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(WARNING)
RED MESSAGE (CAUTION)
AMBER MESSAGE (ADVISORY)
CYAN MESSAGE (STATUS)
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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04/26/21

Message Overview:

Message Name:

NO TRIM AVAILABLE PITCH/ROLL TRIM SWITCH

Identifier: 274OBS001
Effectivity: AIRCRAFT 20501 - 20999
System: Flight Controls
Associated CAS: None
System Description: 27-41-00
Schematic Diagram: 27-41-00
Wiring Diagram: 27-41-01

Message Description:

Left or right yoke trim/roll switch does not trim "up" or "down" in primary or secondary mode.

Possible Causes:

  • L Pitch/Roll Trim Switch (S85)
  • R Pitch/Roll Trim Switch (S84)
  • Junction Box 3 (JB3)
  • Horizontal Stabilizer Trim Electronic Control Unit (HST ECU) (A130)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

The Pitch/Roll trim switch, being a sealed switch, cannot be cleaned and must be replaced if the switch is not functional.

Quick Links:

Removal of the Pitch/Roll Trim Switch AMM 27-41-01-000-801
Installation of the Pitch/Roll Trim Switch AMM 27-41-01-400-801
Operational Test of the Pitch/Roll Trim Switch AMM 27-41-01-710-801
Removal of the Junction Box JB3 AMM 24-63-09-000-802
Installation of the Junction Box JB3 AMM 24-63-09-400-802
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
Standard Practices - Wire Repair SPM 20-12-10-02

Troubleshooting Recommendations:

  1. Perform Operational Test of both the pilot and copilot trim switch.

    1. If one switch passes Operational Test, suspect the non-functional switch.
    2. If switch fails, remove and replace trim switch.
    3. If problem is still present continue with following steps.

  2. Perform wiring check for the appropriate control wheel per the following tables:

    Pilot Control Wheel From: To: Expected Results:
    Pilot Pitch Trim Nose DN P151 pin Y A130AP1B3 0 Ω
    Pilot Pitch Trim Nose UP P151 pin b A130AP1A3 0 Ω
    Pilot Pitch Trim Nose DN P151 pin z GS2153 0 Ω
    Pilot Pitch Trim Nose UP P151 pin c GS2153 0 Ω
    Copilot Control Wheel From: To: Expected Results:
    Copilot Pitch Trim Nose DN P150 pin m A130BP1B2 0 Ω
    Copilot Pitch Trim Nose UP P150 pin q A130BP1A2 0 Ω
    Copilot Pitch Trim Nose DN P150 pin n GS2150 0 Ω
    Copilot Pitch Trim Nose UP P150 pin r GS2150 0 Ω

  3. If any of the wiring checks fail, repair wiring and/or Junction Box 3.
  4. If problem still remains, replace HSTECU.
  5. Do close out.

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