Mitsubishi Aircraft has conducted its first off-site test campaign for the MRJ regional jet at Rockford International Airport outside Chicago to collect data in natural icing conditions, the company announced in its latest edition of its monthly newsletter. The exercise builds on recent testing activities at Mitsubishi’s flight test center in Moses Lake, Washington, where three MRJ prototypes participate in an extended flight-test campaign now expected to last until 2020. Next, Mitsubishi plans to take FTA-4 to Florida for extreme temperature testing at Eglin Air Force Base.

The milestones come as Mitsubishi prepares to add at least one more flight-test airplane to its original complement of five following another delay to the program that will see first delivery moved from mid-2018 to mid-2020 as the company revises certain systems and electrical configurations to meet the latest certification requirements. 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 of the avionics bay. 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 Mitsubishi Aircraft vice president of sales and marketing Yugo Fukuhara.

The company has said 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, it added it 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,” said Fukuhara. “But we will determine later how many additional aircraft will be used.”

Meanwhile, Mitsubishi on Monday addressed Japanese media reports referencing changes in the production plan, noting that they revealed nothing inconsistent with the program update the company issued on January 23.

“It is true that the program schedule revision entails a change in the production schedule,” the company said in a written statement issued February 27. “As the first delivery is now revised to start in 2020, the monthly production rate will be low for the start-up period of manufacturing. After that, the plan calls for the production rate to be stepped up in a phased manner.”

The company added that it continues to review plans for when production rates will eventually reach 10 per month and that it “will adjust and reflect as we move forward with the revised schedule” to respond to customer needs and market demand.

“We are also communicating well with our partners by sharing the latest plan, and we plan to make individual adjustments with each partner based on their individual circumstances,” it concluded.