Figure 3-5 Bonding Strap; Table 3-14 Airframe Bonding Hardware; Transponder Antenna Bonding - Garmin GTX 335 w GPS Installation Guidance

Item Number
Refer to Figure 3-5
1
2
3
4
5
6
7

3.15.3 Transponder Antenna Bonding

CAUTION
If the antenna is struck by lightning, the foil by itself may not be sufficient to dissipate
lightning currents. Additional protection may be needed depending on the construction of
the structure to which the antenna is attached. Refer to aircraft SRM for more information.
NOTE
For nonmetallic aircraft, the ground plane can be composed of heavy duty aluminum foil
tape, such as 3M P/N 438, 3M P/N 436, or other adhesive backed dead soft foil with
aluminum 7.2 mils or greater.
Follow these precautions when planning installation of the antenna:
1. The ground plane should be 12 inches minimum radius around the perimeter of the antenna. Refer
to figure 3-6. For metallic aircraft, the surrounding metal skin that the antenna is attached supplies
the ground plane.
2. The antenna baseplate must be electrically bonded to the ground plane.
3. The electrical bond must achieve direct current (DC) resistance less than or equal to 2.5 mΩ.
4. The paint on the outer skin of the aircraft, under the footprint of the antenna baseplate should not
be removed unless it is necessary to meet bonding requirements.
190-00734-17
Rev. 1

Table 3-14 Airframe Bonding Hardware

Tinned copper flat braid, 3/4", QQB575F36T781, or
Tinned copper tubular braid, 7/16", QQB575R30T437
Terminal lug, 5/16-inch, uninsulated, MS20659-131
Bolt, 5/16-inch, AN5-XA
Lock washer, 5/16-inch, NASM35338-45
Flat washer, 5/16-inch, NAS1149F0563P
Flat washer, 0.063-inch thick, NASM970-5 (AN970-5)
Locknut, 5/16-inch, AN363-524
3
4
5
6
6
7

Figure 3-5 Bonding Strap

Description
2
INSTRUMENT PANEL
OR
AIRFRAME GROUND
(REF)
GTX 335 w/GPS Installation Guidance
1
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