On June 13, 2005, Beechcraft announced at the Paris Air Show that it was developing the King Air 350ER version of the B300, an equivalent to the earlier Model 200T and B200Ts of the 200 series.
13. juunil 2005 teatas Beechcraft, et arendab King Air 350ER versiooni, mis on samaväärne 200-seeria varasema mudelitega 200T ja B200T.