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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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01/24/23

Message Overview:

Message Name:

COLD CABIN/COCKPIT TEMPERATURE AND FCV CLOSED

Identifier: 216OBS002
Effectivity: AIRCRAFT 20501 - 20999
System: Air Conditioning
Associated CAS: None
System Description: 36-11-00 - Intermediate Pressure Bleed Air System
Schematic Diagram: 21-51-00 - Filtering and Flow Control System
21-61-00 - Temperature Control and Indication
Wiring Diagram: 21-61-21 - Cabin Ventilated Temperature-Sensor
21-61-25 - Flight-Compartment Ventilated Temperature-Sensor

Message Description:

A drift of a Differential Pressure Sensor (DPS) MT23 and MT24 may cause a Flow Control Valve (FCV) to close without any Engine Indication and Crew Alerting System (EICAS) message.

  1. Decrease of the temperature.
  2. Flow Control Valve (FCV) closed and amber on the Environmental Control System (ECS) synoptic page.
  3. Fault pointing out a "FCV Switch disagree" recorded in the Maintenance Diagnostic Computer (MDC) Fault History.

The Integrated Air System Controller (IASC) is unable to detect a drift of a DPS or a leak of the pressure lines of the DPS, the IASC then forces the FCV to close, this is a normal condition. The "DISAGREE/VALVE CLOSED" in the MDC Faults is misleading and only suspects a FCV Failed closed. The IASC does not send any EICAS Message as there is no action from the Pilots and it is not a performance issue.

Possible Causes:

  • Bleed Pressure Sensor 1 (MT21)
  • Bleed Pressure Sensor 2 (MT22)
  • Pressure Differential Sensor 1 (MT23)
  • Pressure Differential Sensor 2 (MT24)

Troubleshooting Tips:

Advisory Wire/Service Bulletin:

Forum Articles/Infoservice/Newsletter: None

Flight Operation Notifications Manual (FONM): None

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 Differential Pressure Sensor AMM 21-51-03-000-801
Installation of the Differential Pressure Sensor AMM 21-51-03-400-801
Removal of the Bleed Pressure Transducer AMM 36-11-03-000-801
Installation of the Bleed Pressure Transducer AMM 36-11-03-400-801
Safety Precautions - Maintenance Practices - ALL SPM 20-00-01-02-01
Wire Repair - Maintenance Practices – ALL SPM 20-12-10-02-01
Electrical Connectors - Description and Operation - ALL SPM 20-20-00-00-01

Troubleshooting Recommendations:

If one of the following faults is recorded in the MDC Fault History or Current Faults follow the troubleshooting below:

ATA21-61 TEMPERATURE CONTROL
FLOW CTRL VLV1 MPE03 DATE
FAILED/WIRING 000xx HH:MM
DISAGREE/VALVE CLOSED
INTERMITNT: 1 FN-------- AIR
Equation ID: B3-006700

ATA21-61 TEMPERATURE CONTROL
FLOW CTRL VLV2 MPE04 DATE
FAILED/WIRING 000xx HH:MM
DISAGREE/VALVE CLOSED
INTERMITNT: 1 FN-------- AIR
Equation ID: B3-006705

  1. Aircraft configuration:
    No APU and/or Engine(s) running.
  2. Navigate to the MDC LRU Test Page and if Equation ID B3-006700, is posted:

    1. Select IASC 1A in the LRU Test Page
    2. Select PRESSURE SENSORS STATUS in the AIR CONDITIONING RAW DATA
    3. Read
    4. BLEED PRESSURE SENSOR1: 00 PSIG
    5. DIFF. PRESSURE SENSOR1: 0.0 PSID

    Or,

  3. If Equation ID B3-006705, is posted:

    1. Select IASC 2A in the LRU Test Page
    2. Select PRESSURE SENSORS STATUS in the AIR CONDITIONING RAW DATA
    3. Read
    4. BLEED PRESSURE SENSOR2: 00 PSIG
    5. DIFF. PRESSURE SENSOR2: 0.0 PSID

  4. If the BLEED PRESSURE SENSOR (MT21 - MT22) does not show 00 PSIG then interchange with the other side and test it again with the other IASC.
  5. If its value is equal with the previous IASC or not equal to 0, then replace it. If not, the input of the first tested IASC may have drifted.
  6. If the DIFF. PRESSURE SENSOR (MT23 - MT24) does not read 0.0 PSID then interchange with the other side and test it again with the other IASC. If its value is equal with the previous IASC or not equal to 0, then replace it. If not, the input of the first tested IASC may have drifted.
  7. If step 2 is good, then inspect the lines of the DPS (MT23 - MT24) and the BPS (MT21 - MT22) for good connection, make sure the fittings and the Bolts are torqued with the correct values.
    NOTE: A 'Flow Control Valve Failed' will generate the same Equation ID in the MDC and the associated EICAS message L(R) BLEED FAULT.
  8. Do the close out.

mt24

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