Assembly for a nacelle of an aircraft, said assembly comprising: - a fixed cowl that is intended to be attached to a rigid structure of the nacelle and has an opening in its web, forming a window, - a movable cowl that is mounted so as to be able to move on the fixed cowl between a closed position in which the movable cowl blocks the window and an open position in which the movable cowl does not block the window, and comprising an upper edge that is intended to be oriented towards the top of the nacelle and a lower edge on the opposite side from the upper edge, the movable cowl having a reinforcing rib between its upper edge and its lower edge, the fixed cowl comprising, in continuation of the reinforcing rib of the movable cowl, an upper reinforcing rib which extends from that edge of the window corresponding to the upper edge and a lower reinforcing rib which extends from that edge of the window corresponding to the lower edge, - at least one hinge (212a-b), where each hinge (212a-b) comprises a fixed part in the form of a female clevis attached to the upper reinforcing rib along the upper edge of the fixed cowl, a movable part in the form of a male fitting attached to the reinforcing rib of the movable cowl, where the movable part is accommodated in the fixed part, and a pin mounted between the fixed part and the movable part and in which each pin is parallel to the upper edge, - at least two locks (220a-b) arranged along the lower edge of the movable cowl, where each lock (220a-b) comprises a first part secured to the lower reinforcing rib, a second part secured to the reinforcing rib of the movable cowl, locking means that are able to move between a locking position which locks the first part and the second part to one another and an unlocking position in which the first part and the second part are free with respect to one another, and actuation means that are provided in order to move the locking means from the locking position to the unlocking position and vice versa, - a fitting to which are attached the fixed parts, - a fitting to which are attached the movable parts, - a fitting to which are attached the first parts and - a fitting to which are attached the second parts, and wherein each fitting (240a-d) is attached on one hand to the corresponding reinforcing rib (230a-b, 232), and on the other hand to the cowl (206, 210) bearing the corresponding reinforcing rib (230a-b, 232). - a fixed cowl that is intended to be attached to a rigid structure of the nacelle and has an opening in its web, forming a window, - a movable cowl that is mounted so as to be able to move on the fixed cowl between a closed position in which the movable cowl blocks the window and an open position in which the movable cowl does not block the window, and comprising an upper edge that is intended to be oriented towards the top of the nacelle and a lower edge on the opposite side from the upper edge, the movable cowl having a reinforcing rib between its upper edge and its lower edge, the fixed cowl comprising, in continuation of the reinforcing rib of the movable cowl, an upper reinforcing rib which extends from that edge of the window corresponding to the upper edge and a lower reinforcing rib which extends from that edge of the window corresponding to the lower edge, - at least one hinge (212a-b), where each hinge (212a-b) comprises a fixed part in the form of a female clevis attached to the upper reinforcing rib along the upper edge of the fixed cowl, a movable part in the form of a male fitting attached to the reinforcing rib of the movable cowl, where the movable part is accommodated in the fixed part, and a pin mounted between the fixed part and the movable part and in which each pin is parallel to the upper edge, - at least two locks (220a-b) arranged along the lower edge of the movable cowl, where each lock (220a-b) comprises a first part secured to the lower reinforcing rib, a second part secured to the reinforcing rib of the movable cowl, locking means that are able to move between a locking position which locks the first part and the second part to one another and an unlocking position in which the first part and the second part are free with respect to one another, and actuation means that are provided in order to move the locking means from the locking position to the unlocking position and vice versa, - a fitting to which are attached the fixed parts, - a fitting to which are attached the movable parts, - a fitting to which are attached the first parts and - a fitting to which are attached the second parts, and