MIAMI — Japanese manufacturer Mitsubishi Aircraft Corporation (MAC) has resumed its flight test program for the MRJ90, ending a  ~20-day period of suspension after last month’s engine shutdown incident. On August 21, 2017, an MRJ90 outfitted with a Pratt & Whitney PW1200G geared turbofan (GTF), suffered an engine shut down while flying off the Oregon coast, requiring an emergency landing in Portland. Over the last three weeks, MAC has investigated the issue, and according to a spokesperson from MAC, the shutdown was a one-off, isolated incident:

“While we are still in the final stage of the investigation of the cause [of the engine shutdown]. Current analysis tells us that the incident from August… is isolated and the rest of the MRJ flight test aircraft were inspected and cleared as not affected.”

According to MAC, one of the four MRJ90 aircraft based its US test base in Moses Lake, Washington re-started flight testing last week. A second aircraft flew on Monday, September 11th, and the remaining two flew yesterday.

MAC started flight testing prior to the 2017 Paris Air Show (PAS), giving hope that a program which has suffered the most severe delays of any major developed world commercial aircraft project was finally on track.

The hellacious development process for the MRJ has seen numerous delays for a variety of technical reasons, and the type’s entry into service (EIS) with All Nippon Airways (ANA) is scheduled for 2020, more than seven years after it was originally intended.

Unfortunately, EIS by itself won’t be a panacea for the MRJ, as the required scope clause relaxation that was hypothesized in the United States hasn’t come to fruition. The MRJ is simply too heavy to operate in US regional carrier fleets under current contracts, and this issue puts close to 70% of the MRJ’s order book at risk.

The same issue does not currently exist in Japan, so the one saving grace for MAC is that it does have a bit of time to explore its options before its first delivery to a US customer comes due. Still, its engineers must execute a flight testing program while simultaneously look for ways to pull weight off of the aircraft.

That is not an easy tightrope to walk.