Page 12-10
G900X/G950 Installation and Maintenance Manual – Garmin GPS WAAS Antenna
Revision D
190-00719-00
12.5.7 Antenna Grounding
The antenna is grounded through the mounting hardware and the coax connection. The mounting
hardware (washers and nuts) and doubler plate should make contact with an unpainted grounded surface
ensuring proper antenna grounding. It is important to have good conductivity between the coaxial shield
and the ground plane. The bottom of the antenna does not need to make contact with the ground plane
(i.e. the surface may be painted). The antenna will capacitive couple to the ground plane beneath the
paint or aircraft cover.
12.5.8 Teardrop Footprint Antenna Installation (GA 35)
This section describes the structural mounting of the teardrop footprint antenna installation. One
acceptable method is to use Garmin P/N: 115-00846-10 doubler plate. Another acceptable method is to
fabricate and install one of three doublers, Figure 12-5, Figure 12-6, and Figure 12-7, depending on the
thickness of the skin. The three doubler designs vary only by number of rivets and hole preparation for
installation with flush rivets. Figure 12-15 shows installation of the stud mount teardrop footprint
antenna.
Table 12-5 provides a summary of design and installation details for the antenna doubler. Figure 12-8
shows an example of the doubler installed between stringers on the top fuselage skin, just off centerline.
The location should be flat, with no gaps between the skin and doubler, to keep from deforming the skin
during installation.
Table 12-5. Teardrop Footprint Antenna Doubler Design and Installation
Skin Thickness
0.032” to 0.049”
0.049” to 0.051”
0.051” to 0.063”
Doubler Design (Figure)
Figure 12-5
Figure 12-6
Figure 12-7
Number of Rivets Required
12
16
16
Type of Rivets Required
1
MS20426AD4-x
MS20426AD4-x
MS20426AD4-x
Skin Preparation for Rivets
Dimple
Dimple
Countersink
Doubler Preparation for Rivets
Countersink
Countersink
None
Skin Cutout Detail (Figure)
Figure 12-9
Figure 12-10 Figure
12-11
Doubler Installation (Figure)
Figure 12-12
Figure 12-13
Figure 12-14
Notes:
1. Rivet length determined at installation, dependent on thickness of material (rivet length = grip
1.5*rivet diameter)
