Abstract: The lifting surface consists of a torsion box capable of bearing aerodynamic and inertial loads, and the semi-parts (1, 1?) comprising it are connected together with joining means conventionally consisting of a rib in one piece in its plane of symmetry, the final assembly of said lifting surfaces requiring some inspection openings or holes for being able to gain access to the corresponding joints. The invention provides other joining means which avoid that rib and which consist of a plurality of bars (2) modularly arranged in the manner of a lattice, in such a is way that the required amount of said inspection holes is reduced, and a sequential assembly connecting the upper and lower ends of the bars (2) is facilitated.