IS this the Scruggs deal?
Not specifically delineated but one source said she may have walked away from the plane then tried to walk back and thank the pilot from outside the plane. Perhaps she exited the starboard door, walked around in front, then approached the port side from the front, which would have juxtaposed her left arm/head with the prop diameter if she was a little too midships-wise (to her left). Being a very small airfield, apparently, lighting might not have been too good, maybe she couldn't see the prop (well, you can't see the tips as they rotate at speed anyway) and maybe the pilot couldn't see her either. Basic rule is, however, when you lose sight of each other, the pedestrian freezes, and the pilot shuts down if (s)he can't immediately regain sight of the pedestrian, right?
But still, if a proper passenger safety pre-brief had occurred, and the pilot reminded the passenger(s) about debarking when they landed, and she wasn't distracted, she would not have done that.