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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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Quick Links

05/01/25

Message Overview:

Message Name:

DISAGREE / VALVE OPEN
(Service Message)

Message Code:

B3-361622

Associated CAS:

PACK COOL AIR FAIL
(Advisory)

Reporting LRU: RAM AIR REG VLV
System Description: 21-53-00 - Ram-Air System
Schematic Diagram: 21-53-00 - Ram-Air System
Wiring Diagram:

21-52-17 - Compressor Discharge Temperature Sensor
21-61-29 - Hot Air Temperature Sensor

Message Description:

The Integrated Air System Controller 2, IASC2 has detected a failure in the Primary or Backup control circuits for the RARV. The valve has failed in the open position.

Possible Causes:

  • Integrated Air System Controller 2 (IASC2) (A56)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

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

Flight Operation Notifications Manual (FONM): None

NOTES:

  • The valve can be deactivated IAW AMM TASK 21-53-05-040-801, then re-activated IAW AMM TASK 21-53-05-440-801.
  • There are 2 control modes:

  1. Normal Operation (Pack + Trim) and Pack Only

    • IASC2 modulates RARV to obtain: 100°C (212°F) < PIT < 170°C (338°F).
      NOTE: If channel A failed → the control of RARV is performed on IASC2 channel B (redundancy).

  2. Trim Only

    • The IASC2 modulates RARV to obtain: 3°C (37.4°F) < HAT < 70°C (158°F).

    iasc



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 Ram Air Regulating Valve AMM 21-53-05-000-801
Deactivation of the Ram Air Regulating Valve AMM 21-53-05-040-801
Installation of the Ram Air Regulating Valve AMM 21-53-05-400-801
Activation of the Ram Air Regulating Valve AMM 21-53-05-440-801
Standard Practices - Wiring SPM 20-12-00-02
Standard Practices - Wire Repair SPM 20-12-10-02

Troubleshooting Recommendations:

  1. Do the operational test of the temperature control and indication system: AMM Task 21-61-00-710-801.
  2. Does the test pass?

    1. If YES, go step 7.
    2. If NO, continue with the next step.

  3. Do wiring continuity check from MT sensors (MT25), (MT27) and (MT29) to IASC 2 (A56).

    FROM
    MT TEMP SENSOR    		 TO
    IASC 2 (A56)    		 RESULTS
    MT27P1-4 A56P1-48
    MT27P1-6 A56P1-65
    MT25P1-4 A56P3-17
    MT25P1-6 A56P3-18
    MT29P1-4 A56P1-26
    MT29P1-6 A56P1-49

  4. Is the result correct?

    1. If YES, continue with the next step.
    2. If NO, repair wiring as required and do close out.

  5. interchange the defective sensor with another one.
  6. Is the fault follow the sensor?

    1. If YES, replace the defective sensor and do close out.
    2. If NO, continue with the next step.

  7. Visually inspect the position of lever of the RAV, it should be in Full Open position on ground.
  8. Perform the PBIT of the IASC #2 by resetting the circuit breakers D14 (LCPB), D14 (RCBP) and E10 (RCBP).
  9. Wait for 30 seconds the PBIT is finished and make sure the PACK COOL AIR FAIL Advisory EICAS message is not shown.
  10. If the PACK COOL AIR FAIL is shown, check wiring between the IASC #2 and the RAV.
  11. Interchange the IASC #2 with the IASC #1 and do again the PBIT if the wiring check is good.
  12. Do close out.

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