Instruction Manual

Instructions for Continued Airworthiness 190-01190-11 Rev. 1
for G500H in Robinson R44 Series Rotorcraft Page 17 of 20
Table 2-3. GRS 77H Calibration Criteria
Condition
Calibrations Required
GRS 77H
Pitch/Roll
Offset
See Section 5
of the G500H STC
Installation Manual
GRS/GMU
Magnetic
Calibration
See Section 5
of the G500H STC
Installation Manual
GRS 77H AHRS was removed and/or
replaced. The mounting tray was NOT
removed and the mounting tray bolts
were NOT loosened.
None Required.
GRS 77H AHRS was removed and/or
replaced. The mounting tray WAS
removed and/or mounting tray bolts
WERE loosened.
X X
GRS 77H AHRS Configuration Module
was replaced.
X X
2.7.3 GMU 44 Unit
2.7.3.1 Removal
1. Gain access to the GMU 44 magnetometer.
NOTE
Some metal structures of the GMU 44 may become magnetized if closely exposed to
permanent magnets; therefore it is recommended to use non-magnetic screwdrivers
near the GMU 44 to prevent magnetizing any nearby metal structures.
2. Unscrew the three screws that hold the GMU 44 to its mounting rack.
3. Carefully lift the GMU 44 from the rack.
4. Disconnect the wiring harness.
2.7.3.2 Installation
1. Visually inspect the connectors to ensure there are no bent or damaged pins. Repair any
damage.
2. Connect the wiring harness to the GMU 44.
3. Lower the GMU 44 into the rack and secure the plate with the three Phillips screws.
Original GMU 44 is Reinstalled
If the original GMU 44 was reinstalled, then software loading is not required. This does not include
units that were returned for repair as their software and configuration files are deleted during the
repair testing process. Recalibration is required only if the mount for the magnetometer was
changed. If the magnetometer mount was changed, refer to Section 5.6.2 of the G500H STC
Installation Manual for the GRS 77H/GMU 44 Magnetic Calibration.
New, Repaired or Exchange GMU 44 is Installed
If a new, repaired, or exchange GMU 44 unit is installed, then software must be loaded and the GRS
77H/GMU 44 Magnetic Calibration must be performed. Refer to Section 5 of the G500H STC
Installation Manual for instructions on software loading (5.4.2) and Magnetic Calibration (5.6.2).