The dream takes to the sky

The dream takes to the sky

The Mitsubishi Regional Jet (MRJ) is the first Japanese-made commercial jet in half a century

Now finally, here it is, painted in white and gray and bearing the red, black and gold house livery. Its long sleek nose points to the north. Runway 34, Nagoya Komaki Airport: The strip of tarmac stretching out in front of the MRJ90 Mitsubishi Regional Jet is 2,740 meters long. After about one and a half kilometers, the aircraft, the currently newest narrowbody, reaches its take-off speed.

It is for more than 50 years now that the Japanese aviation industry has been waiting for this moment. On August 30, 1962, the YS-11, a Japanese twin-engined turboprop airliner, took to the sky for its maiden flight. This marked the last time the Japanese aircraft manufacturers had developed, built and put into operation an indigenous aircraft.

Until now. With the MRJ, which will be delivered from 2017 on, Japan is trying to grab a share of the market for medium-sized regional jets. This makes the MRJ a player competing in a league with Embraer’s E-Jets, Bombardier’s Canadair Regional Jets, and Sukhoi’s Superjet 100. Its manufacturer, Mitsubishi Aircraft Corporation, a joint venture of Mitsubishi Heavy Industries, Toyota, Sumitomo and Mitsui, will be offering two variants of the jet: The MRJ90, which will hit the market first, can accommodate up to 90 passengers, depending on its configuration, whereas the smaller MRJ70 will seat around 70 people. Taken together, the two versions have so far notched up 223 firm orders and an additional 192 options.

The date of the MRJ’s first flight marks a red letter day not only for Japan, but also for MTU. The jet is powered by the PW1200G, a member of Pratt & Whitney’s PurePower geared turbofan (GTF) engine family. These propulsion systems have been selected for another four aircraft programs, alongside the MRJ, in most cases as the exclusive engine choice: the Airbus A320neo, the CSeries, the second generation of Embraer’s E-Jets, and Russian airframer Irkut’s MC-21.

“Along with the V2500, the geared turbofans are the most important engines in our order backlog,” says MTU’s Chief Program Officer Michael Schreyögg. “This definitely makes the PW1000G engines a driver of growth for MTU.” MTU’s program share in the PW1200G for the Mitsubishi Regional Jet is 15 percent. The company develops and manufactures the complete high-speed low-pressure turbine, the forward four stages of the high-pressure compressor, and three brush seals.

What is special about this engine family is that it incorporates geared turbofan technology. Unlike with conventional engines, the fan is no longer driven directly by the low-pressure turbine. Instead, the two components are uncoupled by a gearbox with a reduction ratio of 3:1, which allows either component to rotate at its respective optimum speed. Compared with today’s engines for single-aisle aircraft, the GTF saves up to 16 percent fuel. Moreover, this technology cuts noise footprint levels by 75 percent. “The low fuel consumption and noise emission levels are a major reason why the GTF engine family is so successful in the marketplace, that’s for sure,” says Dr. Rainer Martens, Chief Operating Officer at MTU. “We have invested heavily into the ramp-up of production and delivery of the components from MTU’s work share, but we are very well positioned to accomplish these tasks.”

As was the case with the PW1500G engine to power the CSeries, low-pressure turbine stress and thermal survey telemetry tests on the PW1200G engine for MRJ were conducted at MTU Aero Engines in Munich. “These tests serve to measure vibrations and temperatures on stationary and rotating low-pressure turbine components,” says Thomas Miller (Chief Validation Manager, TEC), explaining the objective of the tests, which are an important milestone along the way to engine certification. The telemetry tests in general are among the highly sophisticated parts of the certification program. Among the measuring devices used were strain gages attached to the defined locations on the blades and disks using a high temperature-resistant adhesive. The signals from the rotating measuring points were transmitted to the data logging unit installed in the test cell using MTU’s rear-mounted telemetry system, which was developed in-house. The first flight, which takes the MRJ out over the Pacific Ocean, lasts about two hours.

Some 90 minutes after take-off, the landing gear touches down on the runway again. The pilots slow the MRJ down and roll it back into its parking position.


November 20th, 2015