A seal assembly for closing an aperture in an aerodynamic surface of a structure, the seal assembly comprising: a track for attachment to the structure; and a retractable seal including a flexible substrate and a plurality of rods connected to the substrate, wherein at least one of the rods is mounted for running movement along the track, and the seal is moveable between an extended position and a retracted position by moving the at least one rod along the track accompanied by folding/unfolding of the seal substrate, and wherein the seal is biased to its extended position.