Originally Posted by
Ascend Charlie
Eddie, choppers like the R22 and R44 have a collar placed over the mixture control to prevent it being inadvertently pulled away from Full Rich while applying cyclic trim, and also to stop people leaning the mixture.
In your plank you can lean the mixture until it runs rough and then advance it a bit - the prop keeps the engine turning over if you go a bit far.
In a chopper if the engine coughs it will stop and will not restart unless the pilot takes specific actions which consume time and altitude.
Wasn't talking about manual mixture control or cutoff was referring to the Carburettor internal settings which closer to stoichiometric than rich.