An aircraft structural element having a cavity. The structural element has an opening in a wall of the cavity through which moisture located in the cavity can escape into the surroundings, wherein a drainage element for sealing the opening in the wall of the cavity is provided in the opening. In order that the structural element can be produced with a low expenditure on components and assembly equipment, the drainage element comprises a hollow cylinder which connects the cavity of the structural element to the surroundings, which is provided with an external thread having a predefined external diameter, and a head at one end which has a predefined diameter, wherein the external diameter of the thread is smaller than the head diameter.