Shrike Commander in Alaska crashed because it was fueled wrong.

[N1120A]

https://www.adn.com/alaska-news/avi...t-injured-pilot-and-3-firefighters-ntsb-says/

How does a pilot miss this one? Apparently, the fueled even asked about Prist.

 

[PeterNSteinmetz]

The second one was worse, a Twin Commander with two new engines got fueled with jet-A.

This seems to happen a lot to Commanders.