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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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11/04/24

Message Overview:


Message Name:

WOW GEAR-UP DISAG FAULT [AT]

Message Code:

B3-682646

Associated CAS:

AT FAIL
(Advisory)

Reporting LRU: Autothrottle (AT) Computer
Effectivity: Post SB350-22-002
Aircraft 20937 and Subs
System Description: 22-30-00 - Auto Throttle System (ATS)
Schematic Diagram: 22-30-00-801 - Auto Throttle System (ATS)
32-61-00-101 - Position Indication System
Wiring Diagram: 22-30-00 - Auto Throttle System (ATS)
32-61-01 - Main-Landing-Gear Proximity Sensors (LHS) - ALL
32-61-03 - Main-Landing-Gear Proximity Sensors (RHS) - ALL
32-61-05 - Nose-Landing-Gear Proximity Sensors - ALL
32-61-09 - Proximity-Sensor Electronic Unit (PSEU) - ALL
32-61-12- Proximity-Sensor Electronic Unit (Power) - ALL

Message Description:

The "WOW Gear-Up Disag Fault" is posted if the Gear Down discrete input reports Gear Up (Open), but the Weight-On-Wheels discrete input reports On-Ground (Grounded) for 5 seconds continuously.

Possible Causes:

  • AT Computer (A252)
  • PSEU (A9)
  • Associated Wiring

Troubleshooting Tip:

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

NOTE: Review the Autothrottle "AT Diagnostic Information", to find details about the MDC Data Reader Labels & bits.
NOTE: Bombardier recommends referencing the elements one (1) through eleven(11) of the "Wiring & Connections" Troubleshooting Tip document. The intent of the document is to ensure the Maintenance Technician has the information needed to perform a comprehensive check of an aircraft system wiring circuit, while also doing checks found in the From - To tables called out in the Troubleshooting Recommendations element.

From - To Table (Example)
From To Expected Results Results
XXXX-XX XXXX-XX Continuity

Quick Links:

Standard Aircraft Configuration for Maintenance AMM 12-00-00-867-803
Removal of the Auto Throttle Computer AMM 22-30-01-000-801
Installation of the Auto Throttle Computer AMM 22-30-01-400-801
Functional Test of the Auto Throttle Computer AMM 22-30-01-720-801
Operational Test of the Proximity Sensors AMM 32-61-00-710-801
Functional Test of the Proximity Sensors AMM 32-61-00-720-801
Adjustment of the Proximity Sensors AMM 32-61-00-820-801
Removal of the Main Landing-Gear (MLG) Proximity-Sensors AMM 32-61-01-000-801
Installation of the Main Landing-Gear (MLG) Proximity-Sensors AMM 32-61-01-400-801
Removal of the Nose Landing-Gear (NLG) Proximity-Sensors AMM 32-61-05-000-801
Installation of the Nose Landing-Gear (NLG) Proximity Sensors AMM 32-61-05-400-801
Removal of the Proximity-Sensor Electronic Unit (PSEU) AMM 32-61-09-000-801
Installation of the Proximity-Sensor Electronic Unit (PSEU) AMM 32-61-09-400-801
Functional Test of the Proximity-Sensor Electronic Unit (PSEU) AMM 32-61-09-720-801
Functional Test of the Proximity-System Electronic-Unit Circuitry AMM 32-61-09-720-802
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. Using the MDC, navigate to Current Faults, check for CAS or MDC Faults associated with proximity sensors for the Gear Position & WoW. Resolve active CAS & MDC Faults associated with the Gear Position or WoW prior to starting this troubleshooting. Reference prox sensors below.

    MLG Down & Locked
    Sensor Name Sensor ID
    RGDLK1 PX08
    RGDLK2 PX38
    LGDLK1 PX09
    LGDLK2 PX39

    MLG UP & Locked

    2. Sensor Name Sensor ID
    RGUPLK PX04
    LGUPLK PX05
    MLG WOW Sensors
    Sensor Name Sensor ID
    RGWOW1 PX01
    RGWOW2 PX31
    LGWOW1 PX02
    LGWOW2 PX32

  2. Does the MDC Fault (WOW GEAR-UP DISAG FAULT) clear once Prox Sensor issues are resolved?

    1. If YES, do close out.
    2. If NO, continue next step.

  3. Using the MDC, navigate to the Maintenance Main Menu > LRU TEST > PSEU. Look for a prox sensor status that may be causing the WoW/GEAR-UP Disagree fault.
  4. Are any Prox Sensor issues shown in MDC?

    1. If YES, repair as required.
    2. If NO, continue next step.

  5. Do a wiring check as follows.
    NOTE: Refer to the "Wiring & Connections" document found in the Troubleshooting Tips element of this page.

    From To Results
    AT Computer A252P1-17 JB2DP1-E10
    AT Computer A252P1-10 PSEU A9CP1-D5

  6. Are wiring checks satisfactory?

    1. If YES, continue next step.
    2. If NO, repair wiring and do close out.

  7. The aircraft configuration must be in a WoW condition & MLG Down & Locked. Remove the Auto Throttle (AT) computer. Do a wiring check as follows.
    NOTE: Refer to the "Wiring & Connections" document found in the Troubleshooting Tips element of this page.

    From To Expected Results Results
    AT Computer A252P1-17 GND Continuity
    AT Computer A252P1-10 GND Continuity

  8. Are wiring checks satisfactory?

    1. If YES, continue next step.
    2. If NO, repair wiring. Do close out.

  9. Is the Fault (WOW GEAR-UP DISAG FAULT) persistent?

    1. If YES, replace Auto Throttle Computer and do close out.
    2. If NO, continue next step.

  10. Replace PSEU.
  11. Do close out.

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