Lightning protective seal cap

Abstract

A lightning protective seal cap comprising a seal cap that defines an interior, and a quantity of an uncured sealant that is curable by the application of actinic radiation so as to bind the seal cap to a fastener. The interior of the seal cap contains the quantity of uncured sealant, the seal cap is positionable over the fastener such that at least a portion of the fastener resides in the interior of the seal cap, and when the seal cap is in position over the fastener, the sealant containing seal cap prevents electrical arcing to the fastener from a lightning strike.

We claim: 
     
         1 . A method of protecting a fastener comprising the steps of:
 (i) providing a fastener;   (ii) providing a seal cap which defines an interior;   (iii) applying an uncured sealant to the interior of the seal cap or to the fastener or to both;   (iv) curing the sealant by the application of actinic radiation to the sealant; and   (v) positioning the seal cap over the fastener such that at least a portion of the fastener resides in the interior of the seal cap,   wherein the positioned seal cap contains cured sealant such that electrical arcing to the fastener from a lightning strike is prevented,   wherein the uncured sealant is translucent or transparent to the extent that the average light transmission through one millimeter of the uncured sealant in the 360-750 nm wavelength range is at least 20%.   
     
     
         2 . The method according to  claim 1  wherein the fastener protrudes from a first surface 1 of a substrate article, and every portion of the fastener which protrudes from the first surface of the substrate article is covered by cured sealant or the seal cap or both. 
     
     
         3 . The method according to  claim 1  wherein the method additionally comprises the step of warming the seal cap and uncured sealant to a temperature of at least 20° C., before the sealant is cured. 
     
     
         4 . The method according to  claim 3  wherein the fastener protrudes from a first surface of a substrate article, and when the seal cap is positioned over the fastener, every portion of the fastener which protrudes from the first surface of the substrate article is covered by the cured sealant or the seal cap or both. 
     
     
         5 . The protected fastener construction according to  claim 4 , wherein said first surface is an interior surface of a fuel container. 
     
     
         6 . The method according to  claim 1  wherein the seal cap is translucent or visibly transparent. 
     
     
         7 . The method according to  claim 1  wherein the seal cap, the sealant or both comprises a mixture of a polymer and a nanoparticulate curative. 
     
     
         8 . The method according to  claim 1  wherein application of actinic radiation causes the sealant to be substantially fully cured in less than 60 seconds. 
     
     
         9 . The method according to  claim 1  wherein the uncured sealant is curable by application of blue, violet or UV light. 
     
     
         10 . The method according to  claim 1 , wherein step (iii) is performed before step (v). 
     
     
         11 . The method according to  claim 1 , wherein step (v) is performed before step (iii). 
     
     
         12 . The method according to  claim 1 , wherein said step of curing the sealant comprises application of blue, violet or UV light to the sealant through the seal cap. 
     
     
         13 . The method according to  claim 1 , additionally comprising the step of removing the seal cap mold. 
     
     
         14 . The protected fastener construction according to  claim 4 , wherein said first surface is an interior surface of a fuel container of an aircraft. 
     
     
         15 . The method according to  claim 1 , wherein the fastener protrudes from a first surface of a substrate article and wherein, following steps (iii), (iv) and (v), every portion of the fastener which protrudes from the first surface of the substrate article is covered by sealant.