Garmin GFC 600H Maintenance Manual page 113

Removal
1. Remove power from the GFC 600H FCS and GSU 75H by pulling the FCS and ADAHRS circuit
breakers.
2. Gain access to the GMU 44( ).
3. Disconnect GMU 44( ) circular connector (J441/J442).
4. Remove the three brass screws attaching the GMU 44( ) to install rack and remove the unit.
Re-installation
CAUTION
GMU 44( ) mounting screws must be brass.
NOTE
The metal components in the connector of the GMU 44( ) may slightly affect the magnetic
field sensed by the GMU 44( ). Ensure that the connector remains at least 2 inches from
the body of the GMU after installation to minimize this effect. After attaching the
connector of the GMU to the rotorcraft wiring harness, secure the connector in place
using good installation practices. This will ensure that any remaining magnetic effect can
be compensated for during calibration of the GMU 44( ).
NOTE
The GMU 44 is fastened with brass screws that include a nylon locking patch (Garmin
P/N 211-60037-08). When reusing the original screws, they must be installed with MIL-S-
46163 Type II, Grade N medium strength thread-locker (e.g., Loctite 242(blue) thread
locker); otherwise new screws must be used.
NOTE
The GMU 44( ) must be mounted such that the pitch and roll offsets relative to the
GSU 75H mounting is less than 6.0 degrees.
1. Inspect the GMU 44( ) bracket and install rack, and verify they are securely fastened to the
airframe.
2. Inspect the GMU 44( ) connectors and pins. Repair damage as required.
3. Replace the GMU 44( ) in the install rack such that the arrow on top of the unit is pointing forward
and aligns with the arrow on the unit install rack.
4. Install the three brass screws and connect the unit connector (J441/J442) to the rotorcraft wiring
harness.
Calibrate and checkout the GMU 44( ) following procedures detailed in Section 7.6.
190-02081-03
Rev. 3
GFC 600H HFCS Part 27 STC Maintenance Manual
Page 6-28