In 2003 the Japanese government started a five-year, $420 million research program to study an indigenous regional jet for 30 to 90 passengers, led by Mitsubishi Heavy Industries (MHI). In 2004 MHI was focused on a 2m high by 2.8m-wide, four-seat abreast cabin, seating 30 to 50 passengers, and was hoping to fly a prototype in 2007 and deliver the first aircraft in 2010. In 2005 it switched to a larger 70-90 seat category.
MHI launched its concept at the 47th Paris Air Show in June 2007, showing a full-scale cabin mock-up and aiming to be the first regional jet all-composite airframe, with certification targeted for 2012. Mitsubishi formally offered the MRJ to airlines in October 2007, the first Japanese airliner since the NAMC YS-11 production stopped in 1974, after being the first airframer to select the Pratt & Whitney PW1000G geared turbofan offering a 12% reduction in thrust specific fuel consumption, rated at 15,000 lbf thrust on the 70- to 80-seat MRJ70 and 17,000 lb thrust on the 86- to 96-seat MRJ90, projecting a $1.275 billion development cost.
MHI officially launched the Mitsubishi Regional Jet Program on March 28, 2008 with an order for 25 aircraft (15 firm, 10 optional) from All Nippon Airways, targeting a 2013 introduction. Mitsubishi is targeting a 20% share of 5,000 sales forecast in the 70-90-seat bracket over 20 years. Flight testing was scheduled for late 2011 and the $1.9-billion programme necessitates 300-400 sales to recoup its cost.
In September 2009 Mitsubishi unveiled extensive design changes, using aluminium instead of carbon fibre composites for the aircraft's wings and wingbox; the remaining composite parts will make up 10-15% of the airframe: the empennage. The cabin height is increased by 4 cm to 204 cm and the fuselage height is increased to 296 cm, giving a rounder cabin, wider and higher than its competition. The program was delayed six months with final design frozen in mid-2010, first flight delayed to the second quarter of 2012 and deliveries to early 2014. Maintenance intervals are 750 flight hours per A Check and 7,500 flight hours per C check.
As the MRJ90 MTOW of 39.6 tons is above the US regional carriers scope clause of 39 t, SkyWest and Trans States Holdings could convert their MRJ90 orders for 100 and 50, respectively, to the 1.4 m shorter MRJ70: 67% of the 223 firm MRJ90 orders. But the MRJ70 seats only 69 in two classes and attain the 76 seats scope close limit only in all-economy: Mitsubishi wants to increase seating within its fuselage to compete with the currently compliant Embraer E-175 and Bombardier CRJ900. Mitsubishi is working on a three-class, 76-seat design, with more premium seating than the MRJ70 but still within the scope-clause 39 t MTOW, which was unveiled at the June 2019 Paris Air Show. The reworked MRJ70 will be called the Space Jet M100, its type certificate is expected in 2022
In early 2013, Pratt & Whitney delayed the PW1200G certification to the "latter half" of 2014, after the MRJ first flight scheduled for late 2013. On 22 August 2013, Mitsubishi announced a third delay to the program, and that the first flight would take place in the second quarter of 2015 instead of end-2013, while the first delivery to launch customer ANA would take place in the second quarter of 2017 instead of 2015, due to parts delivery problems including Pratt & Whitney engines. On 7 September 2013 were exhibited a prototype of the left wing and four aluminium sections : forward fuselage, front mid fuselage, aft mid fuselage and aft fuselage, to be assembled in October 2013. Mitsubishi has hired foreign experts to help with relations with suppliers, ground tests, flight tests, and certification.
The maiden flight of the MRJ90 took place on 11 November 2015. On 24 December, Mitsubishi announced a one-year delay for the first delivery of the MRJ, to mid-2018. The delay was attributed to insufficient wing strength and the redesign of the landing gear for better safety.
In January 2017, a further two-year delay was announced, pushing the expected first delivery to mid-2020. This resulted from moving the avionics bay and wiring looms and in March the flight certification program was extended from 2500 to 3000 flying hours. Mitsubishi originally planned to use five flight test aircraft and two ground test aircraft but one or two additional aircraft will also be needed following this introduction of a latest delay.
By December 2017, the MRJ test campaign was half done with 1,500 flight hours and less than 1% cancelled due to technical issues. Their rate is accelerating with tests set up before the January 2017 avionics bay redesign: special runway tests, extreme environment and high altitude tests, were completed in 2018. An additional flight test aircraft incorporating the redesign joined the campaign in the second half of 2018, focused on wiring tests like lightning and high-intensity radio-frequency. Two additional aircraft (10007 and 10010) were completed and joined the flight test campaign towards the end of 2018.
In January 2018, the avionics bay rearrangement and rerouted wiring were almost complete to be adequate for extreme events such as bomb explosions or water ingress underfloor. Upgrades and ground tests were performed on four flight test aircraft from February to March at Moses Lake, preceding flight testing for natural icing, avionics and autopilot, performance, stability and control.
In April 2018, the test fleet had logged 1,900 flight hours. The flight-test fleet attained 2,000 hours in May 2018, and as most of the flight envelope was explored, the next trimester shifted to runway performance: take-off, landing and minimum control speeds. The MRJ70 test aircraft (number 8 and 9) were in final assembly as of May for expected delivery by the end of 2021, one year after the MRJ90 introduction. An MRJ in All Nippon Airways livery was exhibited at the July Farnborough Airshow, alongside appearances by the similar Embraer 190 E2 and larger Airbus A220.
In October 2018, Bombardier sued Mitsubishi in Seattle, alleging that its ex-employees stole trade secrets to help for US certification. By then, the four MRJ90 prototypes had clocked 2,400 hours, targeting certification in late 2019 or early 2020 and first delivery in mid-2020, while the smaller MRJ70 should be introduced in 2022. After the MRJ programme lost $439 Million for six months to 30 September 2018 on top of its $909 million deficit, Mitsubishi Heavy Industries injected $1.94 billion in Mitsubishi Aircraft, raising its stake from 64% to 86.7% and capital from $910 million to $2,5 billion. By December 2018, the Japan Civil Aviation Bureau delivered its type inspection authorisation, allowing to debut certification flight testing in early 2019 with the four MRJ90 in Moses Lake.
In April 2019, a federal judge dismissed Bombardier's claims against Mitsubishi, a strong case but falling short as there was no proof that Mitsubishi knew about those secrets. By then, the program had completed 2,600 flight hours and was undergoing crosswind and climate testing, while two more MRJ90s should join this summer.
On 24 June 2019, Bombardier and Mitsubishi announced that Mitsubishi would purchase the CRJ Programme from Bombardier for US$550 million and assume US$200 million in liabilities. With the deal, Mitsubishi will acquire the maintenance, support, refurbishment, marketing, and sales activities for the CRJ Series aircraft, including the support network locations in Montréal, Québec and Toronto, Ontario, its service centres located in Bridgeport, West Virginia, and Tucson, Arizona, and the type certificates.
In June 2019, Mitsubishi rebranded the MRJ program as the SpaceJet. The MRJ90 was renamed as the SpaceJet M90 and a 76-seat variant specially targeted to meet US scope clauses, to be known as the SpaceJet M100, was announced. This version will be 1.1 m longer than the abandoned MRJ70 but 1.3 m shorter than the M90.
The E175-E2 is heavier than the current, scope-compliant E175, with its larger GTF engines, and being longer and wider when its cabin is full, it can only fill 4 tons of fuel within the 39 ton MTOW limit, limiting its range to a short 950 nmi. Compared to the E175-E2, the M100 cabin is a tighter fit around its 76 seats, and its wing is lighter, having 3.2 m less span and with smaller winglets than the MRJ90, giving it 50% more fuel than the E175-E2 at the MTOW limit for a 1,500 nmi range with 76 passengers. Without the scope clause limit, a 42 t MTOW M100 could fly 1,910 nmi with 84 passengers. The M100 redesign pushes back its service entry to 2023, one year later than the MRJ70, while the M90 will evolve into the M200.
The 0.61 m longer fuselage can seat 88 in single-class, and at 28 m the wingspan is 1.2 m shorter with the modified canted wingtip. The shorter span will allow operating at Colorado's Aspen/Pitkin County Airport, a popular tourist destination, the only in-production jet with the capability after the CRJ700 production ends. MITAC partner Triumph Group's structural optimization should remove 15% of the combined structural weight of the wing, aft fuselage, and empennage.
A new production facility for the aircraft was built at Komaki Airport in Nagoya, Japan, on land purchased from the government at a total cost of $546 million. The 2015 roll-out of the MRJ took place at Komaki, which had previously been the development site of the Mitsubishi A6M Zero fighter.
On 26 April 2017, the fifth MRJ was complete in ANA livery, lacking only engines and nose cone, aircraft number six and seven had their fuselage and wings joined without the tails and the eighth, the first MRJ70, was at the assembly line start; Mitsubishi can manufacture 12 aircraft concurrently: in station one are joined fuselage sections, in station two the landing gear, wings and horizontal stabilisers are attached, in section three the major components are assembled, in outfitting takes place in section four and ground tests in station five, then the completed aircraft moves to painting.