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Aviation History
1987
1987 - 2233.PDF
twins. It is therefore not surprising that the company sees the PW4000 as being central to its commercial sales success over the next few years. Principal competition for the PW4000 comes from the General Electric CF6-80C2, a derivative (albeit incor porating much new technology) of the established CF6 series. The -80C2 has already been in service for a year and has todate won almost twice as many orders as the PW4000, spanning all ten possible applications. The PW4000 also faces competition from Rolls-Royce's RB.211-524, which has sold well on the Boeing 747-400 (although as yet only to the company's traditional 747 customers). Rolls-Royce also picked up the British Airways Boeing 767-300 order, but most sources do not see this as significantly threatening P & W and GE dominance on the twins. Certification of the PW4000 took place in June 1986, and covered the 56-60,0001b thrust range. The engine will be certifi cated at 62,0001b thrust next year and has, says Pratt & Whitney, the potential for growth to 65,0001b with an improved high- pressure turbine. At present, the only aircraft approaching that thrust level Pan American, and Singapore Airlines are the lead customers for PW4000-powered A310s. Left final check of a production engine before a test run. Centre maintenance check on a fan. Bottom installation of a low-pressure compressor stator requirement is the Airbus A330, which is currently looking for 64,0001b. The twin- engined MD-11 that has been mooted by McDonnell Douglas would require similar performance. Growth beyond 65,0001b thrust presents difficulties for all three engine manu facturers. Pratt & Whitney is relatively well placed, since the PW4000 core is bigger than either of those in the competing engines. But a new low- pressure system would be necessary, which the company says it could have ready by 1992 if the market so demanded. At present, it looks as if that will be unnec essary, since Airbus has yet to firm up on its A330 thrust requirement. "The A330 isn't exactly driving the market right now", says Pratt & Whitney. There is little question within the engine industry today that derivative powerplants tend to achieve higher into- service reliability. While opinions differ as to what actually constitutes a "derivative" engine, most would probably agree that it is one based on the mechanical layout of earlier models. Even in the GE and Rolls- Royce engines there have been significant mechanical changes over the years, however. But there comes a time when the hunt for greater fuel efficiency can only be satisfied with a new design. At present, the economic case for introducing a new engine seems hard to justify, with fuel prices stagnant, and with the advent of the big twins emphasising the need for higher reliability. Nobody doubts, however, that fuel prices will eventually have to rise. When that happens, fuel efficiency will once again become central to airline economics, and the industry's eyes will turn again to propulsion engineers for the answers. Pratt & Whitney campaigns the PW4000 as having "new engine tech nology with derivative engine reliability". That the engine is substantially new in terms of its mechanical design, there is no doubt. Yet many of its design features are to be seen in either the PW2037 or the JT9D. The PW4000 design stresses reliability arid reduced maintenance costs over fuel efficiency. Pratt & Whitney's targets are a 25 per cent cut in maintenance costs, and a 7 per cent reduction in fuel burn relative to the JT9D-7R4. The company has delib erately minimised emphasis on fuel burn, relying on a "product improvement programme" to further enhance fuel effi ciency in the long term. The philosophy differs somewhat from that of the PW2037, which introduced a new high speed core that exercised the company's materials technology to a higher degree than ever before in the search for increased fuel efficiency. (The PW2037 core has, in fact, been very reliable in service. Most of the PW2037's reliability problems centred on the gearbox, design FLIGHT INTERNATIONAL, 31 October 1987 31
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