Dubai Airshow

SaM146 ready to power new Sukhoi Superjet

 - November 13, 2007, 4:53 AM

The PowerJet SaM146 turbofan that France’s Safran is showing in scale model form here at the Dubai Air Show (Stand W510) represents not just the application of engine subsidiary Snecma’s CFM56 experience to a regional jet-size engine but one of the most ambitious attempts yet to combine the strengths of Western and Russian aerospace technology.

The new engine offers thrust ratings from 15,400 to 17,500 pounds, selectable without modification to the engine via the full-authority digital engine control (fadec). That range bridges the gap between the two main regional jet variants of CFM partner General Electric’s CF34–the 14,000-pound CF34-8 that powers the Bombardier CRJ700/900 and Embraer 170/175, and the 18,000-20,000-pound CF34-10 used by the Embraer 190/195 and selected for China’s ARJ21.

According to PowerJet chairman and chief executive Jean-Paul Ebanga, the SaM146 could be uprated to produce more than 17,500 pounds of thrust. For now, though, the strategy is to offer a single model designed specifically for the regional jet market and capable of powering aircraft carrying anywhere between 60 and 110 passengers.

The engine configuration is similar to that of the CFM56-7B that powers current production Boeing 737s. It has a long duct nacelle for good acoustic behavior, a 48.2-inch wide chord fan and a compressor with three low-pressure and just six high-pressure stages–fewer than any other engine on the market, and, pointed out Ebanga, “fewer stages means fewer blades, which means less maintenance.”

The combustion chamber has the lowest emissions on the market, according to PowerJet, and there are just one high-pressure and three low-pressure turbine stages. Overall, the result of this lean architecture is a 20-percent reduction in the parts count.

Environmentally, the SaM146 should offer a comfortable margin over the International Civil Aviation Organization Committee on Aviation Environmental Protection’s current CAEP/4 standards, producing 50 percent less smoke and more than 30 percent less nitrogen oxide (NOx). Carbon monoxide and unburned hydrocarbon emissions should be 5 to 10 percent below the limit, depending on the rating of the engine, and noise emissions are expected to be at least 10 EPNdB below the ICAO Stage IV limits.

PowerJet plans to offer the engine as part of a package that will include associated support and services. It will directly provide customer support and maintenance for engine, nacelle and equipment, and a single customer interface for spares, documentation and training, field service and warranty administration. Snecma’s existing service center in Paris is to provide customer support, as is a second center to be set up in Rybinsk next year. Snecma and Saturn will overhaul the engines.

“In the regional market, most operators don’t have their own repair centers, so this is part of the value package,” commented Ebanga. “If a major airline like Air France wanted to do its own maintenance, that would be a subject for discussion, but power-by-the-hour is the baseline offer.”

Snecma and Russia’s NPO Saturn own PowerJet equally. Snecma is responsible for the high-pressure core, the accessory drive and the control system, and for the integration of engine and control system. Saturn is responsible for the fan, low-pressure compressor and LP turbine, as well as for final assembly and testing. The two partners are equally involved in testing, but Saturn has overall responsibility for the ground tests and Snecma for flight testing.

The first engine started ground tests in July 2006, following tests of the engine core and fan late in the previous year. Eight engines, each stripped and reassembled four times, are to be used for certification testing, logging more than 4,500 accelerated mission cycles. Another 10 compliance engines are to be used for certification of the Superjet 100, which is scheduled for the following October in time for initial deliveries to Aeroflot in November. The first two engines were delivered this August ahead of the airplane’s rollout in September.

Indoor testing of the fan at Moscow’s Central Institute for Aviation Motors (CIAM) resulted in improvements to the design to increase the flutter margin and improve the airflow. Medium-bird ingestion tests in a Snecma test cell showed lower than forecast blade deformation.

More than 1,500 parameters measured on the first three engines showed results close to the design data and demonstrated design thrust with a margin of more than 900 pounds. Chief designer Georgy Konyurkhov said the thrust margin means the engine will be able to power aircraft with up to 120 seats without further development.

Tests on the new outdoor test bed started last June and by August the engine had been installed on the flying test bed–an Ilyushin Il-76 from the LII Gromov Flight Research Institute at Moscow’s Zhukovsky air base. Initial flight tests at Zhukovsky in October are to be followed by further testing at Istres in southern France starting this month and running through March 2008. That is when certification by the European Aviation Safety Agency and Russia’s Aviaregister is planned.

For Ebanga, industrial cooperation is a key issue. “In this program we not only have to develop a new engine but also set up a new business framework between France and Russia to make that possible,” he said on the day in July when he took over as chairman and CEO. He sees PowerJet as an attempt to replicate the success of CFM and recalls that that project stalled for a year soon after getting under way in the early 1970s because of the lack of an agreement on technology between the United States and France.

“Industrial cooperation is a key issue,” he said. “In this project we not only have to develop a new engine but also set up a new business framework between France and Russia to make that possible. But when I see the success of CFM 30 years later, I think it’s worth doing. If we are fortunate enough, 20 years from now the landscape of the aerospace industry will be quite different because of what we’re doing now with Sukhoi, Snecma and Saturn.”

Renaissance in Rybinsk

The massive NPO Saturn plant in Rybinsk, northeastern Russia, has a notable aerospace heritage and, as industrial base for the PowerJet joint venture with Snecma, a promising new future.

Saturn’s current production programs include variants of the AL-31 for Sukhoi fighters and the D-30 that powers the Tu-154M, Il-76 and Il-62 airliners, as well as marine and cruise missile engines and gas turbines for power generation. The group also has seen major investment in new machines and facilities in preparation for the development and production of the Superjet 100’s SaM146.

One of them is the creation of a joint venture in Rybinsk, VolgAero, which makes parts for the SaM146 and other Saturn and Snecma engines and has also served as an organizational prototype for PowerJet. Saturn executive director Igor Yudin said the 240,000-sq ft facility will eventually employ 280 people, and 65 of the 100-plus machines will be computer controlled.

The VolgAero workshop has three production lines for rotating parts, tubes and brackets, and welded machined cases. There is also a common resource line for processes such as X-ray inspection, shot peening, sand blasting and plasma spraying, and a completely automated chemical line–the best in the world, according to executive director Jean-Jacques Boulanger–for blue-etch inspection of titanium parts and the preparation of nickel and iron alloys for welding.

Initial tests have used indoor test bench number 26, whose engineering and computational software and hardware has been upgraded to comply with international certification requirements. Two new test cells are under construction. Able to monitor 2,000 parameters simultaneously, they are the first in Russia to be equipped with FADEC. They are to be used mainly for testing production engines.

A new outdoor test bed at nearby Poluevo is used for performance, certification and acoustic testing of the complete propulsion system. Certification tests include crosswind operation, fan blade out and ice accretion, water, hailstone and bird ingestion, plus verification of acoustic parameters, emission control, prolonged cycle tests, and throttle behavior with the nacelle and reverser in takeoff conditions.