Vibration Mounts; Aluminum Surface Preparation - Garmin GI 275 Installation Manual

4.2.1

Vibration Mounts

For instrument panels with vibration mounts, verify the mounts are grounded to the metallic airframe
structure with a bonding jumper. Ensure the jumper meets the following specifications:
• The cross-sectional area of the strap is greater than 0.016 square inches (approximately
20,800 circular mils)
• The braid is a 7/16" or wider tubular braid (P/N QQB575R30T437, 24,120 circular mils) or a 3/4"
or wider flat braid (P/N QQB575F36T781, 20,800 circular mils)
• The braid contains a terminal lug (mil-spec MS20659-130) at each end
• The strap length is as short as possible, not exceeding 6 inches
Ensure each terminal lug is secured to its respective mating surface with a #10 steel bolt and one flat
washer (P/N AN970-3). Lugs and washers should be center-aligned and flush on all outside edges. These
components should be in full contact with the mating surface.
4.2.2

Aluminum Surface Preparation

In order to prepare the aluminum surface for proper bonding, the following general steps should be
followed. For a detailed procedure, refer to SAE ARP1870 Sections 5.1 and 5.5.
1. Clean grounding location with solvent.
2. Remove non-conductive films or coatings from the grounding location. When area is cleaned
around fastener heads or washers, the area cleaned should be 0.125 inches wider than the footprint
of the washer or the bolt head.
3. Apply a chemical conversion coat, such as Alodine 1200, to the bare metal.
4. Once the chemical conversion coat is dry, clean the area.
5. Install bonding aluminum tape or equipment at grounding location.
6. After the bond is complete, if any films or coatings were removed from the surface, re-apply a
suitable film or coating to the surrounding area.
190-02246-14
Rev. 11
GI 275 STC EIS & MFD Installation Manual
Page 4-6