A group of us were just having a look at Piper Cheyenne, and we were intrigued by a feature of the aileron. The trailing third of the aileron has a distinct angular bulge in both the upper and lower surfaces. This runs the full span of the aileron. There is no corresponding bulge in the flap. We were all stumped about the reason for such a feature, and although we had some thoughts, these didn't seem to fit with what was on the plane.
Does anyone have any idea what the purpose of this bulge is, and if any other aircraft have similar design features?