Garmin G3X Installation Manual page 177

4. While a magnetic anomaly is detected and the aircraft is determined to be stationary, the
value of the heading output is frozen. When either the aircraft is determined to be no longer
stationary or the magnetic anomaly ceases, heading will be unfrozen and determined as
useable. In this context, the aircraft is considered to be stationary when its yaw rate is less
than 1.0 degrees/second and all other angular rate and acceleration values are sufficiently
small. (moving or shaking the wings or tail for example can cause a Red-X to be displayed).
5. Check to see if any new equipment has been installed on the aircraft, and reference Table 3-7
for minimum distances for installed equipment from the GMU 44 to prevent interference.
If the GMU 44 heading is not present on the GDU 37X, there may be a problem with the RS-232 or
RS-485 line between the GSU 73 and GMU 44. Troubleshoot any possible wiring/connector issues
before replacing either unit.
10.5.3 Attitude/Heading Failure Troubleshooting
Figure 10-6 – Attitude and Heading Failure Indications
Prior to troubleshooting an Attitude Failure, gather answers to the following questions. This information
may be helpful to the installer/pilot, the G3X Dealer, or to Garmin Aviation Product Support in
troubleshooting the failure.
1. What specifically was the nature of the failure? Was it a Red-X of only heading, only
pitch/roll, or both?
2. If there was a Red-X of pitch or roll information, did the PFD display the "AHRS Align:
Keep Wings Level" message (which is indicative of an AHRS reset), or the "Attitude Fail"
message (which is indicative of either AHRS invalidating its output, or a communication path
failure)?
3. What exactly was the aircraft doing in the two minutes that preceded the failure (taxing on
the ground, flying straight-and-level flight, turning, climbing, etc)? If the problem occurred
on the ground, was it within 100 feet of a hanger using GPS repeaters?
4. How long did the failure last? Was it brief or sustained? Was it repetitive in nature? If it
was repetitive, about how many times did it happen? Did it happen on more than one day?
G3X Installation Manual - Troubleshooting
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(Reversionary or Split-Screen PFD)
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Revision E