Painted almost exactly as it appeared in brochures seven years ago, the Mitsubishi Regional Jet is finally coming together. Major sections of the first prototype are complete and nearing the stage of final assembly, while program managers consider how quickly they can build the type to make up for extensive development delays.

Mitsubishi Aircraft and its airframe builder and major shareholder, Mitsubishi Heavy Industries (MHI), appear to favor the high end of a range of contemplated production rates, although they are wary of the ability of their supply chain to keep up.

MHI has announced its manufacturing plan for the program. The industrial giant will redistribute MRJ work around its sprawling empire of factories, including four in the Nagoya area. There will be two new production lines on or next to current sites.

Final assembly will remain at the Komaki South plant at Nagoya Airfield, the city's secondary airport, but MHI aims to build a facility dedicated to that purpose on adjacent land.

The Tobishima plant southwest of Nagoya has been building the wings and fuselages of the first aircraft; it will now be joined in that work at Oye in the southeast, where detail parts and the tail assemblies have been made. The tail work will move to Matsusaka, 75 km (46 mi.) away from the city.

A new production line to be set up at MHI's Kobe Shipyard & Machinery Works will build the spars and skins of the left and right wing boxes, and parts for the center wing box. This activity will be the only part of the airframe production setup that is not close to Nagoya.

MHI says small parts will be built at its Iwatsuka factory to the west of Nagoya and “under an industrial cluster arrangement, by partners using the Matsusaka plant.” Larger parts, presumably including sub-assemblies, will be made at the Oye plant.

The fully assembled fuselage of the first aircraft, an MRJ90, was towed out of the Tobishima factory in December, sporting the red, black and yellow livery used in depictions of the aircraft since before the program was launched in 2008.

The left and right wings are now structurally complete, says Mitsubishi Aircraft President Teruaki Kawai. “They are ready to ship to Komaki South” for final assembly of the first prototype, which is due to fly in the second quarter of 2015. Entry-into-service remains targeted at early 2017, more than three years late due mainly to problems with certification procedures.

The second airframe, one of two for ground testing, is under construction. The second and third flight-test aircraft have advanced to the stage of building up major assemblies; altogether, five are planned.

Two MRJ90s will be flight tested in Japan and three in the U.S. Flight testing of the MRJ70 will not begin until the MRJ90 is certified. The average size of the most demanded regional airliners has drifted up since the MRJ was launched on April 1, 2008, so the MRJ90 now has the higher priority. The proposed but unlaunched 100-seat version, the MRJ100, depends mainly on demand from Europe, which Mitsubishi Aircraft says remains weak. Besides, the company clearly has a big enough task getting its initial models into service without further delay.

The originally planned production rate for the MRJ was a steady five aircraft a month, but three customers are awaiting 165 aircraft that were initially supposed to begin joining airline fleets about three months ago. Last year the company said that to alleviate the problem a production rate of seven, eight or even 10 a month was possible. Now Kawai says: “Ten per month might be a good number.”

Allowing for 18 months of ramp-up from early 2017, a steady rate of five a month would clear the backlog around mid 2020, if no slots are reserved for future customers.

Mitsubishi Aircraft has previously said that one challenge in ramping up quickly is obtaining enough skilled people. Another issue is MHI's experience. Although it is quite used to such rates with its programs for making large parts for Boeing commercial aircraft, it is not accustomed to building complete aircraft of the MRJ's size nor at fast rates.

Embraer is developing a new wing for the E Jets, following Mitsubishi Aircraft in choosing an efficiently long and slim planform, and fitting them with the same Pratt & Whitney PW1200 engine that is used by the MRJ. The Japanese aircraft has thus lost much of its prospective advantage in efficiency.

Kawai says it still has some advantage, because the MRJ's fuselage has a small cross-section and therefore low drag, thanks to its baggage compartment being placed aft instead of under the floor. A skinny fuselage should tend to be heavy, but Kawai points out that Mitsubishi Aircraft is saving weight by building tail surfaces of composite.

The MRJ also has an advantage in quietness, he adds. Although the engine is the same, the Japanese aircraft's wing and landing gear have been designed to minimize noise.