A heat exchanger including at least a first manifold and a second manifold connected by a bundle of horizontal tubes. An air flow circulates to be cooled by a cooling air flow. The bundle includes at least: a first portion including a first series of tubes with turbulators of passage section corresponding to the section; a second portion including a first series of tubes with no turbulators of passage section and a second series of tubes with turbulators of passage section corresponding to the section; and a distribution box of internal air flow to be cooled including a connection mechanism between the first portion and the second portion.