Abstract: A container for a fuel tank having an access opening is provided with a closure which fits within a channel in the container to cover the access opening. An elongated bolt has a collapsible cylinder located between the bolt head and the top of the closure to hold the closure to the container. The cylinder is located about the shank of the bolt, and is collapsible above a selected threshold pressure. Under normal bolting conditions, the cylinder is rigid to provide sufficient force to maintain the closure against the tank. Should an abnormal pressure develop within the tank, the closure moves axially along the shank of the elongated bolt, crushing the cylinder and providing additional tank volume to absorb the increased fluid pressure. This reduces the likelihood of catastrophic failure of the closure and also reduces pressure stress on the other tank structures.

Abstract: Aircraft composite components having foam cores comprising at least two foam sheets joined with a sheet of honeycomb to form a foam-honeycomb-foam sandwich. The layers of sheet foam are in contact with each other and the honeycomb cells extend a substantially equal depth into and generally perpendicular to the sheet foam layers. The composite component has increased shear strength. The aircraft composite component can be made by aligning a layer of honeycomb between and generally perpendicular to two layers of sheet foam. A compressive force is applied generally perpendicular to at least one layer of sheet foam so that the honeycomb cells penetrate each of the two layers of sheet foam to a substantially equal depth so that the layers of foam contact each other to form a foam-honeycomb-foam sandwich. The foam core is surrounded by resin impregnated fibers and cured.