THE BATTLE TO power the embryonic AE-100 regional jet and potential stablemates is heating up following Pratt & Whitney's decision to proceed with development of the PW6000, a turbofan in the 67-107kN (15,000-24,000lb)-thrust range.
The PW6000 emerged from the Mid-Thrust Family of Engines study and effectively succeeds a string of abortive projects with MTU, including the RTF180 and Project Blue.
P&W is "looking at Asia" for partners, and MTU has "...made a business decision" not to be a part of the PW6000, says small-engines vice-president and PW6000 project head, Tom Davenport. The move heightens speculation that MTU is working toward an alliance with German rival BMW Rolls-Royce.
For the moment, however, P&W's first major team members are Northrop Grumman and Hispano-Suiza, which signed up at Asian Aerospace '96 to design, develop and manufacture the nacelle and thrust reverser.
"It is our prime focus to work with companies and airframers," says Davenport, who adds: "You need to have an airframe." P&W's timetable calls for testing of high-pressure compressor and combustor rigs later in 1996 and a complete high-pressure spool run and full engine test in 1997. Certification could follow in late 1998 or early 1999.
Although it was late into the fray compared with BMW Rolls-Royce (with its BR715) and CFM International (with its CFM56 Lite), P&W believes that the situation gives the PW6000 an inherent advantage. "We are still in the design phase and have the opportunity to do much better," says Davenport. P&W claims that its engine is therefore more tailored to the low-cost requirements of the regional-jet market than is either of its competitors.
P&W is believed to have targeted the engine cost at around $3 million, with a core operating at a moderate overall pressure ratio (60% of the competition) and turbine-entry temperatures around 100¡C below the other engines.
The parts count is also lower, the engine having around one-third fewer blades and vanes than competing engines. In addition, P&W says that the two-shaft engine has been designed with only a single-stage high-pressure turbine stage driving a six-stage high-pressure compressor, thus reducing maintenance costs.
CFMI also unveiled new details of the CFM56 Lite, stating that "...we can do an engine in 36 months". Added to this (it is a derivative engine) CFM56 project general manager Bill Clapper says that "...neither one [of the competitors] has a base of 70 million hours to build on".
"We have nearly 70% of the engine made and tested," adds CFMI president Gerrard Laviec. "We are ready to launch." Two major versions of the engine are planned - an 82kN CFM56-7XB18 and a 98kN CFM56-7XB20. The two will be physically identical and are derived from a combination of the CFM56-5B/P and -7B engines with a cropped 1.4m fan.
BMW Rolls-Royce is supplying data on the BR700 family to all the companies involved in the various regional projects and is pushing ahead with development of the BR715. The engine is scheduled for certification in the third quarter of 1998 to power the McDonnell Douglas MD-95, while the BR710 variant recently began flights on the first Gulfstream V.
Source: Flight International
