Had a couple myself!
First was in a Bell 205. The main gearbox started to break up and the drive output to the tail rotor drive shaft failed. Force landed with power on in a dry river valley.
Second was in an AS 350B. I only had 12 hours experience on it when the last meter or so of the back end came off.
The thing that I remember the most during both incidents was the level of vibration which I would describe as ‘significant’.
In the 205 I was able to roll off the throttle as I came into the hover and land without too much trauma.
On the Squirrel it was a lot more frightening. I had to shut the engine down to stop the rotation. I knew I had lost the tail as I could see it falling like a Sycamore leaf every time we rotated past a northerly heading. Also saw my life flash before my eyes and even had a chance to regret not seeing my unborn child.
I was in rugged terrain and ended up parked nose up on about a 60 degree slope. The blades hit the hill side and stopped suddenly. My stumpy tail boom dropped with a thump and dug into the hill side and helped stop me tumbling. A giant crack started at the nose of the cabin and ran slowly back across the roof of the cabin; so much for the strength of fibre glass.