JimL,
there are some SE helicopters with SAS and Autopilot. We had a As350b3 with sas and autopilot some years ago. I think this is not an issue. Any manufacturer would be interested to install SAS and autopilot on their SE helicopters to make them IFR capable.

H.

There are also a bunch of Robinsons, maybe there lies your answer.

PM your email address and I'll put something together via Dropbox, have RFM and ground training manuals etc

It's about controllability without hydraulics and secondary electrical generation requirements.
I was flying a Bell 206L-3 in the early 2000s that was fully IFR certified, of course the additional weight (plus my "skinny" med crew) prevented any sort of realistic IFR fuel load) for most of the legs we flew.
We did regular RT in the hood without hydraulics (SASless can confirm). SAS and autopilot alone do not meet the criteria, otherwise every lightweight 206L-1 or Crapstar 350 could be certified.

1. There are single engine helicopters with dual hyd. (EC130, and some AS350B3e)
2. Secondary electrical generation: it is possible to install 2 generators on the same engine like it is used on airplanes like TBM850 or Pilatus 12 etc.

I can't see the problem..

Lots of IFR training in SE, doesn't make them suitable for actual hard IFR though.

Prolly the same reasoning that says singles shouldn't be used for ems/night/nvg/SAR. What are the stats, exactly - how many machines have been lost due to engine failure, as opposed to mgb, tail rotor, drive shaft etc failure? Vested interest here, been flying single ems/SAR for a decade now, maybe time to quit...

Usual reason for EMS singles having accidents is CFIT or inadvertent IMC in an under-equipped machine.

Just to correct a couple of points firstly the bit about single engine aeroplanes flying at 25,000 feet kinda excludes all the PA 28's and other small fixed wing aircraft that regularly fly IFR in IMC at much much lower levels all without issue,not to mention the cloud base will be the same no matter how high you started from, and I would much rather pop out low level in a slow helicopter than a fast plane.

Secondly speaking from experience a stabilized helicopter is a lot easier to fly in IMC than an un-stabilized aeroplane , and even without SAS it's not a huge problem for short periods of time so long as you keep it simple and ask for help as you would only be IMC without SAS if you had a problem

I think the bigger issue is a lack of experience among the helicopter community of flying in IMC on shore, which has produced and maybe rightly so a very adverse opinion to it, where as in the fixed wing world it's just normal. The other thing to consider is that if it was easier to certify singles for IMC the equipment in them would rapidly improve as would skill and experience levels, lets not forget no one is going to force anyone to fly anything in IMC if they don't wont to! its about providing a means that minimizes risk for those who do want to

CBS

yes totally agree