from what I have been told Butson's troubles with the department arose from him not shutting the engine down during engine failure training.
his belief was that shock cooling would kill the engine. you can find the details of the ten year stouch with the department yourself.
a company favoured for their lead in training for commercial pilots here in perth has always shut the engine down in their duchess trainers. they have never had an engine die from shock cooling and in fact have taken each engine to its TBO, at last count one duchess was on I think its sixth set of engines.
there was a double fatality near perth not so long ago of two guys flying home in their reasonably newly acquired twin.
they lost an engine and it is believed that they applied the corrections to the wrong engine. it is possible that they had never experienced an actual dead engine before. both are dead so they can't tell us.
draw your own conclusions gentlemen.