Story ID: 160SnecmaSilvercrestAINNBAA2013Preprint.doc
Snecma’s Silvercrest To Power New Falcon Jet
By: Thierry Dubois
Caption: The SNECMA Silvercrest turbofan has been selected as the sole powerplant supplier for the new Dassault Falcon 5X.
Word Count: 878
French engine manufacturer Snecma has been selected as the sole powerplant supplier for the new Dassault Falcon 5X, which was unveiled earlier this week here in Las Vegas. The new Silvercrest turbofan, rated at 11,450 pounds of thrust at takeoff and with a thrust-to-weight ratio of five, is expected to be certified in 2015. It will be the culmination of a 10-year effort, as Snecma began considering designing its first business jet engine in 2005.
“We are providing Dassault with an integrated powerplant system [IPPS],” Silvercrest program general manager Laurence Finet told AIN, adding that it represents a “plug-and-play” propulsion system for Dassault. Fellow Safran group member Aircelle is supplying a long, mixed-flow nacelle for lower noise and better performance, Finet said. The thrust reverser is Aircelle’s Planar exit rear target design, which has two blocker doors that serve as the engine’s exhaust exit during flight. Also part of the IPPS are engine soft mounts to improve passenger comfort as well as part of the cabin environmental control system.
Flight-testing on a modified Gulfstream II is slated to start by year-end, after a few months of delay, and will allow testing up to 45,000 feet “unlike an airliner [testbed],” the company said. San Antonio, Texas-based Skyway Aerospace Technology (a sister company to Sierra Industries) is performing the modification.
Snecma planned to obtain a permit to fly the modified Gulfstream in the U.S., with one of its original Rolls-Royce Speys and one Silvercrest that it had hoped would be ready just before the NBAA convention. After that, the GII is to be refitted with its two Speys, and Snecma will ferry it to France, where the Silvercrest will replace one of the Speys. An extensive flight-test program will then take place at Snecma’s development center in Istres. “We don’t need flight tests for certification but we want to reassure our airframers by operating the engine in realistic operational conditions,” Finet said.
Fourth Test Article
Last month, Snecma put a fourth Silvercrest to test on the ground. Developing and certifying the engine will involve eight whole engines and one core engine.
During a visit to Snecma’s Villaroche plant near Paris in late September, the company had the second engine core in its test cell, specifically for performance testing, the first having been removed for analysis following initial tests that will allow Snecma to obtain a permit to fly. The second engine has been run to full thrust and had demonstrated “very good acceleration”–three to six seconds to full thrust. It also “starts extremely well,” said test-cell engineers, who are helping to perfect the Silvercrest’s new electric starting system.
A fifth engine core was in the process of being assembled and fitted with test instrumentation, while two others had already been dispatched to the Istres outdoor testing center in the south of France and to another test center elsewhere in France. Bird-strike and blade-out testing will ultimately be carried out at Istres, said Finet.
The certification program will essentially take place in 2014. In the same year, approximately 15 engines are to be produced.
3-D Aerodynamics
A key part of the Silvercrest design is 3-D aerodynamics. The 42.5-inch diameter wide-chord fan (which Finet admitted is “pretty large for a bizjet”) and the four-stage low-pressure (LP) compressor are driven by a four-stage LP turbine. In the high-pressure (HP) core, the compressor is made of four axial blisk stages and one centrifugal stage, to keep the engine “robust and short” and because blade-tip clearance control for axial stages that small is difficult. The HP turbine has one stage. The HP and LP spools are contrarotating for better fuel efficiency, and active clearance control is used, something that Finet described as “unique on a business jet engine.” The bypass ratio is 5.9 and overall pressure ratio is in the region of 40.
Snecma promises fuel burn will be cut by 15 percent–compared to in-service engines in the same class (for example, the GE CF34-3 or Allison AE3007)–while NOx emissions will be up to 50 percent below the CAEP 6 standard and noise will be up to 20 EPNdB lower than Stage 4.
A key differentiator, according to Finet, is Snecma’s experience in commercial engines. The ubiquitous CFM56 has logged more than a half-billion flight hours. This translates into algorithms that can interpret even weak signals for engine health prognosis. “We identify the engine’s bearing signatures, which can avoid failures,” Finet said. The Silvercrest’s new monitoring system is called ForeVision. “The engine was designed from the start as an on-condition engine,” said Finet, and with 180-minute ETOPS capability from entry into service (the aircraft’s big brother, the 7X, is a trijet so does not need ETOPS certification).
Snecma launched market studies for a 10,000-pound-thrust engine in 2005. A core demonstrator ran in 2008. Full-scale engine development began in late 2010, which AIN understands was simultaneous with the secret selection of the Silvercrest on the 5X. The first complete engine made its first run in September last year.
On the Cessna Citation Longitude, which is to enter into service in 2017, the Silvercrest will be rated at 11,000 pounds.