Abstract: A breather sheet for use in the curing of a composite part comprising two outer layers interposed with a mesh, each outer layer provided with an arrangement of holes and fixed in position to provide a plurality of passageways for air and/or volatiles to pass without restriction, the passageways being such that interposition of the mesh in the assembly of the breather sheet does not substantially obstruct any of the passageways however the mesh is positioned or orientated relative to the outer layers.

Abstract: The invention relates to a method of assembling structures and a component for use in such assemblies. The component is an electrically insulant, compressible impermeable cloth. It is formed by impregnating an electrically insulant woven fibre with a sealant, and curing to form the cloth. Structures, such as airframe structures, may be assembled by positioning the cloth between a substructure and an outer skin on at least part of a sub-structure, and then assembling the outer skin to the sub-structure with the cloth located between the substructure and the outer skin. This provides a greater impermeability and insulation across the structural joint. During assemble the cloth may also be compressed, allowing skin panels to be fixed to the substructure within close tolerances, and allowing steps between adjacent panels to be substantially reduced.