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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

08/14/25

Message Overview:

Message Name:

NO OUTPUT

Message Code:

B3-648322

Associated CAS:

None

Reporting LRU: RAD ALT 4000
System Description: 34-44-00 - Radio Altimeter System 
Schematic Diagram: 34-44-00 - Radio Altimeter System 
Wiring Diagram: 34-44-01 - Radio Altimeter Antenna

Message Description:

No RAD ALT data received at (L-IOC, R-IOC).

Possible Causes:

  • Radio Altimeter Transceiver (RAD ALT-4000) (A32)
  • KA Band Viasat Modem
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

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

Flight Operation Notifications Manual (FONM): None

NOTES:

  • If the aircraft is equipped with a KA Band Viasat modem system, modem failure may result in failure of the RAT ALT.

Quick Links:

Standard Aircraft Configuration for Maintenance AMM 12-00-00-867-803
Electrical/Electronic Safety Precautions AMM 24-00-00-910-801
Electrostatic-Discharge Safety Precautions AMM 24-00-00-910-802
Connect Electrical Power to the Aircraft AMM 24-00-00-861-801
Remove the Electrical Power from the Aircraft AMM 24-00-00-861-802
Removal of the Radio Altimeter Transceiver AMM 34-44-01-000-801
Installation of the Radio Altimeter Transceiver AMM 34-44-01-400-801

Troubleshooting Recommendations:

  1. Reset RAD ALT (CB1-A7) circuit breaker.

    1. If system checks are good, do close out.
    2. If fault remains, continue with next step.

  2. Confirm the presence of the 28 VDC and the grounds at Radio Altimeter Receiver connector A32P1. Repair/replace as required.

    1. If system are good, do close out.
    2. If fault remains, continue with next step.

  3. Verify the antenna and make sure no corrosion or water ingress is found between the antenna and the skin. Also is recommended to verify the Electrical bonding resistance of the Radio Altimeter Antenna as per SPM 51-80-00-760-802.

    1. If system checks are good, do close out.
    2. If fault remains, continue with next step.

  4. Replace Radio Altimeter Receiver or Antenna.
  5. Do close out.

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