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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

04/26/21

Message Overview:

Message Name:

RADIO ALTIMETER FLAG (Caution)

Identifier: 345OBS002
Effectivity: AIRCRAFT 20501 - 20999
System: Navigation
Associated CAS: None
System Description: 34-14-00
Schematic Diagram: None
Wiring Diagram: 34-44-01

Message Description:

The amber 'RA' caution flag identifies that the on-side Radio Altimeter is inaccurate or a miscompare between the PFDs exist.

  • The system uses a single R/T for radio altimeter indications, left and right indications are sent on left and right data bus to the respective IOC.
  • Cross comparator or splits, could be associated with a bad IOC, Radio Altimeter R/T or Data bus failure.
  • MDC troubleshooting information may help isolate data validity, prior to component replacement and data bus-ring out.

45_current_faults

Possible Causes:

  • Radio Altimeter Receiver/Transmitter (RAD ALT) (A32)
  • Input/Output Concentrator (IOC) (A4-IOC)
  • Data Concentrator Unit (DCU) (A14)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

NOTE: A metallic or reflective surface (Water, Ice, metal plates, metal grills, etc...) underneath the RA antennas when aircraft is on the ground can cause erratic readings and cause the unit to fail. The first thing that should be attempted is move the A/C a few feet and test the system again.

Quick Links:

Removal of the Data Concentrator Unit (DCU) AMM 31-41-01-000-802
Installation of the Data Concentrator Unit (DCU) AMM 31-41-01-400-802
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 Radio Altimeter System AMM 34-44-00-710-801
Removal of the Radio Altimeter Transceiver AMM 34-44-01-000-801
Installation of the Radio Altimeter Transceiver AMM 34-44-01-400-801
Removal of the Radio Altimeter Antenna AMM 34-44-09-000-801
Installation of the Radio Altimeter Antenna AMM 34-44-09-400-801
Wiring - Maintenance Practices - ALL SPM 20-12-00-02
Wire Repair - Maintenance Practices - ALL SPM 20-12-10-02
Electrical Connectors - Maintenance Practice - ALL SPM 20-20-00-02

Troubleshooting Recommendations:

  1. Troubleshooting using the MDC current fault page may help isolate the system, verify that power is available and check the data bus information.
  2. Interrogate the MDC as follows:

    1. 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.
    2. 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 fault. Going into advanced diagnostics will provide an equation id for the fault identified
    3. Select the MDC fault or equation from the drop down below to provide additional information to assist in troubleshooting.
    4. If no MDC Fault Codes/Messages are present continue with next step for troubleshooting.
    5. Swap IOC.

      1. If squawk remains return IOCs to original positions.
      2. Continue with next step.

    6. Replaced Radio Altimeter (RA). Does amber box 'RA' flag clear?

      1. If YES, do close out.
      2. If NO, check associated wiring.

    7. Do close out.

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