Garmin G900X Installation And Maintenance Manual page 280

15.4.3 GRS77/GMU 44
The GRS 77 AHRS unit and the GMU 44 magnetometer unit require calibration before first flight. There
are four procedures to be carried out (Sections 15.4.3.1, 15.4.3.3, 15.4.3.4, 15.4.3.5, 15.4.3.6 ). The
aircraft engine must be started after the first procedure is complete. When ready to perform the
procedures, shut the PFD(s) and MFD off by pulling the PFD(s) and MFD circuit breakers. Restart both
displays in configuration mode.
15.4.3.1 Procedure A: GRS 77 Pitch/Roll Offset Calibration
This procedure must be carried out with the engine off. Go to the GRS page group on PFD #1. Select the
GRS/GMU Calibration page on PFD #1.
To perform the following procedures press the following softkeys:
a) 9
b) 10
c) 11
d) 12 (Far Right softkey)
1. Level the aircraft to within ±0.25° of zero pitch and zero roll.
Page 15-38 G900X/G950 Installation and Maintenance Manual – Software, Configuration, and Calibration
Revision D
Figure 15-28. GRS/GMU Calibration Page
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