My dad was a CFII in the USA and in Oz.
I know of a story where he had an engine failure in California and commenced an Autorotation, thing is the student locked up and refused to let go of the controls so Dad persuaded him to let go ( I think that was by way of a gentle tap ) ...anyway he landed it with the student still trying to maintain control and he ended up getting it on the cliff edge...the helo I think was a H269 and ended up sliding off the cliff edge but hung on by a skid.
Both pilots climbed out and I think Dad had a few bevvys that night.
Not sure if the student flew again but Dad sure did.
This was in the early 80's I around 79 to 81 from memory ... I was but a wee tacker but the story remains.
It was in the paper and I think my Mom still has the newspaper clipping.
I could get more info if need be.
HF