FLUG REVUE May 2005: Engines for military trainers reviewed

May 2005

MODERN TRAINER ENGINES

By Patrick Hoeveler

These days even the military are being forced to make cuts. Thus the trend in engines for trainer aircraft is towards lower life-cycle costs. “The primary objective on the Adour 951 is to achieve the target maintenance interval of 4,000 hours,” said Andy Davis, programme manager at Rolls-Royce for the Adour, which is installed in the BAE Systems Hawk jet trainer, in an interview with FLUG REVUE. “That is a long time for an engine in a military aircraft,” he remarks apropos of the present figure of 1,250 to 2,000 hours on the predecessor, the Adour 871. The increased performance comes from improved durability of the life-cycle-limited parts, thanks to optimised materials in the hot section. Other changes on the Adour 951 are the higher thrust due to a new fan and the introduction for the first time of a digital control system rather than a hydro-mechanical one. “The FADEC system offers fault-free handling for the training environment.” And precisely this is proving enormously important on trainers. “One needs a reliable engine,” Davis explains.

For this reason, more and more manufacturers are relying on digital engine control systems (see FLUG REVUE 4/2005). A FADEC system is already in use on the PT6A-68 turboprop from Pratt & Whitney Canada for the Pilatus PC-21, allowing the engine to respond to inputs from the pilot like a jet. In addition, the turboprop engine offers lower fuel consumption and a relatively long maintenance interval of up to 4,500 hours. However, the Raytheon T-6 Texan II, also used to power the PT6A, still relies on analogue controls. The US trainer accounts for a majority of the future trainer fleets. Analysts from Forecast International predict a total of 2,238 new trainers worth $17.5 billion between now and 2013. The market for trainer engines is likely to more than double from around 100 units per year at present to almost 240 engines per year in 2013.

Among the jet engines, the Adour is the market leader. Produced jointly by Rolls-Royce (combustor, turbines) and Turbomeca (compressor), it was originally developed for the SEPECAT Jaguar fighter aircraft and over 2800 units have been built. This year production is expected to run at around 40 units, up from 15 units in 2004. “We hope that the Adour 951 production run will continue for another ten years,” says Andy Davis. The Adour 871 is still being sold, the most recent customer being India for the HAL HJT-36. The first engine is to be delivered in February 2006. Assembly will later be carried out in India. The prototype of the Hindustan trainer has been flying since March 2003 with the Larzac, formerly a competitor model of the Adour which today is supported by the joint company GRTS set up by Snecma and Turbomeca. Of the 1249 engines build up to 1989, around 780 are still in service on the Alpha Jet. No customers have yet been found for a derivative that has only 20% new parts. The Larzac 04-50 would have about 20 percent more thrust than the 04-20, at 17 kN, and possess a FADEC system.

The manufacturers see new opportunities in the Advanced European Joint Pilot Training programme, which could extend to some 150 aircraft from 2012. Here, GE is hoping to win some orders for its F414MT for the EADS Mako. The powerplant for the Super Hornet is to be modified, using control system and auxiliary equipment, to single-engined operation with reduced performance. GE already has some experience in the trainer segment: this March it delivered the first F404-GE-102 from the series for the South Korean T-50. The control system is based on the Super Hornet FADEC. A lighter titanium centre frame will save weight. Both engines have an afterburner.

Honeywell too is hoping for some major orders for the F124, which is the product of the International Turbine Engine Corporation (ITEC) collaboration with AIDC of Taiwan and powers the Aermacchi M-346 and the Aero L-159B. The F124-GA-200 for the Italian trainer is equipped with a new, two-channel FADEC from Honeywell's Modular Aerospace Control series, a family of control units that can be configured to suit a customer's particular requirements. Like most other trainer engines, it has a modular design so as to facilitate maintenance. This is true of the Progress AI-222-25 for the Yakovlev Yak-130, serial production of which is set to commence shortly. The designers are already considering versions with afterburner, higher performance and even thrust vectoring (by 20 degrees from the engine axis in every direction). But whether this will prove cost-effective on a trainer is questionable.

From page 74 of FLUG REVUE 5/2005

Last updated 14 April 2005

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