One prototype of the 1960 (some sources say 1962) four-seat Kjeller PK X-2 experimental helicopter was built, powered by a 800 shp GE YT-58 turbine engine and with a 13.00 m rotor diameter.
Built with some H-19 parts, it crashed in February 1965.
Kjeller Flyfabrikk PK X-2
All Aero 