The Hawker 400 (also known as the Beechjet 400) is a light business jet. Initially designed and built by Mitsubishi, it has been further developed and updated by the Beech Aircraft Company, now part of Textron Aviation. It was produced over 30 years under the names such as Mitsubishi Diamond/Diamond II, Beechjet 400/400A, and Hawker 400XP; military version T-1 Jayhawk was also produced. In total, over 900 Hawker 400s have been delivered. Since 2017, a factory-engineered and supported upgrade to Hawker 400XPR is provided, reducing fuel consumption by 16-20%, and improving range by as much as 33%. Design The Hawker 400 is a small, low-winged twin-turbofan aircraft of all metal construction, flown by a crew of two pilots and accommodating eight passengers in a pressurised cabin. Its wings use a computer-designed supercritical airfoil in order to minimise drag. Its two Pratt & Whitney Canada JT15D turbofans are mounted on the rear fuselage. The 400 can fly with four passengers, cruising at Mach 0.71–0.73, and most pilots are comfortable flying it over three hours, about cruising at Mach 0.73–0.76. Typical missions are 1.5 to 2.0 hours with block speeds. It burns of fuel the first hour, dropping to for the second. Basic operating weights range from , full tanks payload is less than with an average passenger load of three, however its full capacity is six passengers Development The aircraft was originally designed as the Mitsubishi MU-300 Diamond, an all-new, all-jet development to complement and slot above the Mitsubishi MU-2 and provide Mitsubishi Heavy Industries with their top-of-the-line corporate aircraft model (hence the name "Diamond"). It first flew on August 29, 1978. Mitsubishi chose to certificate the Diamond in the United States under FAA Part 25 regulations for transport aircraft, but additional requirements introduced by the FAA after the crash of an American Airlines DC-10 airliner at Chicago resulted in significant delays in the certification process, with the required changes to the aicraft adding , and the aircraft not receiving its certification until November 6, 1981. Mitsubishi went on to produce 97 MU-300s, all of which were assembled by the company's United States subsidiary. In 1985, Mitsubishi sold the rights and a number of unfinished airframes to Beechcraft, who began manufacturing it as their own model, initially re-designated as the Beechjet 400, certificated by the Federal Aviation Administration in May 1986. Raytheon/Beechcraft developed improvements for the 1990 400A for longer range,