Snecma Puts Silvercrest Engine To Test
Snecma has started running the first Silvercrest turbofan at its Villaroche test facility near Paris, France. With 11,000 pounds of thrust, two of the units will power the Cessna Longitude super-midsize business jet. EASA engine certification is slated for 2015 and FAA validation is expected shortly after.
“Silvercrest testing began in the last week of September,” program director Laurence Finet told AIN. The engine had left the assembly hall in the middle of the month, after which it underwent the installation and instrumentation process. During that phase, sensors record more than 900 different parameters and monitor the engine’s mechanical and thermodynamic performance.
The engine reportedly reached takeoff power in mid-October; unfortunately Snecma is revealing little updated information. Asked about a number of hours or cycles reached, business aviation marketing manager Loïc Nicolas answered, “Checking the engine’s behavior is more important than a number of hours.” Three other development engines are under construction. And a total of eight will be used for testing and certification.
One of the test articles is to fly on a Gulfstream GII, modified as a flying testbed. The first flight is pegged for mid-2013. This is “a project in the project,” Finet said. Modification work is expected to take a year-and-a-half. Pylon changes and the addition of telemetry equipment represent the bulk of the job. The GII will keep one of its original Rolls-Royce Speys.
When asked about studying a re-engining of the GII and even the GIII, as they share the same engines, Finet answered: “The Spey is rated at 12,400 pounds at takeoff; the Silvercrest could provide as much thrust at takeoff and even more than the Spey in cruise.” Although some contacts with GII and GIII owners have been encouraging, the idea is not deemed mature yet. Snecma wants to see a solid business case before moving forward, the company said.
Full-scale engine development for the Silvercrest program started in the third quarter of 2010. The core had undergone 80 hours of ground tests in 2008, after which Snecma toiled to find an application. The contract with Cessna was signed in May this year and the two companies have since started to work on installation details. The Longitude is slated to enter service in 2017.
The Silvercrest has long been rumored also to have been selected for the still-under-wraps Dassault Falcon SMS, a twinjet likely to replace the large-cabin Falcon 900. Such an application would explain the 2015 engine certification date, as the SMS is scheduled to be certified in 2016. Neither Snecma nor Dassault would comment on this.
The Silvercrest’s cold section is composed of a 42.5-in fan, a four-stage booster and a five-stage compressor (including four axial blisks and one centrifugal stage). The 20 fan blades are metallic. The “low-emission” combustor is said to have a high-altitude relight capability. It is followed by a single-stage high-pressure (HP) turbine featuring single-crystal blades and a four-stage low-pressure (LP) turbine. The HP and LP spools are contra rotating for better fuel efficiency, and the overall bypass ratio is close to 6:1.
Snecma is claiming the Silvercrest will burn 15 percent less fuel, emit 50 percent less NOx than the CAEP/6 standard and have a noise level 20 dB below Stage 4 requirements. This will halve the noise footprint “compared to existing engines in the 10,000- to 12,000-[pound-thrust] class,” said Finet, who named the two reference engines as the 9,200-pound-thrust GE CF34-3 and the 9,440-pound-thrust Rolls-Royce AE3007C2 (actually slightly below the Silvercrest thrust class).
In terms of maintenance, Snecma emphasized that the Silvercrest is a “true on-condition engine,” with no fixed interval. No hot-section inspection will be required. Another feature will be in-flight engine monitoring capability.