June first flight anticipated for P&W geared turbofan
With two airframe applications already secured and early test results looking “very, very good,” Pratt & Whitney’s geared turbofan (GTF) development engine appears headed for first flight in June.
Bob Saia, P&W’s vice president for next-generation product family, told AIN just before the Singapore Airshow that the GTF had “met or exceeded” pre-test performance predictions during sea-level and performance tests, which began in November. “We really are extremely pleased,” he said. “The first 130 hours of testing validated all of the operational parameters we were looking at, including performance, gearbox efficiency and the oil temperature management system.”
The GTF concept uses an advanced reduction gearbox to drive the fan at more efficient speeds and produce a claimed 12-percent cut in fuel burn compared to today’s engines. The development engine is based on a PW6000 core, with an all-new low-pressure system, and is now being reconfigured for the second half of ground testing, due to run for between 75 and 100 hours. For this part of the program, the GTF will run with its Goodrich nacelle system, complete with inlet and thrust reverser, and will undergo validation for flight-testing aboard P&W’s Boeing 747 flying testbed.
Early testing has revealed that engine oil temperatures were lower than predicted, leading to the only significant modifications necessary to date–a reduction in the size of the heat exchangers and a resulting small weight saving. “We realize we’re under the magnifying glass here,” said Saia. “So far it looks as if we’ll be within a percent or so of fuel-burn predictions. We’re better than 12 percent today, and we’re on plan for 20dB reduction in noise–that’s half what today’s engines produce.”
Meanwhile, development of the core engine that will replace the PW6000 in the production engine continues. Initial tests of the all-new high-pressure compressor being developed by Germany’s MTU ended in October, while the two-stage high-pressure turbine continues to undergo trials at Pratt & Whitney Canada’s Montreal facility. “We’re very pleased with the results to date,” said Saia.
P&W has stepped up its sales campaign following its success last year in securing positions aboard the Mitsubishi Regional Jet (MRJ) and Bombardier C Series airliner. “We’ve visited more than 60 airlines since October,” said Saia, “some along with Bombardier and Mitsubishi.” Mitsubishi has set a target of mid-2008 for the MRJ’s official launch. “We’re supporting a 2013 entry into service,” he added. Bombardier still awaits board approval for a launch around the same time, although some sources indicate that may slip.
While Saia insists P&W’s prime focus remains on meeting the requirements of its GTF launch customers, the big payoff would come with contracts to power replacements for the current generation of Airbus and Boeing narrowbodies. In recent months both airframers have backed away from projected 2015 launches of next-generation aircraft to follow the Airbus A320 and Boeing 737 series. The two now appear committed to a 2017-2020 time frame, giving the engine manufacturers plenty of time to develop suitable powerplants.
P&W remains the only one of the three big engine manufacturers committed to the geared turbofan concept and has fine-tuned its strategy to reflect the task of convincing the airlines it is the best way to go. For example, the design includes “product-relevant” components to ensure that it is as representative as possible of the final product. “We want to demonstrate to the airlines the simplicity of the GTF architecture, which is designed to be as accessible as possible for ease of maintenance,” said Saia. “We’re chasing a 40-percent reduction in maintenance costs for this engine.
“We’re just at the beginning of evaluating what this architecture can bring,” he added. “We believe we have a good advantage with the geared concept and we have a technology plan that carries us out to 2020 and beyond. The trend in the engine industry has been to achieve a one-percent fuel-burn improvement every year. We intend to create the same trend with geared architecture and have a thorough plan to do this. We may not know when Airbus and Boeing will go, but we’ll stay ahead of them.”