https://data.ntsb.gov/.../GenerateNewestReport/102076/pdf

Ran across this report and was wondering if anyone has any additional info of this?

There have been 18 failures of valve spring retainers. 7 to 2000 hours. This recent one brought the plane down, thankfully no one was hurt but this is concerning since I can't seem to find any info on service bulletin info, other than a proper oil purge, which according the this NTSB report may or may not be the issue.