Shaft assembly for an aircraft engine

An assembly for an aircraft powerplant, the assembly comprising:

• a rotational load;
• and
• a shaft coupled to the rotational load, the shaft extending along an axis between and to a first axial shaft end and a second axial shaft end, the shaft including a slotted axial segment extending circumferentially about the axis, the slotted axial segment extending axially between and to a first segment end and a second segment end, the slotted axial segment forming an axial portion of the shaft, the slotted axial segment having an outer diameter surface, a diameter of the slotted axial segment having a maximum at the first segment end and the second segment end and a minimum at an axially-intermediate position between the first segment end and the second segment end, the slotted axial segment having a convex profile facing radially outward from the shaft, the convex profile extending between the first segment end and the second segment end, the slotted axial segment including a first circumferentially-continuous body portion and a second circumferentially-continuous body portion, the first circumferentially-continuous body portion forming the first segment end, the second circumferentially-continuous body portion forming the second segment end, the slotted axial segment forming a plurality of slots extending lengthwise between and to the first circumferentially-continuous body portion and the second circumferentially-continuous body portion, the plurality of slots extending radially through the outer diameter surface, the plurality of slots being arranged as a circumferential array about the slotted axial segment.