Things don't have to go wrong with the rotors.....
many, many years ago a pilot of a Mayne-Bristow Wessex 60 landed on a rig in Oz and shut down the starboard engine and rotor, leaving the port engine running with main drive disengaged. He nipped down for a quick pee, tea and sarnieee.... but imagine his horror when he returned some minutes later to discover that a fuel leak had caused his helicopter to catch fire
I operated in the bush in Africa for many years (yes, not just the boring drag out to offshore from Eket) but after that I always shut down to refuel from drums and mostlly to pick up pax as well (usually at the insistence of one of the clients). Always made sure that I called up base on HF so they knew where I was and approximately I'd shut down for (and in latter years we always carried a satellite phone of course). I've left the aircraft running a few times when single pilot, but only in times of really dire need, and always with frictions on (where fitted). Trouble is that in something like a 76 if you don't stop the rotor with one engine running, you could have a failure of the cyclic mag brake with rather nasty consequences (and yes despite what PPF#1 Fan says, I have had several mag brake failures
).
So, even though I had nothing to do with JAA or FAA or CAA for many a long year, I have to agree with Jim L and say that you should carry out a short risk assessment and decide whether it really, truly is necessary to leave the rotors running and leaving your helicopter. There are circumstances in which it's justified as has been pointed out by many posters on this thread and I don't disagree with it being done....... but do thimk first about the things which could go wong, because sometimes, they just do
