 When fitted with the new engines, the SM-2B became the SM-9, first flying in this form on 5 January 1954.The SM-9's performance impressed the Soviet authorities, and it was ordered into production as the MiG-19 on 17 February 1954, despite the fact that factory testing had only just started.The rush to get the MiG-19 into service resulted in initial production aircraft having a number of serious problems.