Mitsubishi confident in Geared Turbofan for its regional jet

By Tom Risen|July 19, 2018

Regional jet makes airshow flight debut at Farnborough.

FARNBOROUGH AIRSHOW, U.K. – Mitsubishi Aircraft Corporation is confident that compressor-related problems found in some Pratt & Whitney geared turbofan engines will not affect their Mitsubishi Regional Jets which are scheduled to enter production in 2020 with a newer version of the engine.

The 2020 target date gives Mitsubishi and Pratt & Whitney time to learn and adapt from the performance lessons of earlier versions of the engine, said Alex Bellamy, chief development officer for the Mitsubishi Regional Jet, in an interview.

Pratt & Whitney said in February that a handful of geared turbofan engine failures, none of which caused injuries, were due to a faulty knife edge seal in the High Pressure Compressor aft hub. The European Aviation Safety Agency cited the failures, and some A320neo planes were grounded for inspections. Pratt & Whitney said the problem was discovered only in “a limited subpopulation of engines.”

“That knife edge seal problem doesn’t affect our program at all, we have no impact,” said Bellamy, who receives reports from all engineering directors on the regional jet.

The geared turbofans are central to the company’s business strategy for the MRJ aircraft, which will be the first passenger airliners built in Japan since the YS-11 turboprops first produced in 1962. The first MRJs will be delivered to Japan-based All Nippon Airways, although the company is marketing the MRJ internationally.

“We are the last player to try to enter this market, we need to differentiate from Bombardier or Embraer,” said Hitoshi Iwasa, chief operating officer for Mitsubishi Aircraft, part of Mitsubishi Heavy Industries, which also makes fan cases for the geared turbofans. Iwasa said the geared engine is attractive because of its fuel efficiency and noise reduction.

A prototype of the MRJ made its airshow debut here at Farnborough this week partly to demonstrate the noise reduction of the plane’s geared design, called the PW1200G. This is a smaller version of the PW1100G-JM engines that experienced the seal and compressor-related issue.

The geared design adds a mechanical gearbox to a conventional turbofan so that the front fan can turn at a slower speed than the interior turbine. This slower rotation enabled Pratt & Whitney to increase the length of the fan blades and fan diameter, increasing the bypass ratio, a measure of thrust efficiency. The slower rotation of the front fan also reduces the noise of the fans.

The 1200G engine is custom built for the Mitsubishi Regional Jet. Mitsubishi says the plane will burn 20 percent less fuel than others in its class by pairing geared engines with an innovative fuselage shape and wings and tail fins that are longer than those of the average regional jet.

Iwasa said the MRJ prototypes will continue test flights until the end of 2019 in Washington state, where Iwasa is the director of the Moses Lake Test Flight Center.

In the photo above, a prototype of the Mitsubishi Regional Jet makes its airshow debut July 18 at Farnborough Airport in the U.K. (Photo by Tom Risen)