Updated January 6 with details on structural reinforcement work

Mitsubishi Aircraft and Mitsubishi Heavy Industries have delayed the development schedule of the MRJ by another year following their recognition of “several issues” during the course of engineering work with experts in the U.S., the companies announced on December 24. Consequently, expected first delivery to Japan’s All Nippon Airlines has shifted to the second quarter of 2018, nearly five years later than the original target date set at program launch in 2008.

The announcement comes only a month and a half after the first MRJ prototype made its maiden flight from Nagoya Airport in Japan. Since then the companies announced that the airplane flew at least two more times, on November 19 and November 27.

The last program schedule called for certification in the second quarter of 2017, a date that remained unchanged following the last two delays to first flight. In April the companies announced a delay from the spring to “September or October” due to a need to review the structural strength of the ram air turbine (RAT) and address certain software bugs. Then, in the last week of October a problem with the MRJ’s rudder pedal forced the new regional jet’s manufacturer to reschedule first flight for the week of November 9. It finally took to the air on November 11.

“The first flight and the subsequent flight tests have confirmed the basic characteristics to be satisfactory,” said the companies in a joint statement. “However, we also have recognized several issues as we attempt to accelerate our development.

 “Specifically, in the progress of our engineering work together with experts in the United States, we have made additions to and revisions of test items in order to complete a better-integrated aircraft. These have been reflected in the new delivery schedule. In addition, we have undertaken an overall review with our partners, and reflected this in our development schedule.”

Those need for some of those revisions became evident as early as last spring, when certain airframe components, including the wings, didn’t respond as expected to greater than normal loads, according to a statement sent to AIN by Mitsubishi Aircraft. “As for the airframe, strengthening of the wing is among the details of the changes we are making based on test feedback,” said Mitsubishi. “Also we are strengthening the fuselage after the test feedback. We have been reinforcing these components, as planned after the first flight. This kind of reinforcement work is something that happens in development work.”

Other improvements under way include “upgrades” to avionics, the flight control system and the engine control unit. “The results of static strength testing are being reflected by strengthening the airframe and the software is being upgraded that is built into the airframe system,” it added. “We are scheduling about two months for this work.”

The company added it would carry out the planned flight test campaign in North America “as soon as feasible.” It last said it would start certification flight testing in the U.S. during next year’s second quarter.

Mitsubishi decided to conduct much of the MRJ’s flight-testing at Grant County Airport in Moses Lake, Washington, in the U.S., to take advantage of its long runways and lack of regular scheduled airline service. Other testing sites in the U.S. include Gunnison-Crested Butte Regional Airport in Colorado, where they plan to conduct high-altitude takeoff and landing tests. Meanwhile, they have chosen Roswell International Air Center in New Mexico for special runway tests and McKinley Climatic Laboratory in Florida for extreme environment testing.