Garmin GDU 370 Installation Manual page 61

6.5.2 Antenna Installation Instructions
1. Refer to Table 6-6 (and to Figures in Appendix C) for guidance on selecting the appropriate
mounting cutout. Drill or punch the holes to match the mating part (doubler).
2. Install a doubler plate to reinforce the aircraft skin, as required. Refer to Section 6.5.1 for doubler
preparation and Table 6-6 for additional guidance on the doubler installation. Dimple aircraft
skin when the skin thickness is less than 0.051" for installation of flush head rivets. Countersink
aircraft skin when the skin thickness is between 0.051" and 0.063" for installation of flush head
rivets.
3. Place the install gasket on top of aircraft skin using the four screw holes to align the gasket.
4. Locking nuts are required to secure the antenna (locking nuts installed on doubler). Torque the
four supplied #10-32 stainless steel screws (Garmin P/N: 211-60212-20, MS51958-67, or
equivalent) 20-25 in-lbs. Torque should be applied evenly across all mounting studs to avoid
deformation of the mounting area.
5. Ensure that the antenna base and aircraft skin are in continuous contact with the gasket.
6. Seal the antenna and gasket to the fuselage using Dow Corning 738 Electrical Sealant or
equivalent. Run a bead of the sealant along the edge of the antenna where it meets the exterior
aircraft skin. Use caution to ensure that the antenna connectors are not contaminated with
sealant.
Do not use construction grade RTV sealant or sealants containing acetic acid. These
sealants may damage the electrical connections to the antenna. Use of these type sealants
may void the antenna warranty.
G3X Installation Manual – Antennas
190-01115-01
CAUTION
Page 6-15
Revision A