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Select color for CAS message that you wish to troubleshoot

(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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04/26/21

Message Overview:

Message Name:

IRS 1/IRS 2 FLAG (Caution)

Identifier: 342OBS001
Effectivity: AIRCRAFT 20501 - 20999
System: Navigation
System Description: 34-45-00
Schematic Diagram: None
Wiring Diagram: 34-45-01

Message Description:

The amber 'IRS 1/IRS 2' caution flag indicates that the IRS reversion has been selected and the indicated IRS is providing data to both PFDs.

  • The reversionary switching has selected one source for the IRS, there is no system redundancy

Possible Causes:

  • Input/Output Concentrator (IOC) (A4-IOC)
  • Inertial Reference Unit 1 (IRS 1) (A233)
  • Inertial Reference Unit 2 (IRS 2) (A232)
  • Data Bus Failure
  • IRS source select switch on the Reversion Select Panel (PL27)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

Quick Links:

Removal of the Input/Output Concentrator Unit (IOC) AMM 31-45-05-000-801
Installation of the Input/Output Concentrator Unit (IOC) AMM 31-45-05-400-801
Operational Test of the Input/Output Concentrator Unit (IOC) AMM 31-45-05-710-801
Operational Test of the Inertial Reference System (IRS) AMM 34-45-00-710-801
Removal of the Inertial Reference Unit (IRU) AMM 34-45-01-000-801
Installation of the Inertial Reference Unit (IRU) AMM 34-45-01-400-801
Wiring - Maintenance Practices - ALL SPM 20-12-00-02
Wire Repair - Maintenance Practices - ALL SPM 20-12-10-02

Troubleshooting Recommendations:

  1. Set the IRS source reversion selection knob (PL27) to the NORM position. Is the indication still present?

    1. If YES, continue with next step.
    2. If NO, do close out.

  2. Perform a wiring check between the IRS source reversion selection knob (PL27) and the PFDs and MFDs.

    1. If wiring defects are found, repair defective wiring as required and do close out.
    2. If no defects are found, continue with next step.

  3. Perform a continuity check directly on IRS source select switch on the Reversion Select Panel. Repair/replace if required.
  4. Do close out.

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