Yeah it definitely looks like the crank pin let go. I can see the same thing that proptop was talking about with the rust build up. Funny thing is when the NTSB is doing a full size aircraft accident investigation that is one of the things they lok for when mechanical failure is suspected. One of the few things I remember from a college class I took a "few" years ago. I also have a motor, a Thunder Tiger Pro .46, that has over 25 gallons through it with bearings that look similar to those pictured. It still turns free and runs fine. It could use a new set of bearings but I am not sure it worth spending the money are a motor with that much time on it.