The pylon, intended to support a flying vehicle engine, includes a primary structure formed by at least one longeron and one panel, the panel including at least one end part provided with a notch, the longeron being provided with an end adapted to be positioned in the notch, the panel and the longeron being assembled by welding a part of the end to a part of the notch. A welded primary structure enables minimization of the blanks of parts associated with the longerons and with the panels by avoiding having recourse to the production of edges.