An aircraft wing assembly comprising: a spar; a fuel tank; a track container which is attached to the spar and extends into the fuel tank; a track which extends through the spar and into the track container; and a high-lift device, such as a slat or flap, carried by the track. The track container comprises a stiffening element encased in an elastomeric sheath. The track container is manufactured by placing a stiffening element and elastomeric material together in a mould; and compressing and heating them to cure and shape the elastomeric material.