Allison Engine is revising growth plans for its AE3007 turbofan, to tackle the thrust requirements of the projected Embraer EMB-170, a possible stretched version of the EMB-145 now being studied by the Brazilian manufacturer.
"The growth version would use the fan from the Tay engine," says Allison large-commercial-engines vice-president Allen Novick. The engine study, recently dubbed the AE3012, has been renamed the AE30XX, to reflect the uncertainty over the final thrust requirement. "It could be 10,000lb [45kN], 11,000lb or 12,000lb," says Novick. The original 3012 study engine had an enlarged 1.2m-diameter fan to increase mass flow. Following the acquisition of Allison by Rolls-Royce, the UK manufacturer's Tay fan (which is virtually the same diameter) is now available to Allison, therefore making the development costs of the higher-thrust derivative considerably cheaper.
If Embraer opts to proceed with the EMB-170, on which a decision is due by the Paris air show in June, the Allison engine could face stiff competition from General Electric, offering a derated version of its CF34-8C1, now in development for the Canadair Regional Jet Series 700, as well as the proposed Snecma/Pratt & Whitney Canada SPW14, which is also in contention for the Aero International (Regional) AI(R) 70 project.
Allison believes that its current position as incumbent supplier for the EMB-145 gives it the advantage of commonality. Other technology advances which have been made by Allison and R-R are being considered for the AE30XX, including a recently designed high-pressure compressor.
Allison is also developing a higher-thrust, 42kN, variant of the AE3007, dubbed the A1, for a hot-and-high version of the EMB-145. The engine will develop 15% more thrust at ISA +17¹C and is due to be certificated by the end of this year. "We've achieved the higher thrust by changes in material in several stages of the hot end and with software changes in the FADEC [full-authority digital engine-control]," says Novick.
New, high-temperature, single-crystal material is being introduced into the first-stage blades and vanes and the second stage of the high-pressure turbine. The vane rows of the low-pressure turbine of the A1 will also be reset to the setting used in the AE3007H variant, which recently had its first run in the Teledyne Ryan Tier III Global Hawk unmanned air vehicle.
Allison is also offering a derated 28.5kN variant, called the AE3007A3, for the proposed 30-seat version of the Brazilian regional jet, dubbed the EMB-135.
Source: Flight International
