Don't be daft. Roll to idle, friction up, get out and shut the door.
FHM says nothing about this at all. Check your op's manual thou. 407 too knows a thing or two about flying, I would suggest you take his advice over any of the english pilots who have responded.
ie:
"What if there turbine decides to run-way up?"
What is a run-way up? Oh! you mean a highside failure... Not going to happen unless you roll on the throttle and in all the JR hours I have flown and all the JR pilots I have chatted with, I have never heard of this happening.
"What if one of the control servos decides to have a "stroll"
Where would it go? The rotor system will not change its plane of rotation unless acted on by a force on the cyclic. Frictions ON! Some say that you should switch off the HYD but that is a load of bolloks too. Makes no difference. HYD are just power steering like your car and you leave that idling at the shopping mall.
"What if there is a fluky gust of wind. 407 too suggests "flight idle, friction locks on. (wait for rpm to run down)" - Blade sailing is far more pronounced at lower rpm"
This is a Bell not a Sikorsky or Hughes.
As a sidenote, I worked for a tourism operator once upon a time who left the machine running while you escorted your pax around a tourism attraction. I think the total distance was about half a kilometres walk (plus the climb up the hill
) from the machine. It was always interesting to see if it was still there 20mins later. Once in a while the wind would shift and a reassuring whine would float down the hill...
Each to their own.
PS: if you shut down and it won't start. Tap the starter with something solid - axe, piece of wood etc and then try the start, Still nogo? Repeat the above with one of the customers finger on the start button (NOTE: thottle off!) Usually it is the brushes that will cause starter failure.