Five Manufacturers Proposing 90-Seat Turboprops

By Bradley Perrett
Source: Aviation Week & Space Technology

ATR thinks it can develop its proposed aircraft in five years for $2 billion but does not expect shareholder approval this year. One of its two owners, Finmeccanica, is keen to proceed, but the other, EADS, is withholding permission, reluctant to send engineers from its busy Airbus subsidiary to help develop the aircraft. Airbus believes in the concept, however, and Finmeccanica subsidiary Alenia Aermacchi has said it will build a 90-seat turboprop without EADS, if necessary. So the prospects for a launch, whether Franco-Italian or just Italian, look very good, although the timing is less certain.

While waiting to launch a design that is ready to go, ATR is still working on refinements, because an aircraft's costs are determined early in its development, stresses Chief Executive Filippo Bagnato. Once the preliminary design is adopted, the opportunities for improvement are much more limited.

Meanwhile, Bombardier is studying a stretch version of the Q400. “We do believe the Q400 NextGen aircraft is an excellent baseline platform for a future 90-seat turboprop aircraft, as it already has the best seat-mile economics in the turboprop segment,” says a company spokeswoman. “There continues to be a strong interest for a 90-100-seat turboprop and it's an aircraft that customers are asking us about.” The engineering and financial pressures presented by the CSeries suggest that Bombardier will not move early to stretch the Q400, if ever. Notably, however, in this field only the Canadian company can derive its aircraft from a current production type.

The Q400 stretch could also have been the Korea Aerospace Industries (KAI) project, but talks with Bombardier are over or almost over, and the South Koreans, sure they need a partner, are still looking for one, says a non-Korean industry official who has discussed opportunities with them. Details of an indigenous South Korean design, the DRA, have been published by the Korea Institute of Science & Technology Evaluation and Planning. Korean Air would also take part in the program, but KAI, with its larger design office, would surely be the leader.

Ideally, the development of the DRA or an alternative will be predominantly South Korean, so the local authorities can use it to achieve FAA endorsement of their certification capabilities. If South Korea cannot partner with a current manufacturer, then it may conceivably look for a former turboprop builder to consult and another country to share in development. The project's distance from launch undermines its chances, since the market will look less attractive to KAI and any co-investor as competing programs move ahead. On the other hand, the South Korean determination to have experienced foreign help augurs for a dependable schedule.

In terms of design, there are great differences among the proposed concepts. ATR, most radically, wants to build its aircraft with a five-abreast cross section, the widest for a Western turboprop since the 98-seat Lockheed Electra and 139-seat Vickers Vanguard left production in the early 1960s. ATR has made the choice because its 70-seater, the ATR 72, which is based on the 50-seat ATR 42, cannot be stretched much further. The height of the landing gear would limit takeoff rotation too much if the ATR 72 were stretched by more than another seat row or two, so ATR could provide at most 74 or 78 seats with a derivative aircraft.

The large ATR turboprop must therefore be an all-new type and its initial passenger capacity of 90 would be that of its smallest version. Commercial aviation regulations may lead to later versions being quite a lot bigger: Airlines must employ a third cabin attendant when seating exceeds 100. Operating a one-class aircraft with 101 seats is therefore uneconomical. Efficiency returns as the seating rises beyond 101, but a four-abreast fuselage then becomes heavy, because a long and skinny tube needs heavy reinforcement. That explains why ATR is going for five-abreast seating. Moreover, a five-abreast fuselage can be stretched as far as 172 economy seats, DC-9 experience shows.

One might think Airbus would look askance at ATR laying the groundwork for an aircraft seating more than 100 passengers, and potentially a lot more than 100. But the commercial jet builder is studying the regional market and sees new and bigger turboprops as likely, says Kiran Rao, ATR chairman and Airbus executive vice president of strategy and marketing. An Airbus proposal for the concept is called NRA, presumably standing for New (or Next) Regional Aircraft, says an industry official from outside of the program. Alenia Aermacchi also has a concept design.

The design that ATR presented to its shareholders last year and is still refining is likely similar but worked out in greater detail. When it is eventually revealed, such details as the engine, wing area and landing gear height will show how far the joint company expects to stretch its aircraft without major changes. Provisions for growth well beyond 100 seats could add greatly to the production and operating cost of the first version, however, in contrast to the ATR 72's penny-pinching design. The problem appears in the Alenia Aermacchi concept, the 90-seat version of which would weigh a hefty 32.9 metric tons on takeoff, albeit also offering high speed. Penalties will be minimized if the first version of ATR's aircraft has closer to 100 seats.

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