Mitsubishi Uses Precision To Cut MRJ Costs

By Bradley Perrett
Source: Aviation Week & Space Technology
October 07, 2013
Credit: Bradley Perrett/AW&ST

The card that every new commercial aircraft should get to play is a decisive rise in operating efficiency. Being new, the airliner should offer fresh technology that lets it transport passengers for less expense. For a mature rival program, a card to play in reply is low manufacturing cost. Having slid well down the learning curve, it can, if necessary, be priced more cheaply than the fancy new competitor.

It is not working out quite like that in the regional jet market, however. Because of more than three years of development delays and a vigorous technological response by an established competitor, Mitsubishi Aircraft's forthcoming MRJ may quickly lose much of its efficiency advantage. First delivery for the MRJ program is now due in mid 2017, but by 2020 a heavily updated version of the most closely comparable Embraer E Jet should go into service. The Embraer 175-E2, as it is called, will reply not only by adopting the MRJ's engine; but it will also have improved avionics and, most notably, a new wing (AW&ST Sept. 23, p. 18).

But it turns out that Mitsubishi Aircraft has another card up its sleeve. The company says the MRJ has been designed to very high levels of precision, with the aim of easing assembly and thereby cutting production costs from the very beginning of the manufacturing program. No cost figures are available, but evidence of high-quality manufacturing was apparent when Aviation Week last month saw fuselage major assemblies of the first prototype, built by airframe contractor Mitsubishi Heavy Industries. Other cost savers will be a moving assembly line and oven-cured composite parts.

MRJ development costs, meanwhile, are rising by about ¥20 billion ($200 million) in engineering salaries for each year of delay, says Mitsubishi Aircraft President Teruaki Kawai. Since the original budget for a five-year, nine-month program with entry into service at the end of 2013 was ¥150 billion, development now looks like it will cost ¥220 billion, though Kawai says that can be easily absorbed in a program with decades of production life.

Production engineers at MHI are making use of the extra time by driving more risk out of fabrication and assembly processes—probably not a small benefit for a manufacturer that is not skilled in making all parts of commercial aircraft. The program can hardly afford manufacturing foul-ups after suffering the development delays, which were mostly caused by Mitsubishi Aircraft's lack of experience in airworthiness certification (AW&ST Sept. 9, p. 50). Three customers are awaiting delivery of 165 aircraft from the program, which so far is developing the MRJ70 of 76 seats and MRJ90 of 92 seats, the latter attracting the most demand.

From the outset, the program envisaged high costs for design and early fabrication of detail parts in return for permanent savings in assembly. The idea is simply to design and build the aircraft with tighter tolerances than are normal in commercial aircraft so that parts fit together better, greatly reducing the time taken by adjustment, such as shimming. The tolerances of detail parts in the MRJ are typically only half of those normally used in other manufacturers' programs, says Hiroyuki Tatsuoka, deputy director of MRJ manufacturing assembly at MHI, declining to give details.

As production proceeds, the cost of fabricating highly precise parts will quickly fall to normal levels, says Kawai; making them does not take more machining time than less-exact components do. Rather, the main cost has been the greater engineering effort in designing the aircraft for higher precision. But that is a once-only burden on the program, whereas quick and easy assembly will be a cost saver until the last MRJ or MRJ derivative is built. The benefits are not just in final assembly, usually thought to account for about 5% of commercial aircraft costs, but also in making the major assemblies, such as fuselage modules, and also subassemblies.


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