Sorry I cant see how any student cannot pull the cylic back after dumping the lever. In the types i teach on 300/500 if you dont pull the cylic back as the lever goes down you will be at about 40 degrees pitch down within a couple of seconds. So cant see how anyone can teach not to bring the cylic back, let alone a student not realising the ac is in an apparent vertical descent. Most low rrpm crashes I suspect are from people flaring way too high and pulling the lever up way to early. Most single engine machines ( unless 206 and R44) need to be flared at under 50 ft with a hard flare nice check and level followed by a cushion on to the ground