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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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For AOG assistance contact:

CRC Montreal (YUL)
Quick Links

04/02/21

Message Overview:

Message Name:

GS CANCEL INVALID
(Service Message)

Message Code:

B3-642569

Associated CAS:

None

Reporting LRU: TAWS MARK V
System Description: 34-42-00
Schematic Diagram: 34-42-00
Wiring Diagram: 34-42-01

Message Description:

Glide Slope Switch stuck or discrete held low for 15+ seconds.

Possible Causes:

  • Terrain-Avoidance Warning System (TAWS) Computer (A34)
  • TAWS/Landing Gear Control-Panel (PL10)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

Quick Links:

Removal of the Terrain-Avoidance Warning System (TAWS) Computer AMM 34-42-01-000-801
Installation of the Terrain-Avoidance Warning System (TAWS) Computer AMM 34-42-01-400-801
Removal of the TAWS/LANDING GEAR Control-Panel AMM 34-42-09-000-801
Installation of the TAWS/LANDING GEAR Control-Panel AMM 34-42-09-400-801
Standard Practices - Replace Wiring SPM 20-12-00-02
Standard Practices - Repair Wiring SPM 20-12-10-02

Troubleshooting Recommendations:

  1. Reset TAWS (CB2-A6) circuit breaker or push in the TAWS TEST/RESET switch on the center pedestal.

    1. If system check passes, do close out.
    2. If fault remains, continue with next step.

  2. Operate the TAWS GS WARN Switch on the center pedestal and confirm it is operating as per drawing. Repair/replace as required.

    1. If system check passes, do close out.
    2. If fault remains, continue with next step.
      NOTE: When pushed in, the TAWS GS WARN switch will provide a ground, through a diode, at pin D9 of TAWS computer connector A34BP1.

  3. Replace the TAWS computer.
  4. Do close out.

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