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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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02/02/21

Message Overview:

Message Name:

CH A&B FAULT

Message Code:

B3-006825

Associated CAS:

R BLEED FAIL
(Caution)

Reporting LRU: HOT AIR T SNSR
System Description: 21-61-00
Schematic Diagram: 21-61-00
Wiring Diagram: 21-61-29

Message Description:

Both channels of the HOT AIR TEMPERATURE SENSOR are detected failed. Check for sensor failure.

Possible Causes:

  • Hot Air Temperature Sensor (HATS) (MT27)
  • Integrated Air System Controller 1 (IASC1) (A55)
  • Integrated Air System Controller 2 (IASC2) (A56)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

Quick Links:

Removal of the Hot Air Temperature-Sensor AMM 21-61-29-000-801
Installation of the Hot Air Temperature-Sensor AMM 21-61-29-400-801
Operational Test of the Bleed Air System AMM 36-11-00-710-801
Standard Practices - Replace Wiring SPM 20-12-00-02
Standard Practices - Wire Repair SPM 20-12-10-02

Troubleshooting Recommendations:

  1. Reset the PRESS 1 / PACK circuit breaker CB1-D14, the L WING / BLD LK circuit breaker CB1-E10 and the PRESS 2 / TRIM circuit breaker CB2-D14.

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

  2. Swap IASCs.

    1. If only Channel A Fault is shown, troubleshoot with B3-006826.
    2. If only Channel B Fault is shown, troubleshoot with B3-006827.
    3. If fault remains, continue with next step.

  3. Do wiring check between IASC1 A55P3 (pins 17 & 18) and HATS MT27 (pins 1 & 3). Repair as required.

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

  4. Do wiring check between IASC2 A56P1 (pins 48 & 65) and HATS MT27 (pins 4 & 6). Repair as required.

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

  5. Replace HATS sensor (or Swap with Pack Inlet Temperature Sensor MT25).
  6. Do close out.

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