190-01639-00
GSU 75 ADAHRS Installation Manual
Rev. 6
Page 2-3
2.4 Additional Equipment Required
•
Cables - The installer will supply all system cables including circuit breakers. Cable requirements
and fabrication is detailed in Section 3 of this manual.
•
Hardware required to mount the GSU 75 Remote Rack is not provided.
•
Air hoses and fittings to connect pitot and static air to the GSU 75(X). The GSU 75(X) has a
female 1/8-27 ANPT brass fitting for each pitot and static port. Use appropriate aircraft fittings to
connect to pitot and static system lines.
•
#18 or #20 AWG wire contacts, Garmin part number 336-00044-00 (only required if #18 or #20
AWG wire is used)
2.5 Cabling and Wiring
Refer to the interconnect examples in
In some cases, a larger gauge wire such as #18 or #20 AWG may be needed for power connections. If using
#18 barrel contacts, ensure that no two contacts are mounted directly adjacent to each other. This
minimizes the risk of contacts touching and shorting to adjacent pins and to ground.
Ensure that routing of the wiring does not come in contact with sources of heat or RF/EMI interference.
Check that there is ample space for the cabling and mating connectors. Avoid sharp bends in cabling and
routing near aircraft control cables.
2.6 Electrical Bonding
Electrical equipment, supporting brackets, and racks should be electrically bonded to the aircraft’s main
structure. Refer to SAE ARP 1870 Section 5 when surface preparation is required to achieve electrical
bond. An equivalent OEM procedure may also be substituted. The electrical bond should achieve direct
current (DC) resistance less than or equal to 2.5 milliohms to local structure where the equipment is
mounted. Compliance should be verified by inspection using a calibrated milliohm meter.
For aircraft that require protection from lightning waveform 5A at levels higher than DO160F section 22
Level 3 cable bundle testing, the GSU 75/GRS 79 backshell must have a ground strap to airframe directly
in addition to the grounding provided by the chassis. The strap must be minimum of 5/8 inches wide (e.g.
QQB575F-36-T0375 or larger) and no longer than 10 inches. One end of the braid must be terminated to
the Garmin backshell and the other end terminated directly to airframe ground.
340095
The document reference is online, please check the correspondence between the online documentation and the printed version.
