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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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For AOG assistance contact:

CRC Montreal (YUL)
Quick Links

02/02/21

Message Overview:

Message Name:

DISAGREE / VALVE CLOSED

Message Code:

B3-006853

Associated CAS:

TRIM AIR FAIL
(Caution)

Reporting LRU: HOT AIR REG SOV2
System Description: 21-52-00
Schematic Diagram: 21-61-00
Wiring Diagram: 21-61-05

Message Description:

The Cabin Hot Air Regulating and Shut-off Valve (HARSOV2) is detected failed in CLOSED position.

Possible Causes:

  • Cockpit Hot Air Regulating and Shut-off Valve (HARSOV2)
  • Integrated Air System Computer (IASC 2) (A56)
  • Junction Box 1 (JB1)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

HARSOV position can be monitored via IAC LRU Test Page

  • Select IASC 2A and go to the Air Conditioning Raw Data Page
  • Select Air Conditioning Valve Status to view HARSOV position

NOTE: Select "TRIM AIR ONLY" on the AIR COND / BLEED panel, the HARSOVs are fully open. HOT AIR REG SOV 1 and 2 should both go from FULL CLOSED/NOT FULL OPEN to NOT FULL CLOSED/FULL OPEN within 6 to 7 seconds.

Quick Links:

Removal of the Integrated Air System (IAS) Controller AMM 21-31-01-000-801
Installation of the Integrated Air System (IAS) Controller AMM 21-31-01-400-801
Removal of the Hot-Air Regulating-and-Shutoff Valve AMM 21-61-05-000-801
Installation of the Hot-Air Regulating-and-Shutoff Valve AMM 21-61-05-400-801
Standard Practices - Replace Wiring SPM 20-12-00-02
Standard Practices - Wire Repair SPM 20-12-10-02

Troubleshooting Recommendations:

  1. Do wiring checks between IASC2, HARSOV2 and ground.

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

  2. Swap HARSOVs.

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

  3. Swap IASCs.
  4. Do close out.

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