Page 10-6 G300 Installation Manual –TroubleshootingRevision A 190-00921-01Figure 10-4 – AHRS Align Message (PFD)10.3.2 Heading/Pitch/Roll TroubleshootingThe GSU 73 may not be able to provide valid heading/pitch/roll data for the following reasons:1. The GSU 73 external memory module in the harness (that stores the installation configurationparameters) is either not present, or not wired properly. If this is the case, then the externalinstallation configuration parameters will not be considered calibrated. If an “AHRS notCalibrated” message is displayed, the AHRS and/or Magnetometer calibration needs to beperformed, or the GSU 73 configuration module is inoperative.2. The external installation configuration parameters are not considered calibrated. Theseparameters are categorized into 2 sets: AHRS installation, and Magnetic installation. If eitherof these is not calibrated, the GSU 73 heading, pitch, and roll may all be flagged as invalidand an “AHRS not Calibrated” message is displayed. Calibrate the unit to the installation.3. There is not sufficient or valid sensor information being provided to the GSU 73 for it tocompute valid attitude information. Table 10-2 summarizes the inputs the GSU needs toprovide Attitude and Heading information.
