Pratt & Whitney debuts geared fan technology

Pratt & Whitney is launching an advanced technology demonstration program to bring a geared turbo fan engine to the regional and business jet market that, they claim, will offer superior performance and economics while setting new noise and emissions standards.

The Advanced Technology Fan Integrator (ATFI) combines the work and expertise of Pratt & Whitney Canada with the advanced engine staff of United States-based Pratt & Whitney and its Large Commercial Engines business. This group has been developing geared-fan system technology for more than 10 years. A 12,000-pound thrust ATFI demonstrator will run in the first quarter of 2001 with the first flight on a flying test bed later in the year. After evaluation of the demonstration project, a new family of geared turbo fans in the 10,000-to 19,000-pound thrust range could be available within 36 months from a formal program launch.

The concept of a geared turbo fan is relatively simple. A reduction gearbox between the engine’s turbine and its fan reduces the speed at which the fan turns while allowing the turbine to remain at high speed. In this way the turbine maintains its full efficiency while the fan turns at its slower optimum speed. The fan, which provides most of the thrust in a modern jet engine, retains maximum efficiency with very low noise levels. All this results in an engine that needs fewer turbine and compressor stages, meaning fewer parts.

Pratt & Whitney has been working on key fan drive gear system technologies since the late 1980s and has spent several hundred million dollars to develop systems that are extremely efficient, rugged and reliable. For instance, two different full-size 32,000 shaft horsepower gear systems have had more than 1,000 hours of durability testing. They have shown 99 percent efficiency through bearing, gear and lubrication system design innovations. These gearboxes have also shown that they can run for as much as 30,000 flight hours between overhauls. Much of this work has been done in close cooperation with partner companies Fiat and MTU.

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