TRIM AIR FAIL
(Caution)

The amber 'TRIM AIR FAIL' caution CAS message indicates a hot air regulating valve has failed, or a cabin / cockpit duct temp sensor is out of range.

• Hot Air Regulating-and-Shut Off Valve failure occurs when the valve remains full closed when commanded open (confirmation time 7s - CBIT and PBIT active). And when the valve remains full open when commanded closed (confirmation time 7 seconds - CBIT and PBIT active)
• When detected, the IASC 2 sends an amber 'TRIM AIR FAIL' message is displayed on the EICAS.
• A failure is detected with the cockpit or cabin duct temp sensor and is out of range, (-55°C or > 300°C).

• Hot Air Regulating and Shut-off Valve 1 (HARSOV 1 - Cockpit) (MPE5)
• Hot Air Regulating and Shut-off Valve 2 (HARSOV 2 - Cabin) (MPE6)
• Cabin Duct Temperature Sensor (Cabin DTS) (MT26)
• Cockpit Duct Temperature Sensor (Cockpit DTS) (MT35)

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

1. Interrogate the MDC as follows:
2. On the cursor control panel, ensure the toggle switch is to the right and select Anti-Ice, ECS and Fuel buttons simultaneously. The MDC main menu should now be displayed on Display Unit #3.
3. Using the joystick, select Current Faults (if the fault is active) or Aircraft History to research stored faults. From Aircraft History you can then select Fault Message History and locate the air condition fault logged.
4. Select the MDC fault from the drop down below to provide additional information to assist in troubleshooting.
   Select an MDC Fault Code/Message:B3-006662 - CH A&B FAULT [CKPT DUCT T SNSR]B3-006665 - CH A&B FAULT [CAB DUCT T SNSR]B3-006851 - DISAGREE / VALVE CLOSED [HOT AIR REG SOV1]B3-006852 - DISAGREE / VALVE OPEN [HOT AIR REG SOV1]B3-006853 - DISAGREE / VALVE CLOSED [HOT AIR REG SOV2]B3-006854 - DISAGREE / VALVE OPEN [HOT AIR REG SOV2]B3-007330 - CH A&B FAULT [PK DISCH T SNSR]