07/01/21
Message Overview:
Message Name:
RADIO ALTITUDE DISPLAY NOT SHOWN ON PILOT PFD
| Message Code: | 344OBS016 |
| Effectivity: | All |
| System: | Radio Altimeter System |
| System Description: | 34-44-00 |
| Schematic Diagram: | 34-44-00 [ Global Express ] [ G5000 ] [ Global XRS ] |
| Wiring Diagram: | 34-44-01 [ Global Express ] [ G5000 ] [ Global XRS ] |
Message Description:
Radio Altitude Display is missing on Pilot Primary Flight Display (PFD).
NOTE: During normal operation radio altitude value is removed when altitude is higher than 2500 feet.
Possible Causes:
- Integrated Avionics Computer (IAC) 1 (A11)
- Display Unit (DU) 1 (M7)
- Radio Altimeter 1 (A67)
Troubleshooting Tips:
Advisory Wire/Service Bulletin: None
Forum Articles/Infoservice/Newsletter: None
Before proceeding with troubleshooting, remember that while on ground radio altitude displayed values may be affected by the ground surface material or surrounding equipment near the antennas. If the condition is only present on ground, the aircraft may me moved to another location to monitor the effect.
Quick Links:
| Removal of the Integrated Avionics Computers (IAC) | AMM 31-41-01-000-801 [ Global Express ] [ G5000 ] [ Global XRS ] |
| Installation of the Integrated Avionics Computers (IAC) | AMM 31-41-01-400-801 [ Global Express ] [ G5000 ] [ Global XRS ] |
| Removal of the Electronic Flight-Display Units | AMM 31-61-01-000-801 [ Global Express ] [ G5000 ] [ Global XRS ] |
| Installation of the Electronic Flight-Display Units | AMM 31-61-01-400-801 [ Global Express ] [ G5000 ] [ Global XRS ] |
Troubleshooting Recommendations:
If Radio Altitude data is not received by the IAC or the radio altimeter determine that it’s transmitted data in incorrect (invalid)/missing, a RAD Red flag should be posted on the Pilot PFD. In the case that Radio Altitude Display is missing, it is likely related to PFD 1 (DU) or IAC 1 failure, which can be isolated by doing a PFD/SG reversions.
- Perform a PFD 1 Reversion to ALTN.
- If radio altitude is not displayed on selected DU, go to step 4.
- If radio altitude is displayed on selected DU, continue with next step.
- Return PFD 1 Reversion to normal (NORM).
- Replace DU 1.
- If system checks are good, do close out.
- If fault remains, continue with next step.
- Perform a IAC, SG 1 Reversion to ALTN.
- If radio altitude is not displayed on PFD 1, go to step 7.
- If radio altitude is displayed on PFD 1, continue with next step.
- Return IAC, SG 1 Reversion to normal (NORM).
- Replace IAC 1 (SG).
- If system checks are good, do close out.
- If fault remains, continue with next step.
- Check for Radio Altimeter 1 is correctly computes an altitude of 2500 feet or higher, there will be displayed altitude digits.
- If YES, do close out.
- If NO, continue with next step.
- Perform troubleshooting of Radio Altimeter 1 and associated antenna/coax system in accordance with Observed Fault: Incorrect or Erratic Radio Altitude Value on Pilot PFD.
- Do close out.