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2.3
Wiring
Use AWG #24 or larger wire for all connections unless otherwise specified by the aircraft manufacturer
or Garmin. The standard pin contacts supplied in the connector kit are compatible with up to AWG #22
wire. In cases where some installations have more than one unit sharing a common circuit breaker, sizing
and wire gauge is based on aircraft circuit breaker layout, length of wiring, current draw of units, and
internal unit protection characteristics. Do not attempt to combine more than one unit on the same circuit
breaker unless it is specified on aircraft manufacturer approved drawings.
In some cases, a larger gauge wire such as AWG #18 or #20 may be needed for power connections. The
provided connector kit supplies extended barrel contacts for AWG #18 and #20 wire, if required. Special
thin-wall heat shrink tubing is also provided to insulate the extended barrels inside the backshell. If using
extended barrel contacts, ensure that no two extended barrel 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, RF or 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.
2.4
Cooling Air
No cooling air is needed for either the GRS 77 or the GMU 44. Refer to the G1000 System Installation
Manual, Garmin part number 190-00303-00, for information on G1000 system cooling requirements.
2.5
Aircraft Mounting Requirements for GRS 77/GMU 44
The following guidelines describe proper mechanical installation of the Garmin GRS 77 AHRS and
GMU 44 Magnetometer. The guidelines include requirements for proper location selection in the aircraft,
requirements for supporting structure and mechanical alignment and restriction on nearby equipment.
The post-installation calibration procedures required prior to flight are described in Section 5.
The GRS 77H 011-00868-20 and the GMU 44 011-00870-10 units are required for
helicopter installations.
Page 2-4
Revision L
NOTE
GRS 77/GMU 44 Installation Manual
190-00303-10
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