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Aviation History
2001
2001 - 1026.PDF
LEAN MANUFACTURING Building technology Lean manufacturing is making its mark in the business aviation market GRAHAM WARWICK/WASHINGTON DC GENERAL AVIATION manufacturing traditionally involves riveting thousands of pieces of metal together to produce an aircraft that, hopefully, is cheap to buy and fun to fly. But manufacturers and customers have become more sophisticated. From light weight piston singles to heavyweight business jets, new designs are setting new standards in price and performance, and advances in manu facturing technology are the key. Most obvious are the composite construction techniques which have allowed newcomers like Cirrus and Lancair to produce light aircraft with new levels of performance. More signifi cant are the changes being wrought in the way business jets are designed and built. Two new programmes at opposite ends of the spectrum illustrate those changes: the Eclipse 500 personal jet and Bombardier Continental super mid-size business jet. One sells for under Si million, the other for over Si5 million, but they both benefit from advances in design and manufacturing technology. Bombardier has honed its design, production and certification skills over many programmes. The result is a schedule of just 42 months from launch to delivery of the first "green" Continental - the fastest all-new aircraft pro gramme the company has ever attempted. Eclipse Aviation, by contrast, is a newcomer. The Eclipse 500 is the company's first aircraft and, while its schedule is less aggressive, the programme involves the first certification of a new manufacturing technology, friction stir welding (FSW), which will replace convention al riveting to reduce costs. Albuquerque, New Mexico-based Eclipse faces a challenge. At $837,500, the twin-turbofan Eclipse 500 is priced well below competing single-turboprop aircraft. Some of die cost difference is due to the aircraft's Williams EJ22 small turbofans. Much is due to the way it will be built. Chief executive Vern Raburn attributes the Eclipse's low cost to a "mindset". Rather than adopt the traditions of light aircraft production, die company has looked to car manufacturers for inspiration. "General aviation aircraft are built out of bits and pieces - the automotive industry hates bits and pieces," he says. As a result, Eclipse will use integrated parts. "This radically reduces parts count and assembly time." Integrated parts require extensive use of available design and modelling tools, Raburn says. "It is far more complex from an engineer ing viewpoint. It's a parametric issue: squeeze in one spot and it pops out in another." Eclipse selected Unigraphics' computer-aided design software because of its parametric capability - a change made in one area is automatically reflected throughout die design. Potentially, the biggest breakthrough in the design is the use of friction stir welding. The Eclipse 500 will be the first application of the technique to thin panels and its first use in a cer tificated aircraft. Developed by The Welding Institute in the UK, FSW is used by Boeing in production of Delta launch vehicles. COMPELLING REASON For a programme diat already combines a new airframe with a new engine, adopting a new manufacturing technology seems foolhardy. But Eclipse has compelling reasons for taking on the burden of certificating FSW. In FSW, a pin rotating at high speed is moved along the join between two pieces of aluminium alloy, creating frictional heat which softens and plasticises, but does not melt, the metal and fuses it into one piece. The fuselage pressure vessel, for example, will be three sections stir- welded together. Eclipse plans to produce a fuselage in a day, compared widi two to three days for conventional construction. "What FSW brings is efficiency in manufac turing," says Raburn. "Not only are the man- hours required reduced, but also the cycle time between operations." Both riveting and bond ing were rejected as too time-consuming and expensive. Automatic riveting was too slow and bonding required clean room conditions and lengthy cycle times. Composite construction was rejected for similar reasons. "Composites can't cook faster," he says. Pioneering a new manufacturing technology I From lightweight piston singles to heavyweight business jets, new designs are setting standards in price and performance is a major undertaking for a new, small compa ny like Eclipse. But the firm is well funded com pared with most new entrants into general aviation. "You can reduce your recurring expenses by investing in non-recurring expens es, but that requires capital," says Raburn. Opting for FSW has added cost to the pro gramme, but less than would have been involved if Eclipse had stayed with its original plan of building a composite aircraft, Raburn says. "Early in the programme we thought this would be a composite aircraft, but we conclud- edtherewasno way we could hit our production goals with the same material system as Cirrus." Cirrus and odiers use diermoset composites, whereas the automotive industry uses thermo plastics. "The cost of developing and certificat ing a thermoplastic system was easily $50 million, and if we weren't successful, there was no fallback," Raburn says. The cost of certifi cating FSW is "nowhere near $50 million" and Eclipse can fall back on conventional riveted construction, although this would increase cost. "We added effort and risk to the programme, but the risk/reward ratio was appropriate," says Raburn. Eclipse is close to deciding whether to proceed with FSW. "We have agreed the certi fication basis and demonstrated our methodol ogy. We understand the limitations of the process and it looks very positive." Parts manu- facturingmust begin in four months if Eclipse is to meet its June 2002 first flight and August 2003 certification targets. Bombardier is comfortably within the scned1- uleithassetforcertification of the Continental^ The first aircraft will roll out in April and the remaining two flight-test aircraft soon after wards. The secret, says executive vice-president engineering and product development John Holding, "is to do more workup front. It saves time and definitely saves money." The company leads the industry in using partners to share the risks and rewards of air craft development, and has refined the process for involving its suppliers in design. The Continental was the first programme to have a pre-launch joint concept definition phase. "We brought people in a lot earlier and made them part of the definition of the aircraft," says Holding. The aim was "to get it right first time" and minimise changes during design. Previously Bombardier had brought its part ners together after launch for a joint definition phase. With the Continental, the goal was to spend more time up front defining the product, "then go like hell and make it", Holding says. Most of the partners are on their third or fourth 38 FLIGHT INTERNATIONAL 27 March - 2 April 2001
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