Mitsubishi MU-300 Diamond

Hawker 400
Raytheon Aircraft Beechjet 400A
Role	Business jet
Manufacturer	Hawker Beechcraft
First flight	29 August 1978 (as Mitsubishi Diamond)
Status	Active Service
Primary user	NetJets Europe
Produced	1978-2009
Number built	951 : 92 Mitsubishi MU-300, 859 Beechjet 400
Unit cost	$7.4 million USD (as of 2009)
Variants	T-1 Jayhawk

The Hawker 400 is a small twin-engine jet corporate aircraft. Initially designed and built by Mitsubishi, it has been further developed and updated by the Beech Aircraft Company, now part of Hawker Beechcraft.

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"). The aircraft first flew on 29 August 1978. It 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.

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.

Raytheon/Beechcraft steadily developed their own improvements to the model, leading to the 400A in 1990. Improvements in the 400A include longer range, higher take-off weights and improved luxury appointments. An all-glass flight deck was also offered. Beechcraft also developed a version for the United States Air Force known as the T-1A Jayhawk, used as a trainer for large aircraft crews (such as tankers and strategic transports). A total of 180 T-1A trainers were delivered between 1992 and 1997. Another military variant is the Japan Air Self-Defense Force 400T trainer which shares the same Type Certificate as the T-1A.