The Mitsubishi Aircraft Corp. is working on improvements to the MRJ70, which will be the second version of the MRJ regional jet to enter service, and is looking increasingly important. The company has hinted at improvements in operating efficiency for the 76-seat version, although it is not moving delivery targets.

The MRJ program is 80% through flight testing of the initial version, the MRJ90, which is designed to seat 88 passengers in an all-economy arrangement. So far, there have been no major surprises. Since the company flight testing phase is almost finished, there is not much time now for any to appear. The next phase is type-certification flight testing under the eye of the Japan Civil Aviation Bureau (JCAB).

After five delays, launch customer All Nippon Airways is scheduled to receive its first aircraft in mid-2020, about 6.75 years later than was intended when the program began in 2008.

Mitsubishi Heavy Industries (MHI) is majority owner of Mitsubishi Aircraft and makes the MRJ structure; the engine is the Pratt & Whitney PW1200G.

Four prototypes, built with the MRJ90 design, are operating at the main flight-testing base, at Moses Lake, Washington. A fifth has been kept on the ground at the program’s home at Nagoya, Japan, while two more, late additions to the development effort, are close to entering final assembly and will fly next year.

The MRJ70 is running a year behind the MRJ90 in development, implying a 2021 first delivery, though the company said the timing of the first flights for the two prototypes of that version will be determined by market requirements in 2022.

By then, 14 years will have passed since program launch. Moreover, the MRJ70 looks like it will become the main version for the key North American market, because pilot contracts with big US airlines still preclude them from letting subcontract airlines use aircraft as heavy as the MRJ90.

“A lot of our focus is on what improvements need to be implemented into the MRJ70 to make sure the economics, passenger comfort and environmental performance are best in class,” the company said, without giving details.

The extra two MRJ90 prototypes were added to the program to incorporate a revised design that the company realized in 2016 was necessary to remove a risk to certification. Mitsubishi Aircraft at first planned on 2,500 hr. of flight testing; it added 500 hr. to its estimate when the design changed. The aircraft have clocked up 2,400 hr. so far.

“The company flight testing is nearly completed,” Mitsubishi Aircraft said in written answers to questions. “We haven’t experienced any significant variances from our predictions during testing and any small things that have been found have been optimized as much as possible.”

The JCAB has agreed to use data from company testing in the certification process.

Working out procedures for ideal takeoff and landing performance has been a focus in the past few months. Avionics supplier Rockwell Collins has been involved in what Mitsubishi Aircraft calls the tuning of pilot procedures. Separately, drainage has been evaluated: using colored liquid, engineers have verified that leaking fuel or hydraulic fluid will flow out of the aircraft, not accumulate in it and create a hazard.

The prototypes are overweight, as prototypes usually are, but the company said weight reduction is part of its plans for continuous improvement.

Bradley Perrett/Aviation Week