Post Installation Calibration Procedures - Garmin G3X Installation Manual

5. Was the problem correlated with a specific maneuver or a specific geographic area?
6. Can the problem be repeated reliably?
7. Were any of the following message advisory alerts observed (must navigate to the INFO page
and press the MSG softkey to see them) within an hour of the occurrence of the problem?
•
AHRS not receiving airspeed
•
AHRS not receiving any GPS information
•
AHRS magnetic-field model out of date
•
AHRS extended operation in no-GPS mode
8. Did the onset of the problem occur shortly after a software upload to one or more of the G3X
LRU's, or shortly after a repeat of the magnetometer calibration procedure?
9. Were there any GPS Alert messages or loss of position lock?
The GSU 73 may not be able to provide valid heading/pitch/roll data for the following reasons:
1. If an "AHRS not Calibrated" message is displayed, the GSU 73 external memory module in
the harness (that stores the installation configuration parameters) is either not present or not
wired properly. In this case, either:
•
The GSU 73 configuration module is inoperative. OR
•
The external installation configuration parameters are not calibrated and the AHRS
and/or Magnetometer calibration needs to be performed. If either of these is not
calibrated, the GSU 73 heading, pitch, and roll may all be flagged as invalid. Calibrate
the unit to the installation.
2. There is not sufficient or valid sensor information being provided to the GSU 73 for it to
compute valid attitude information. Table 10-1 summarizes the inputs the GSU needs to
provide Attitude and Heading information.

10.6 Post Installation Calibration Procedures

The calibration procedures in Sections 9.3.3 and 9.3.5 may be performed during troubleshooting.
Tables 9-2 and 9-3 list the status box requirements for each calibration procedure. The
Magnetometer Interference Test may be used to determine if the location of the GMU 44 is
susceptible to magnetic interference. The Engine Run-Up Vibration Test can be used to
determine if the mounting of the GSU 73 and GMU 44 are susceptible to aircraft vibration.
Passing the Engine Run-Up Vibration test does not remove the requirement to rigidly
mount the GSU 73 to the aircraft primary structure. The Engine Run-Up Vibration Test
is intended to help discover mounting issues but successful completion of the test does
not validate the mounting of the GSU and GMU, and does not account for all possible
vibration profiles that may be encountered during normal aircraft operation
Page 10-8
Revision E
NOTE
G3X Installation Manual –Troubleshooting
190-01115-01