While doing a pre-flight this morning, I noticed that the right MLG tire looked a bit soft. So I cranked it up and taxied over to the maintenance hangar to pump it up. I shut down in front of the hangar and got out. One of the IAs was walking toward me, looking at the ground under my cowling. I followed his gaze and saw the smallest piece shown below, and said “please don’t tell me that came off my airplane.” Sadly, he said “yep, fell out of the spinner when you shut down.”
Bottom line: the spinner bulkhead disintegrated as soon as we removed the spinner. As you might notice, it had apparently been coming apart at radial cracks propagating in at least three places. I’ve been flying since 1967, have owned multiple airplanes over the years, and I’ve never seen this before.
I don’t know what would happen if the bulkhead came apart at 2500 RPM, but the wonder is that, except for needing air in the tire, I would not have seen this problem. It would at least been a BIG vibration from an unbalanced bulkhead and if that went on long enough, loss of the spinner itself seems possible. Just my lucky day.