MIAMI — Japan’s Mitsubishi Aircraft Corporation and Mitsubishi Heavy Industries have announced a review of the testing campaign of its Mitsubishi Regional Aircraft (MRJ), sparking rumors in the industry about a possible delay to the program.

In a brief press statement, the airframer says both companies “are now reviewing the entire schedule, from testing to the first delivery” without stating whether this may represent a potential rescheduling of the program, with deliveries set to be in the second quarter of 2017.

The announcement was made a little more than a month after the maiden flight of the MRJ from its base in Nagoya on November 11, four years after the original target date set at program launch in 2008. Since then, the program experienced two additional delays, moving the first flight to summer 2015. A third delay was announced for a few months due to technical issues. Mitsubishi also reported that the flight test campaign will continue its pace.

Rumors about a possible delay were prompted by a report from Japan’s Kyodo news agency, stating that the program would postpone the first delivery to All Nippon Airways (ANA) until 2018, without disclosing the specific reasons for this decision. Nevertheless, the manufacturer assures that the results of its assessment to the program will be disclosed before the end of this month.

The flight test campaign will use five aircraft. Three of these aircraft will perform the campaign in the United States. Last August, Mitsubishi opened the doors of its Engineering Center in Seattle, while Grant County Airport in Moses Lake, Washington, will be the Flight Test Base. The manufacturer has also chosen Roswell, New Mexico  for Special Runway Testing tests, Gunnison, Colorado for High Altitude takeoffs and landings trials, and the McKinley Climactic Laboratory in Florida for Extreme Weather Environment tests. One aircraft will remain in Japan for flight testing.

Since its announcement at the 2007 Paris Air Show, the MRJ has logged about 400 orders, mostly from American carriers. Skywest and Eastern Air Lines are two of its most important customers. The MRJ was formally launched in March 2008, and the first flight was originally scheduled for the second quarter of 2012.