Abstract: A fluid tight closure for an aperture, more particularly adapted to form a fuel tank access door for an aircraft, preferably made of composite material and providing fail-safe features and resistance to lightning strikes; and further characterized by its light weight, relatively low cost of manufacture, and flexibility to bend from a flat to a curved configuration defined by the curvature of a wing. This fluid tight closure comprises an inner door panel and an outer door panel having each a rim portion complementarily shaped relative to each other and to the edge portion of an aperture, and clamping against the opposite sides of the edge portion with an interposed sealing ring and with nuts and screws sealingly extending through the rim portion and holding the same in clamping position.