The Merlin series of turboprop executive transports was Swearingen's first manufacturing program, and laid the foundations for the successful Metro series of commuters.

The improved and slightly larger Merlin III combined the Merlin II's fuselage but stretched slightly and with a new tail; and the wings and landing gear of the Metro II airliner and more powerful engines. The Merlin III (or SA226T) was certificated on July 27 1970. The Merlin III was followed by the Merlin 300 (by which time Fairchild had acquired the Merlin and Metro lines) which introduced aerodynamic improvements including winglets. Only 10 were built. 

 

 Fairchild Merlin IIIB