Garmin GI 275 Installation Manual page 152

GMU 44B installations in a non-conductive (i.e., composite) airframe must maintain a minimum of
0.5 inches of clearance from any conductive structure or component. If the conductive structure in
composite airplanes is the only option for the GMU 44 installation, it must be electrically isolated. This
can be accomplished using the clickbond fixtures.
Refer to the aircraft model-specific maintenance manual, structural repair manual, or standard practices
manual for the selection of materials and processing.
The GMU 44B can be mounted using composite base aluminum threaded studs bonded to the aircraft
structure. CB4000 or CB4017 bonded composite base studs manufactured by Click Bond, Inc. (2151
Lockheed Way, Carson City, NV 89706-0713) are examples of parts that can be used to install the GMU 44
bracket in airplanes with composite airframes. Bond gap must be 0.020 inches minimum.
NOTE
Ensure enough epoxy material is used to assure a minimum puck thickness of 0.02 inches.
In some installations, it is desirable to mount the GMU 44B Magnetometer in the wingtip of a metal
aircraft that has non-metallic (e.g., fiberglass) wingtip covers. If this is the case, the following
requirements must be met:
• The aircraft must have wingtip navigation lights installed
• Heavy overbraid must be installed over the wiring from the GMU 44B to where the wiring exits
the wingtip
• The overbraid must be terminated at this wingtip exit point using a #10 terminal lug and stud
• The resistance between the overbraid and that structure must be 2.5 mΩ or less
• The GMU 44B must be mounted to a metal rib that does not enclose a fuel bay
• There must be at least one intermediate rib between the rib that encloses the fuel bay and the rib on
which the GMU 44B is installed
• The GMU 44B mounting bracket must be electrically bonded to the wing using fasteners or rivets
190-02246-10
Rev. 11
GI 275 Part 23 AML STC Installation Manual
Page 4-51