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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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03/23/26

Message Overview:

Message Name:

LEFT SPC RELAY FAILED

Message Code:

B3-007127

Associated CAS:

L WINDOW HEAT FAIL
(Caution)

Reporting LRU: L WSHLD HEAT SPCC
System Description: 30-41-00 - Windshield And Side Window Anti-ice
Schematic Diagram: SSM 30-41-00-101 - Windshield and Side Window Anti-Ice
Wiring Diagram: WM 30-41-09 - Windshield Heater Power-Supply (LHS) - ALL

Message Description:

Left Window Secondary Power Center Relay has failed.

Possible Causes:

  • Relay (K65)
  • Left Side Window Temperature Controller (L WTC) (A159)
  • Left Secondary Power Center (LSPC) (A37)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin:

Alert Service Bulletin:

  • A100-30-03 - Special Check - Windshield and Side Window Anti-Ice - Torquing of Electrical Connections at Terminal Blocks TB3 and TB4; Ground Studs GS2269, GS2270, GS2273, and GS2274; Windshield Terminals G, H, L1, and L2; and Side Window Terminals P and G
    (20501 - 20999)

Full Throttle Blog/Forum Articles/Infoservice/Newsletter: None

Flight Operation Notifications Manual (FONM): None

NOTES:

  • The majority of L and R window Temperature Control circuits and parts (including relays) can be used for troubleshooting if needed (interchange).
  • The Windshield Temperature Controllers and Side Window Temperature Controllers are different part numbers.

Quick Links:

General Setup for Maintenance
Standard Aircraft Configuration for Maintenance AMM 12-00-00-867-803
Connect Electrical Power to the Aircraft AMM 24-00-00-861-801
Remove Electrical Power from the Aircraft AMM 24-00-00-861-802
Electrical/Electronic Safety Precautions AMM 24-00-00-910-801
Electrostatic Discharge Safety Precautions AMM 24-00-00-910-802
Maintenance Tasks
Removal of the Secondary Power Center (SPC) AMM 24-62-01-000-801
Installation of the Secondary Power Center (SPC) AMM 24-62-01-400-801
Removal of the Secondary Power Center (SPC) Relays AMM 24-62-04-000-801
Installation of the Secondary Power Center (SPC) Relays AMM 24-62-04-400-801
Operational Test of the Side-Window Anti-Ice System AMM 30-41-00-710-802
Removal of the Side-Window Temperature Controller AMM 30-41-05-000-801
Installation of the Side-Window Temperature Controller AMM 30-41-05-400-801

Troubleshooting Recommendations:

  1. Do the AMM task "30-41-00-710-802 - Operational Test of the Side-Window Anti-Ice System".
  2. Are the results satisfactory?

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

  3. Interchange Left Side Window Power Relay (K65) and Right Side Window Power Relay (K66).
  4. Does the fault "B3-007127 - Left SPC Relay Failed" remain posted?

    1. If YES, continue with the next step.
    2. If NO, replace defective Side Window Power Relay and do close out.

  5. Ensure Left WSHLD/WINDOW PBA (SDS41) is selected ON.
  6. Measure 28 VDC at Left Side Window Temperature Controller (SWTC) A159P1 pin B.
  7. Is the 28 VDC present?

    1. If YES, go to step 9.
    2. If NO, continue with the next step.

  8. Check continuity between L SWTC (A159) and L SPC (A37) as per table below:

    From To Expected Result Result
    A159P2 - B A37P2 - Y Continuity
    A159P1 - K A37P1 - 7 Continuity

    1. If wiring check satisfactory, continue with next step
    2. If wiring check is not satisfactory, repair wiring and do close out.

  9. Measure 28 VDC at Left Side Window Temperature Controller (SWTC) A159P1 pin U.
  10. Is the 28 VDC present?

    1. If YES, go to step 15.
    2. If NO, continue with the next step.

  11. Interchange the Left WSHLD/WINDOW PBA (SDS41) with Right WSHLD/WINDOW PBA (SDS42).
  12. Does the fault "B3-007127 - Left SPC Relay Failed" remain posted?

    1. If YES, continue with the next step.
    2. If NO, replace defective WSHLD/WINDOW PBA.

  13. Do wiring checks between Anti-Ice Panel (PL19) and Left SWTC(A159) and L SPC (A37). Repair as required.

    From To Expected Result Result
    PL19P1-V A159P1-U Continuity
    PL19P1-Y A37P1-26 Continuity

    1. If wiring check satisfactory, continue with next step
    2. If wiring check is not satisfactory, repair wiring and do close out.

  14. Does the fault "B3-007127 - Left SPC Relay Failed" remain posted?

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

  15. Interchange Left Side Window Temperature Controller (SWTC) (A159) with Right Side Window Temperature Controller (SWTC) (A160).
  16. If the fault follows the SWTC replace defective Side Window Temperature Controller (SWTC). If fault remain, replace Left Secondary Power Center (L SPC).
  17. Do close out.

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