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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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01/28/21

Message Overview:

NWS LIMIT EXCEEDED
(Caution)

DDG Reference: None
Pilot Action (QRH): GEAR 10-7
System Description: 32-51-00
Schematic Diagram: 32-51-00
Wiring Diagram: 32-61-05

Message Description:

The amber 'NWS LIMIT EXCEEDED' caution CAS message indicates that the NWS Overtow Switch has been tripped (i.e. NLG rotated over 120°, left or right, or manually tripped by accident), OR there is a failure of the NWS LIMIT PSEU discrete input.

If the NWS angle is over 65°, left or right, when the NWS PBA is switched on, an amber 'NWS FAIL' Caution CAS message will be displayed and an SCU Fault Code 'U' will appear on the SCU 7-segment display. See the 'SCU Fault Code 'U' for additional instructions.

Possible Causes:

  • Nose Landing Gear (NLG) rotated out of limits
  • Nose Wheel Steering (NWS) Overtow Switch
  • Proximity-Sensor Electronic Unit (PSEU) (A9)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin:

  • AW300-32-0263 - Nose Landing Gear Overtow Switch Inadvertently Tripped

Forum Articles/Infoservice/Newsletter: None

Quick Links:

General Visual Inspection after the Nose Landing Gear (NLG) Exceeds the Tow Limits AMM 05-51-23-210-801
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
Removal of the Nose Gear Steering and Sensor Harness No. 1 AMM 32-21-09-000-801
Installation of the Nose Gear Steering and Sensor Harness No. 1 AMM 32-21-09-400-801
Removal of the Nose Gear Steering and Sensor Harness No. 2 AMM 32-21-09-000-802
Installation of the Nose Gear Steering and Sensor Harness No. 2 AMM 32-21-09-400-802
Standard Practices - Replace Wiring SPM 20-12-00-02
Standard Practices - Repair Wiring SPM 20-12-10-02

Troubleshooting Recommendations:

  1. Visually inspect if the Overtow Switch is tripped.

    1. If the Overtow switch is tripped, perform the General Visual Inspection after the Nose Landing Gear (NLG) Exceeds the Tow Limits (AMM TASK 05-51-23-210-801).
    2. If the Overtow Switch is not tripped, continue troubleshooting.

  2. Remove PSEU.
  3. Check for continuity per the following table:

    From To Expected Results Actual Results
    A9AP1 (PSEU) PIN 13K GND OPEN (∞Ω)

    1. If there is continuity, replace PSEU.
    2. If there is no continuity, go to next step.

  4. Check wiring for continuity per the following table:

    From To Expected Results Actual Results
    A9AP1 (PSEU) PIN 13K J164 pin J CONTINUITY
    J164 PIN H GND CONTINUITY

    1. If there is no continuity, repair wiring as required.
    2. If there is continuity, replace Overtow switch.

  5. Do close out.

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