The invention relates to a method of sealing, coating or/and aerodynamic smoothing of at least one connecting element that protrudes from a surface or/and for sealing, coating or/and aerodynamic smoothing of a surface at a gap or at an uneven connection site with a sulfur-containing SCOD sealing compound at at least one application site, especially on an aerospace component, with at least one nozzle element and with at least one irradiation unit, which is characterized in that i) a nozzle element contains a mixed sealing compound and is guided or/and mounted over the connecting element protruding from a surface, over the gap or/and over the uneven connection site, ii) the connecting element protruding from the surface, the gap or the uneven connection site is covered fully with sealing compound, the sealing compound forming a sealing compound cover essentially in the form of a sealing compound cap, a coating or/and a mound-shaped or bead-shaped elevation, iii) the nozzle element or at least a portion is raised if required from the surface having the sealing compound cover, and iv) the curing of the sealing compound is initiated with the aid of at least one irradiation unit by energy input and by release of a latent catalyst or is brought about by direct activation of at least one reaction component, such that the mixed sealing compound subsequently cures or/and cures further. The invention also relates to a corresponding apparatus, to the aerospace vehicle treated in this way and to the use of the method and the apparatus.