Originally Posted by
hoistop
I believe there is none installed on a turbine helicopter, but piston engine ones?
As mentioned, you'd have to go back years to find vac systems in helicopters, to include turbines. For example, there was one large GOM operator that installed vacuum systems in all their 206Bs up through the 80s, early 90s. Once the cost lowered, and in some cases the reliability of the electric gyros increased, operators went strictly electric. I think you'll be hard pressed to find a vac system in any current helicopter at least on this side since the FAA streamlined the approval process to replace vacuum systems with electric flight instruments. In some cases it can be done as a minor alteration with only a mechanic's sign off.