Preparation Of Aluminum Surfaces; Composite Aircraft - Garmin GTX 330D Maintenance Manual

B.2 Preparation of Aluminum Surfaces
The following general procedure is recommended to prepare an aluminum surface for proper electrical
bonding.
1. Clean grounding location with solvent.
2. Remove non-conductive films or coatings from the grounding location.
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 equipment at grounding location.
6. After the bond is complete, reapply a suitable film or coating to the surrounding area, if any films
or coatings were removed from the surface.
For a more detailed procedure, refer to SAE ARP1870 Sections 5.1 and 5.5.
B.3 Composite Aircraft
Use the following guidance when repairing or replacing special bonding components. Use aluminum tape
(3M P/N 436, 438, or other adhesive-backed dead soft aluminum foil with minimum 7.2 mils metal
thickness) when replacing existing aluminum foil that has been damaged. A tape maximum length-to-
width ratio of 7:1 must be maintained (i.e., up to seven inches in length for every one inch in width).
Maintain the existing aluminum tape routing, while maintaining the same width as the tape being replaced.
Additional guidance can be found in AC 43.13-1B and SAE ARP1870, sections 5.1 and 5.5.
Additional considerations:
• Isolate tape from carbon composite material
• Verify tape does not have any tears in the joint or along the length of the tape
• Fold tape over twice to itself when bonding to metal part
• Cover folded tape area with thin aluminum plate
• Clean metal-to-metal contact points
• Secure plate and tape to metal part with multiple fasteners
190-00734-11
Rev. 6
GTX 33X and GTX 3X5 ADS-B Maintenance Manual
Page B-4