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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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CRC Montreal (YUL)
Quick Links

10/25/19

Message Overview:

Message Name:

STAIR LIGHTS UNSERVICEABLE

Message Code: 332OBS003
Effectivity: All
System: Passenger Compartments Entrance Area Lighting System
System Description: 33-20-00
Schematic Diagram: 33-21-00 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Wiring Diagram: 33-21-01 [ Global Express ]  [ G5000 ]  [ Global XRS ]

Fault Description:

Stair Light does not come ON.

Possible Causes:

  • Stair Light Bulb
  • Door Stair Light Top Folding (DS16)
  • Stair Light Step 1 (DS17)
  • Stair Light Step 2 (DS18)
  • Stair Light Step 3 (DS19)
  • Stair Light Step 4 (DS20)
  • Stair Light Step 5 (DS21)
  • Stair Light Step 6 (DS22)
  • Stair Light Lower Folding Step Forward (DS23)
  • Stair Light Lower Folding Step After (DS24)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

NOTE: If all the stair lights do not come on, the door switch (S18), the stair light switch (S21), or the stair lights circuit breaker (B3) can be defective.

Quick Links:

Electrical/Electronic Safety Precautions AMM 24-00-00-910-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Removal of the Door Stair Lights AMM 33-21-01-000-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Installation of the Door Stair Light AMM 33-21-01-400-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Replacement of the Door Stair Light-Bulb AMM 33-21-01-960-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Operational Test of the Door Stair Lights AMM 33-21-01-710-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Removal of the External Avionics-Compartment Access-Panel (140BB) AMM 52-45-11-000-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Installation of the External Avionics-Compartment Access-Panel (140BB) AMM 52-45-11-400-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Safety Precautions - Maintenance Practices - ALL SPM 20-00-01-02 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Wire Repair - Maintenance Practices - ALL SPM 20-12-10-02 [ Global Express ]  [ G5000 ]  [ Global XRS ]

Troubleshooting Recommendations:

  1. Replace the applicable door stair light-bulb and check if the applicable light come on.

    1. If system checks are good, do close out.
    2. If fault remains, continue with next step.

  2. Check for 28 VDC between the splices of the stair lights and ground as follow:

    Stair Lights From To Expected Result Result
    DS16 SP987 Ground 28 VDC
    DS17 SP989 Ground 28 VDC
    DS18 SP991 Ground 28 VDC
    DS19 SP993 Ground 28 VDC
    DS20 SP995 Ground 28 VDC
    DS21 SP997 Ground 28 VDC
    DS22 SP655 Ground 28 VDC
    DS23 SP655 Ground 28 VDC
    DS24 SP655 Ground 28 VDC

    1. If there is no 28 VDC between the applicable stair light and ground, repair or replace the defective wiring as required and do close out.
    2. If there is 28 VDC between the applicable stair light and ground, continue with next step.

  3. Replace the defective stair light.
  4. Do close out.
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