Probably a good thing it wasn't a nose down run away trim.
Happened to a Lockheed 18
Lodestar 50+ years ago. In this case it was an aftermarket electrical trim motor, and it ran away in the negative-G direction. An AD was soon issued to replace that motor with a less powerful one:
ASN Aircraft accident Lockheed 18-56-24 Lodestar N1000F Lake Milton, OH