Complex sentence: Beechcraft bought the production rights and began manufacturing it as their own model, initially re-designated as the Beechjet 400, certificated by the Federal Aviation Administration in May 1986.
Split into simpler sentences: Beechcraft bought the production rights and began manufacturing it as their own model, initially re-designated as the Beechjet 400. The Beechjet 400 was certificated by the Federal Aviation Administration in May 1986.