Mitsubishi on Monday confirmed weekend press reports out Japan that it has communicated with MRJ launch customer All Nippon Airways about another possible delay in first deliveries due to “technical reasons.” If the manufacturer fails to deliver the first airplane by mid-2018, it would mark the fifth major delay for the troubled program.

In a written statement to AIN, Mitsubishi Aircraft insisted that it has not definitively told ANA that a delay will occur, however.

“Regarding the article on the delivery schedule to ANA, this is not based on our company announcement,” said a Mitsubishi spokesperson. “It’s not just on technical matters that we are constantly in consultation with them, and it is true that we have spoken to them of a risk of delay due to technical reasons.

“We are moving forward day by day with verification. If any decisions are made on important items to be made public in the future, we will announce them promptly,” she concluded.

The first Mitsubishi MRJ flight-test airplane landed at Grant County International Airport in Moses Lake, Washington, Wednesday evening for the start of its next phase of certification testing following a three-and-a-half-day trip from Japan. The trip marked MRJ FTA-1’s third attempt to fly to the U.S. to begin a planned regimen of trials out of Moses Lake, where Mitsubishi has established a new engineering facility from which to base flight testing of the first four prototypes. The company aborted attempted ferry flights of FTV-1 to the U.S. on August 27 and 28, when it detected anomalies in the signals generated by sensors monitoring the airplane’s air management systems. It has since replaced the faulty sensors and completed inspections to ensure the problem does not recur.

Mitsubishi conducted the first flight test of the fourth MRJ out of Nagoya Airport in Japan on September 25.

Mitsubishi already stands 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.

Confirming the latest delivery-schedule revision last December, Mitsubishi acknowledged that a new program review reflected additions to and revisions of original test items, as well as its joint engineering work with U.S. partners aimed at ensuring a “better-integrated” aircraft. The review resulted in a new MRJ development structure intended to ensure “prompt execution” of all activities, with roles and responsibilities assigned among three engineering bases in the two countries.

Tokyo-based Mitsubishi Aircraft looks after type certification documentation and coordination with airworthiness authorities, flight tests, manufacturing preparation and customer support. In the U.S., the Seattle Engineering Center has taken over design development and responsibility for innovating technological“solutions.”

This fourth MRJ delay, which followed discussions with U.S. partner AeroTec, had allowed for at least a two-month test schedule buffer. U.S. flight tests and support, including data analysis and report writing, takes place at AeroTec’s Moses Lake Test Center at Grant County International Airport in Washington state. AeroTec provides data analysis, FAA certification and flight-testing services to manufacturers like Honeywell and Lockheed Martin and aircraft modification companies such as Aviation Partners Boeing and Raisbeck Engineering.

After consulting AeroTec, Mitsubishi took what it characterized as a more realistic approach to scheduling the MRJ flight-test program. Discussions had stimulated caution last year as the manufacturer approached the MRJ’s flight readiness. A thorough review identified a number of different items added to pre-flight test work.