Forming a lightning spark isolation barrier

• US 4,382,049 A
• Filed: 11/30/1981
• Issued: 05/03/1983
• Est. Priority Date: 11/30/1981
• Status: Expired due to Term

• Current Assignee: Mcdonnell Douglas Corporation (The Boeing Co.)
• Original Assignee: Mcdonnell Douglas Corporation (The Boeing Co.)
• Inventors: Amason, Myron P., Hofmeister, Michael G.
• Primary Examiner(s): LOWE, JAMES
• Application Number:
  US06/326,142
• Time in Patent Office: 519 Days
• Field of Search: 264/261, 264/262, 264/263, 264/272.16, 264/40.1, 264/268, 264/275, 264/279, 174/30, 174/138 D, 174/2, 244/1 A, 244/132, 361/215, 361/218
• US Class Current: 264/40.1
• CPC Class Codes: B29C 70/74 Moulding material on a relatively small portion of the preformed part, e.g. outsert moulding B29C70/845 takes precedence
• CPC Class Codes: B64D 45/02 Lightning protectors; Static dischargers in general H01T
• CPC Class Codes: F16B 33/004 Sealing; Insulation by means of washers F16B43/001

Abstract

A controlled dielectric barrier is created surrounding a fastener to isolate its sparking areas. The barrier is formed by creating a cap to define a desired cavity between the cap and the fastener and then dielectric isolation material is placed in the cavity and held in place by the cap until hardened. The cap may then be removed from the fastener as desired.

Claims

1. A method of making a lightning spark isolation barrier for surrounding a fastener comprising the steps of:

determining the areas of sparking and Joule heating of the fastener;

evaluating the isolation potential of the dielectric material to be used;

defining a cavity surrounding the fastener to be isolated with the dielectric material;

creating a cap to enclose the cavity surrounding the fastener, and

using the cap to hold a defined amount of dielectric isolation material in viscous plastic form surrounding the critical sparking and Joule heating areas of the fastener until the isolation material has cured to a hardened state.

2. The method of claim 1 wherein the determination of the sparking and Joule heating areas of the fastener are defined by simulated lightning sparking tests.

3. The method of claim 2 wherein the cap is aligned on the fastener by engaging protrusions on the fastener.

4. The method of claim 3 wherein the viscous plastic dielectric isolation material is first placed in the cap and then the cap is forced over the fastener to emplace the dielectric isolation material.

5. The method of claim 3 wherein the cap is first emplaced on the fastener and then the dielectric isolation material in viscous form is injected into the cavity between the cap and the fastener to isolate the critical sparking and Joule heating areas.

6. The method of claims 3 or 4 wherein the cap is removed following the curing of the isolation material to a hardened state.