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Technology update
AS900 turbofan passes first operating run
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The AS907 features a four-stage axial compressor, single-stage centrifugal compressor, two-stage high-pressure turbine, and a three-stage low-pressure turbine.
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Starting on its first attempt, AlliedSignal Aerospace's AS900 turbofan engine began operational testing. The engine, which was selected to power Bombardier Aerospace's Continental business jet, accelerated flawlessly to its governed speed. A series of test starts and accelerations was then completed, with a total operating time of approximately one hour and 45 min. Testing was conducted with dwell times at various speeds, throttle-ups, and variable inlet guide vane settings.
The AS900, a 7000-lb thrust class engine with a 34.2-in fan and a bypass ratio of 4.2, is designed with large temperature margins to meet reliability, durability, and growth expectations of business aviation and regional airlines. Its configuration features four axial compressor stages, including two variable-geometry stators, a single centrifugal compressor, an effusion-cooled combustor, a two-stage high-pressure turbine, and a three-stage low-pressure turbine driving a high-efficiency fan. The axial compressor contains integrated blade rotors for lower parts count and improved life properties. The effusion-cooled combustor provides uniform temperature profiles and reduces the output of undesirable emissions. Two lubrication sumps located in cooler engine zones provide for improved reliability and durability.
AlliedSignal Aerospace engineers began operational testing on the AS900 engine family.
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AlliedSignal Aerospace engineers designed the AS900 as an integrated powerplant system including nacelle, thrust reverser, and all engine-mounted accessories for those wishing to purchase the complete system. The engine will be offered with an on-condition maintenance program that takes place from introduction, or a fixed maintenance program consisting of mature hot-section and compressor-zone inspections at 3500 and 7000 hours, respectively.
Operational testing began 12 months after the company launched the AS900 engine family. All major engine components were evaluated prior to the construction of the complete test unit.
"The assembled test engine came together like a production engine," said Jim Kidwell, AS900 Director of Engineering, AlliedSignal Aerospace Engines & Systems. "We are running an engine core rig to validate aerodynamic and shaft dynamic predictions before taking the complete engine to full power later this month."
After additional testing, the engine will be removed from the test facility for partial teardown, inspection, and re-instrumentation. The test program will proceed toward certification in the first quarter of 2001 in accordance with the company's development plan.
Frank Bokulich
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