After two aborted test flights in as many days following a faulty air-conditioning system, Japan's first locally built passenger jet was back for checks and fixes amid delays to a program aimed at challenging the dominance of Brazil's Embraer SA and Canada's Bombardier Inc.

Mitsubishi Aircraft Corp, the builder of the Mitsubishi Regional Jet, will make a decision on resuming its test flight to the United States after the problem has been fixed, Spokesman Kenichi Takemori said from Nagoya on Monday. The company has delayed delivery of the aircraft at least four times. ANA Holdings Inc is scheduled to receive the first MRJ in the middle of 2018.

Mitsubishi Aircraft, a unit of Mitsubishi Heavy Industries Ltd, is trying to break the regional-jet duopoly of Embraer and Bombardier. Mitsubishi's MRJ, which can seat as many as 92 people, is getting a boost as Bombardier focuses on building CSeries jets that will be able to carry as many as 160 passengers, rather than renewing its lineup of planes with fewer than 100 seats.

The air-conditioner issue isn't likely to cause another postponement, said Kenjin Hotta, an analyst at Macquarie Capital Securities (Japan) Ltd. "It sounds like the planes will be on their way sooner or later," he said. "I am not terribly concerned."

The plane is the first of four that the firm plans to fly to the US for testing as the company works toward getting certification in the world's largest economy. It returned to Nagoya after aborting the trip mid-flight as it headed to the northern Japanese island of Hokkaido.

The consecutive disrupted journeys underscore the challenges in building and testing new passenger aircraft, which can bedevil even long-established planemakers such as Boeing Co and Airbus Group SE.

Bloomberg