Soloy Corp. has begun certification of its Turbine Pac powerplant conversion for the new Cessna 206H. The conversion installs an original Rolls-Royce 250-C20S turboprop in place of the airplane’s   Lycoming IO/TIO-542 piston engine. The Olympia, Wash., firm has delivered more than 75 turbine-powered 1977 to 1986 Cessna 206s and 207s under a current certification.