The Nextant 400XT is a Beechjet 400A/Hawker 400XP with new Williams FJ44-3AP engines, a new Pro Line 21 avionics suite and a new cabin interior.
The Raytheon Beechjet 400/400A evolved from the Mitsubishi Diamond 2 design that was bought by Beech in the mid-1980s.
The original Mitsubishi MU300 Diamond 1 flew for the first time in August 1978. In 1986, the Diamond 2 replaced the Diamond 1; however, only 11 Diamond 2s were built before Beech purchased the design and production rights. The Diamond 2 was renamed the Beechjet 400.
Beech equipped the Diamond 2 with JT15D5 turbofan engines, developed a new interior, and made other minor changes.
The new Beechjet 400A has a higher maximum takeoff weight and greater operating ceiling along with improved performance. Moving the rear fuselage fuel tank increased cabin volume. The flight deck features a Collins Pro Line 4 electronic flight instrument system avionics suite.
Raytheon renamed the Beechjet 400A in 1996, and produced the Hawker 400XP in 2003.
The new Williams FJ44 engines provide considerable performance and economy advantages over the JT15s.