Methods and means for maintaining electrical isolation of dissimilar metals when cutting or drilling is required

Claim 1

Material for use within an aircraft jet engine inlet and nacelle structure wherein said material is exposed to the sound of jet engines and other noise producing mechanisms in acoustical attenuation applications, said material having a predetermined flow through resistance and adapted to be cut or drilled in defined selected portions and comprising: (a) a perforated facing sheet; (b) a thin sheet of porous material; (c) a bonding medium bonding said porous material to a face of said perforated sheet selected from the class of adhesive systems whose melt viscosity, during the curing process, is sufficiently high so that the adhesive will not flow into the pores of the porous material by capillary attraction so as to maintain the full porosity of the porous material over the perforations of the perforated sheet, thereby isolating said porous material from the adjacent surface of the perforated sheet, the pores of the porous material providing communication between the outer surface of the porous material and the inner face of the perforated sheet; and (d) a coating of a non electrically conductive liquid epoxy resin material applied to the combined layers of facing sheet, sheet of porous material, and bonding medium in the defined selected locations where cutting or drilling of the combined layers is required, said coating permeating the layers of porous material and bonding material to encapsulate such layers and to coat the walls of the perforations in the perforated facing sheet.