While western turboprop airliner makers edge cautiously toward new designs, India is accelerating long-anticipated plans to develop a regional transport aircraft that could help launch the next generation of large turboprop engines.

State-owned Hindustan Aeronautics Ltd. (HAL) has invited engine makers worldwide to offer data on their engines and integrated propulsion systems (IPS) for a 70-100-seat transport. The request for information (RFI) covers turbofan and turboprop options, but the thrust requirement called for is viewed by powerplant makers as the first significant potential launch window for a new, fuel-efficient family of propeller engines. The same engines could also power future designs under study by established turboprop manufacturers ATR and Bombardier.

General Electric, Pratt & Whitney Canada and Snecma have all begun new large turboprop projects in anticipation of the development of next-generation airliners to succeed the mainstream ATR 42/72 and Bombardier Dash 8 models. However, all the engine manufacturers' projects remain in preparation mode pending the firm launch of a new airframe program.

India's regional aircraft plan has been progressing slowly since it emerged in 2008, but it received a boost last July when the government gave the go-ahead to the long-delayed strategic project for the development of a broad-ranging civilian aircraft program. The plan focuses initially on the 70-100-seat range, with design and development expected to cost at least 43.55 billion rupees ($700 million) and series production an additional 32 billion rupees.

HAL has completed preliminary work and, based on the initial concept and feasibility studies, the government has proposed a special-purpose vehicle to help develop the program, with HAL and National Aerospace Laboratories as the lead agencies. “While the feasibility study has been carried out earlier to arrive at an aircraft configuration, it is envisaged that this information (from the RFI) will be important to consider [a] family of aircraft requiring a specified range of power, which can now be tailored to the engines that will be down-selected,” according to a statement from HAL.

The RFI requirement is for 10 IPS sets for prototype development and an anticipated production demand for around 1,000 engines. However, long-term plans call for supplying engines at a rate of 80 sets per year during a 20-year production run, which means the balance of engines would be provided via transfer of technology to Indian companies. HAL says prototype engines should be provided around 2017, with production units expected from 2019 onward. “Emphasis is made that all information is required not only for the engine, but also for an IPS that includes . . . optimum nacelles with powerplant (turbofan or turboprop, including propellers) and associated systems, including features for [a] thrust-reversing mechanism,” states the HAL-issued RFI.

“The aircraft will fly at a speed of 700 kilometers per hour. This is a lower speed than other aircraft, but will save a substantial amount of fuel. It will also have space to carry 1,000 kilos [2,425 lb.] of cargo,” says G. Madhavan Nair, chairman of the high-powered committee overseeing the project. “Many of the engine manufacturers came and talked to us,” he adds.

Leading contenders include GE, which is studying a new large turboprop based on the GE38 turboshaft currently in development for the U.S. Marine Corps' Sikorsky CH-53K heavy-lift helicopter. In its turboshaft form, the GE38 provides over 50% more power than the T64, which powers the CH-53, while burning 18% less fuel. Last December, GE completed a 300-hr. cyclic durability test to clear the way for the start of flight testing of the CH-53K later this year. The timetable for test and development of the military engine, which is set to enter squadron service in 2019, would also dovetail with the schedule for India's regional transport. In its commercial form, the GE study engine is dubbed the CPX38.

Pratt & Whitney Canada (P&WC), which currently dominates the large civil turboprop market with the PW100/150, is also embarked on development of a new “centerline” engine capable of up to 8,000 shp—the NGRT (Next Generation Regional Turboprop). Phase 1 of development work on NGRT was completed in 2013 and included full evaluation of a new compressor at engine maker MTU's facilities to verify performance and load limits. Additional work this year will focus on finalizing design requirements for aspects such as electrical load offtake, component sizing, engine control systems and bleed air amounts for air management. While keeping in mind prospects such as Bombardier's Q400X study and growth versions of the ATR 72, P&WC also has been tracking regional projects in China, Russia and India. Assuming the Indian program launches first, P&WC says initial ground tests will begin within 18 months of firm go-ahead, with first flight in 30 months and entry-into-service in 3.5 years.

Safran group engine-maker Snecma is similarly well into studies of large turboprops in the 5,000-shp class. According to Snecma CEO Pierre Fabre, “pressure to lower fuel consumption [by 20-30%] should also reinvigorate the turboprop segment of this market. We are considering different turboprop concepts for an engine that would provide a considerable reduction in fuel consumption.” As with GE and P&WC, the lack of a firm application has prevented a formal launch, although as early as 2012 the effort was far enough along to be assigned its own team. The provisional timetable for the concept engine, which combines Snecma turbine design know-how with compressor technology developed by sister company, Turbomeca, calls for entry-into-service in the 2018-20 timeframe.

The new aircraft has been proposed in anticipation of a boom in the Indian regional civil aviation market within a decade. Air travel in the country has been growing at a rapid rate, and forecasts indicate the trend will continue. In 2000, India had only 225 commercial aircraft, but boosted 735 by 2010. Currently, 1,187 civil aircraft are registered to scheduled and non-scheduled operators, according to aviation regulator Directorate-General of Civil Aviation. India is the ninth-largest aviation market, handling 121 million domestic and 41 million international passengers annually. The country is touted to become the third-largest civil aviation market by 2020 and because large parts of the country are still unconnected by air, there are prospects for stronger growth in the near future.

The civil aviation business in India indicates emerging requirements for 19-, 30-, 50- and 70-seat aircraft as the traffic builds on regional routes. “[HAL] has a strategy to address these requirements,” says Chairman RK Tyagi. According to the consulting agency AT Kearney, India's regional aircraft fleet will rise to 261 by 2025 from 55 in 2011 at a compound annual growth rate of 12-13%.