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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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06/21/21

Message Overview:

Message Name:

Master Disconnect Switches are Defective

Message Code: 221OBS002
Effectivity: All
System: Autopilot System
System Description: 22-12-00
Schematic Diagram: 22-12-00 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Wiring Diagram: 22-11-00 [ Global Express ]  [ G5000 ]  [ Global XRS ]
22-12-00 [ Global Express ]  [ G5000 ]  [ Global XRS ]
27-32-00 [ Global Express ]  [ G5000 ]  [ Global XRS ]
27-41-00 [ Global Express ]  [ G5000 ]  [ Global XRS ]

Message Description:

Observed fault that the pilot's or the copilot's master-disconnect switch is defective. There are four sets of contacts in the switch. Two sets of contacts are for the stabilizer/pitch trim system and they are usually closed. One set is for the autopilot system and it is usually closed. The last set is for the stall protection system (SPS) stick pusher and it is usually open.

Possible Causes:

  • Copilot Master Disconnect Switch (S44)
  • Pilot Master Disconnect Switch (S45)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

Quick Links:

Removal of the Master Disconnect Switches AMM 22-12-17-000-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Installation of the Master Disconnect Switches AMM 22-12-17-400-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Operational Test of the Master Disconnect Switches AMM 22-12-17-710-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Opening of Non-Thermal Circuit Breakers AMM 24-00-00-863-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Closing of Non-Thermal Circuit Breakers AMM 24-00-00-863-802 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Electrical/Electronic Safety Precautions AMM 24-00-00-910-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Removal of the Junction Box JB4 AMM 24-00-05-000-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Installation of the Junction Box JB4 AMM 24-00-05-400-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Operational Test of the Stall Protection System-Dual Channel AMM 27-32-00-710-802 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Removal of the Stall Protection Computer AMM 27-32-01-000-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Installation of the Stall Protection Computer AMM 27-32-01-400-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Removal of the Stick Pusher Actuator AMM 27-32-17-000-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Installation of the Stick Pusher Actuator AMM 27-32-17-400-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Operational Test of the Horizontal-Stabilizer Trim System AMM 27-41-00-710-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Removal of the Flight-Control Units AMM 27-61-05-000-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Installation of the Flight-Control Units AMM 27-61-05-400-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Safety Precautions-Maintenance Practices SPM 20-00-01 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Wire Repair SPM 20-12-10 [ Global Express ]  [ G5000 ]  [ Global XRS ]

Troubleshooting Recommendations:

  1. Do the steps that follow to isolate master-disconnect switch related to autopilot disconnect. Disconnect the two master-disconnect switches at the terminal module in the control wheel. Do a continuity check on each master-disconnect switch between the pins that follow:
    NOTE: The pilot and copilot autopilot disconnect contacts are connected in series.

    PIN (wire color) PIN (wire color) CONTACTS
    A3 (blue) A2 (white) CLOSED
    B3 (violet) B2 (gray) CLOSED
    C3 (white/black) C2 (white/orange) CLOSED
    D4 (yellow) D1 (white/gray) OPEN

    Push and hold the master-disconnect switch and do a continuity check of the pins that follow:

    PIN (wire color) PIN (wire color) CONTACTS
    A3 (blue) A2 (white) OPEN
    B3 (violet) B2 (gray) OPEN
    C3 (white/black) C2 (white/orange) OPEN
    D4 (yellow) D1 (white/gray) CLOSED

    1. If the results of the continuity check is unsatisfactory, install a new master-disconnect switch and do close out.
    2. If the results of the continuity check is satisfactory, connect the master-disconnect switches and continue with the next step.

  2. Remove the junction box JB4 and do a continuity check between the ground stud GS194 and the connector JB4CP1 pin 1A as follows:

    • Push and hold one master disconnect switch and do the continuity check.
    • Check that the multimeter shows open circuit between the ground stud and the JB4 connector.
    • Release the master-disconnect switch and the multimeter shows continuity.
    • Push and hold the other master disconnect switch and do the continuity check again.
    • Check that the multimeter shows open circuit between the ground stud and the JB4 connector.
    • Release the master-disconnect switch and the multimeter shows continuity.

    1. If the results of the continuity check is satisfactory, do close out.
    2. If the results of the continuity check is unsatisfactory, do a wiring check at the control wheels, JB4, ground stud, terminal modules, and bulkhead connectors and repair or replace the defective associated wiring.

  3. Re-install JB4.
  4. Do the steps that follow to isolate the master-disconnect switch related to stabilizer/pitch trim disconnect. Disconnect the applicable master-disconnect switch at the terminal module in the control wheel. Do a continuity check on the master-disconnect switch between the pins that follow:

    PIN (wire color) PIN (wire color) CONTACTS
    A3 (blue) A2 (white) CLOSED
    B3 (violet) B2 (gray) CLOSED
    C3 (white/black) C2 (white/orange) CLOSED
    D4 (yellow) D1 (white/gray) OPEN

    Push and hold the master-disconnect switch and do a continuity check of the pins that follow:

    PIN (wire color) PIN (wire color) CONTACTS
    A3 (blue) A2 (white) OPEN
    B3 (violet) B2 (gray) OPEN
    C3 (white/black) C2 (white/orange) OPEN
    D4 (yellow) D1 (white/gray) CLOSED

    1. If the results of the continuity check is unsatisfactory, install a new master-disconnect switch and do to close out.
    2. If the results of the continuity check is satisfactory, connect the master-disconnect switch and continue with the next step.

  5. Remove the FCU 1 and FCU 2 to get access to the electrical connectors A65 and A66. Do a continuity check between the ground studs and the FCU 1 and FCU 2 connectors as follows:
    For the pilot master disconnect:

    Ground Stud (GS) FCU 1 FCU 2
    GS709 A65AP1 - pin 8G
    GS621 A66AP1 - pin 8G

    For the copilot master disconnect:

    Ground Stud (GS) FCU 1 FCU 2
    GS620 A65DP1 - pin 8D
    GS710 A66DP1 - pin 8D

    1. Push and hold the applicable master disconnect switch and do the continuity check.
    2. Check that the meter shows open circuits between the ground studs and the FCU connectors.
    3. Release the master-disconnect switch and the meter shows continuity.
    4. If the results of the continuity check is satisfactory, do the close out.
    5. If the results of the continuity check is unsatisfactory, do a wiring check at the control wheel, FCUs, ground studs, and bulkhead connectors and repair or replace the defective associated wiring.

  6. Install the FCU 1 and FCU 2.
  7. Do the steps that follow to isolate the master-disconnect switch related to SPS stick pusher disconnect. Disconnect the applicable master-disconnect switch at the terminal in the control wheel. Do a continuity check on the master-disconnect switch between the pins that follow:

    PIN (wire color) PIN (wire color) CONTACTS
    A3 (blue) A2 (white) CLOSED
    B3 (violet) B2 (gray) CLOSED
    C3 (white/black) C2 (white/orange) CLOSED
    D4 (yellow) D1 (white/gray) OPEN

    Push and hold the master-disconnect switch and do a continuity check of the pins that follow:

    PIN (wire color) PIN (wire color) CONTACTS
    A3 (blue) A2 (white) OPEN
    B3 (violet) B2 (gray) OPEN
    C3 (white/black) C2 (white/orange) OPEN
    D4 (yellow) D1 (white/gray) CLOSED

    1. If the results of the continuity check is unsatisfactory, install a new master-disconnect switch and do the close out.
    2. If the results of the continuity check is satisfactory, connect the master-disconnect switch and continue with the next step.

  8. Remove the SPS computer and disconnect the SPS stick pusher. Do a continuity check between the ground stud and the stick pusher as follows:
    For the pilot master disconnect:

    Ground Stud (GS) PUSHER
    GS194 A190P1 - pin P

    For the copilot master disconnect:

    Ground Stud (GS) PUSHER
    GS580 A190P1 - pin R

    1. Push and hold the master disconnect switch and do the continuity check.
    2. Check that the meter shows continuity between the ground stud and the pusher connector.
    3. Release the master-disconnect switch and the meter shows open circuit. If the results of the continuity check is satisfactory, do the close out.If the results of the continuity check is unsatisfactory, do a wiring check at the control wheel, pusher, ground stud, terminal modules and bulkhead connectors and repair or replace the defective associated wiring.
    4. If the results of the continuity check is satisfactory, do the close out.
    5. If the results of the continuity check is unsatisfactory, do a wiring check at the control wheel, pusher, ground stud, terminal modules and bulkhead connectors and repair or replace the defective associated wiring.

  9. Install the SPS computer and connect the SPS stick pusher.
  10. Do the close out.

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