(Updated on January 24 to include detail on design changes and plans for more test airplanes)

Mitsubishi Heavy Industries (MHI) and subsidiary Mitsubishi Aircraft have delayed first delivery of the MRJ90 from mid-2018 to mid-2020 due to what they characterized as revisions to certain systems and electrical configurations to meet the latest certification requirements. Mitsubishi already stood liable for four major delays of the MRJ90, the most recent of which moved planned certification from the second quarter of 2017 to the second quarter of 2018. If this latest schedule setback proves the last, the MRJ would reach the market some seven years later than originally planned at its program launch in 2008.

Speaking with reporters during a Tuesday conference call from Tokyo, Mitsubishi Aircraft vice president of sales and marketing Yugo Fukuhara said that the latest delay stems from the design’s placement of certain components and wire harnesses in the airplane’s avionics bay. During a review last autumn, certification authorities determined that the design did not properly account for “extreme situations” such as water leakage or an explosion in the area, he explained. Mitsubishi has already started a new preliminary design review and expects to start the new design’s critical design review in a matter of months, said Fukuhara.

Mitsubishi stressed that because the design change will not affect the airplane’s performance, fuel consumption or systems functionality, the four flight-test airplanes already in operation will continue their duties as planned and that certification data gleaned from those tests remain valid. However, Fukuhara added that Mitsubishi possibly would need to add new flight-test airplanes to the program to test the new design. “We will make aircraft to test these design changes,” he said. “But we will determine later how many additional aircraft will be used.”

Although Fukuhara would not disclose the estimated costs associated with the latest delay, he insisted that MHI “can afford and can accommodate all the costs of development.”     

Separately, MHI said it established a so-called business promotion committee chaired by its president and CEO, Shunichi Miyanaga, to oversee the program as of last November 28.

“Since the historic MRJ first flight in November 2015, we have made significant progress in both engineering and test, and now three aircraft are in flight test in the United States,” MHI said in a statement. “Going forward, under the MRJ Business Promotion Committee’s oversight, we will continue to make prompt decisions and remain firmly committed to the development of the MRJ to offer our customers an aircraft with world-class performance and compatibility with latest industry certifications.”

Of the program’s four flying prototypes, three participate in trials at Grant County International Airport in Moses Lake, Washington, where the company plans to conduct most of the flight testing for certification. Processing of flight-test data takes place at Mitsubishi’s engineering center in Seattle, established in August 2015 in collaboration with locally based AeroTec specifically to administer MRJ testing in the U.S. A fifth prototype will remain in Japan to conduct autopilot tests.

All Nippon Airways remains the program’s launch customer. However, even before the last delay, it remained unclear when the two customers that account for most of the MRJ’s backlog—SkyWest Airlines and Trans States Airlines of the U.S.—would take their first MRJ90s. In fact, the MRJ90 still does not fit within the weight limitations stipulated by pilot union scope clauses among the big three U.S. network carriers, leaving SkyWest and Trans States unable to commit to firm delivery dates. Meanwhile, Embraer has moved back its schedule for entry into service of the new E175-E2 by about a year, from 2020 to 2021, for the same reason.

Most recently, Delta Air Lines pilots on December 1 ratified an agreement that maintains the 86,000 pound mtow and 76-seat capacity limits on airplanes operated by their regional affiliates until 2020. A contract extension that maintains similar restrictions reached with United Airlines pilots in January runs until 2019, while American Airlines’ contract becomes amendable in 2020.

Fukuhara insisted, however, that the circumstances surrounding the scope clauses did not influence Mitsubishi’s decision on the length of its delay. “This revision [resulted from] the design change, and has no relationship with the scope clauses,” he concluded.