An assembly method for an air intake of a jet engine of an aircraft, comprising providing an acoustic panel, an outside panel, flanges and a collar, arranging a rear edge of the acoustic panel on an assembly chassis. The flanges and the collar are attached at the rear edge of the acoustic panel. A rear edge of the outside panel is attached to the attached collar. A first set of geometric data of a front edge of the acoustic panel is measured and a second set of geometric data of a front edge of the outside panel is measured. A U-shaped lip as a single element is produced based on the two sets of geometric data. An inside leg of the lip is attached to the front edge of the acoustic panel and an outside leg of the lip is attached to the front edge of the outside panel.