There are signs that the combined efforts of General Electric and AlliedSignal Aerospace - two world leaders - to produce a new business-jet engine is paying off. Graham Warwick assesses the partnership and its offspring, the CFE738 turbofan, now being tested on the Dassault Falcon 2000. Cutaway drawing by John Marsden.

When General Electric and AlliedSignal Aerospace joined forces to develop a new engine for business jets, they recognised each other's strengths. GE is half of the most successful aero-engine joint-venture ever, CFM International, and AlliedSignal's Garrett TFE731 powers more business jets than any other small turbofan.

It is hardly surprising, then, that CFE, the GE/AlliedSignal joint-venture company, is modelled on CFM International, or that its product, the CFE738 turbofan, will be assembled and delivered to customers by the same people who build the successful TFE731.

When two world leaders join forces, the result should be a world-class engine. Early indications from flight tests of Dassault Aviation's Falcon 2000 business jet suggest that the CFE738 is well on the way to realising the potential of its distinguished parentage.

CFE is a 50:50 partnership between GE Aircraft Engines of Lynn, Massachusetts, and AlliedSignal Propulsion Engines of Phoenix, Arizona. GE supplies the core and controls. AlliedSignal supplies the fan, low-pressure turbine, accessory gearbox and installation interfaces. Major subcontractors include Hispano Suiza (accessory gearbox), European Gas Turbines (compressor and rotor hardware), AlliedSignal Controls and Accessories (controls) and Israel Aircraft Industries (IAI), providing the exhaust mixer and centrebody.

CFE was formed in 1987, one of two joint ventures established by GE to exploit the GE27 core developed for the US Army's modern-technology demonstrator engine (MTDE) programme. A development of the GE27 forms the core of both the CFE738 and the GLC38 commercial turboshaft/turboprop engine. While GE's partnership with Textron Lycoming to pursue the GLC38 has yet to produce an engine, the CFE venture is close to certificating the CFE738.

The CFE738 was conceived as an engine to power a new class of mid-sized business jets. The design objective was to produce a simple, durable engine with a high thrust-to-weight ratio, low specific fuel-consumption (SFC) and affordable operating costs. The resulting engine has a bypass ratio of 5.4:1 and an overall pressure ratio of 32:1.

The initial CFE738-1 version will be certificated at 26.7kN (6,000lb)-thrust, with an automatic-power-reserve (APR) rating of 29.5kN. Installed in its first application, Dassault's Falcon 2000, the engine is flat-rated to 25.5kN to 30 degrees C (ISA +15 degrees C), with APR extending that rating to 38oC. Flat-rating will ensure a low cost of ownership, says CFE director of marketing George Purpura.

"The CFE738 is making its performance," says Purpura. "Thrust versus N[fan speed] is several per cent better that predicted and SFC is meeting Dassault's demanding specifications," he says. The SFC target is 10.4mg/Ns (0.369lb/h/lb) at take-off power, and 18.7mg/Ns in the cruise at 40,000ft (12,200m) and Mach 0.8. "That's equivalent to the CFM56 and CF6," Purpura says.

TESTING PROGRAMME

Testing of the CFE738 began in 1990. Nine engines were...