Pressurized Aircraft Considerations; Shield Termination Considerations - Garmin GTX 335 w GPS Installation Guidance

3.14.1 Pressurized Aircraft Considerations

Wiring that penetrates the pressure vessel must be installed in accordance with the Type Design Data for the
aircraft. Use existing provisions for any wires that penetrate the pressure bulkhead (e.g., existing bulkhead
connectors or existing sealed wire through-holes). Additional holes in the pressure vessel are beyond the
scope of the GTX 33/330 and GTX 3X5 Part 23 AML STC and require more data from the aircraft
manufacturer or other FAA approved data.

3.14.2 Shield Termination Considerations

Shield termination at non-Garmin equipment end must be as short as possible and must not exceed three
inches in length unless the manufacturer's installation requirements specify differently. When there are no
requirements given by the manufacturer's installation manual, the shields can be connected to the metal
connector backshell when the backshell is grounded to airframe chassis ground. Alternatively, the shield
termination can be directly connected to airframe chassis ground.
All shields must have continuity at any intermediate connectors used unless specified differently. Audio line
shields should be continuous from end-to-end and be grounded at only one end to prevent ground loops.
The interconnect diagrams, and accompanying notes in appendix B, should be closely followed to
minimize interference effects.
If wiring from the GTX goes to a unit that uses overbraided wires then the new wiring at the unit must also
be overbraided. If the wiring passes through bulkhead connectors then each segment must be overbraided
and the overbraid must be grounded at both ends unless instructed differently in the equipment's installation
manual. The overbraid must be terminated as close to the connector as possible and in accordance with
manufacturer's installation requirements
190-00734-17 GTX 335 w/GPS Installation Guidance
Rev. 1 Page 3-14