAULT [HORIZ TRIM BRAK3]B3-006885 - LVDT INVALID [HORIZ TRIM LVDT1]B3-006886 - LVDT INVALID [HORIZ TRIM LVDT2]B3-006887 - OPEN/SHORT MOTOR [H-TRIM PRIM MOTR]