A bearing unit having an axis of rotation (X) for a wheel hub assembly for motor vehicles includes stationary radially outer ring, a rotatable wheel hub or first radially inner ring, a rotatable second radially inner ring having an axially external first axial contact edge, an axially internal second axial contact edge having a radially external first contact surface configured to abut a surface of the first radially inner ring, a radially internal second contact surface, and a relief groove interposed radially between the first contact surface and the second contact surface, two rows of rolling bodies interposed between the radially outer ring and the second radially inner ring, and a joint including a bell, the second contact surface contacting a surface of the bell and axial locks the radially inner ring, and the relief groove reducing contact between the second contact edge and the surface of the bell.

A propeller shaft assembly for an aircraft engine includes a shaft having: an annular wall extending circumferentially about a shaft axis and circumscribing a hollowed interior defining a cavity in a front end portion of the shaft, the annular wall having an outer surface and an inner surface facing radially inwardly to the cavity; and a front flange projecting radially outwardly from the annular wall. The front flange includes a hub side surface defining an interface plane and adapted to abut with a propeller hub. The shaft also includes a reinforcement web defining an end wall of the cavity, the reinforcement web extending radially inwardly from the inner surface of the annular wall. At least part of the reinforcement web is radially aligned with the front flange. At least one perforation extends axially through the reinforcement web.