If the link provided by SimFlightTest to the NTSB report on loss of Bell 206B N61PH on 16 Apr 2019 also doesn't work for others, then try this one:
https://data.ntsb.gov/Docket?ProjectID=99264
Also, this article summarises the report:
https://aerossurance.com/safety-mana...est-mast-bump/
NTSB attributed the loss to mast bumping and in turn identify probable cause as: "a result of a sudden displacement of the cyclic stick during a low-G maneuver, leading to mast bumping. Contributing to the accident were the unsecure positioning of the flight test engineer’s laptop computer and the deviation from standard operating procedures to leave the left seat cyclic control installed during the test flight".