Baranfin,
They are connected by slip-rings (commutators) powering heated electrical mats in the same manner as heated props on fixed wing aircraft.
The Puma has had the system available for a considerable time. The 332L2 Super Puma Mk2 also has a system available.
The S92 system technology is supposedly being looked at as a potential retrofit for the S76 (depending on who you talk to), and for introduction into a new improved variant of the S76.
[ 16 November 2001: Message edited by: Cyclic Hotline ]