New engine family planned with 2007 certification target

Honeywell plans to start testing a next-generation engine family demonstrator in the first quarter of 2004 based on the multipurpose core (MPC) which ran for the first time in November 2000.

The family, formerly the F-X but now dubbed the AS903, AS904 and AS905, will succeed the TFE731 in the 4,000-6,500lb-thrust (18-29kN) class. The engine will incorporate advanced materials, and a low-inertia compressor and turbine configuration to allow use of an electric starter - a major step towards the all-electric powerplant.

The engine is due for US Federal Aviation Administration certification in 2007, making it available for new business aircraft, re-engining programmes and unmanned air vehicles (UAV) entering service later this decade. These are believed to include a next generation Cessna Citation, a successor to Bombardier's Learjet family and at least one European UAV project. "The whole programme is timed to the market needs and could be accelerated," says Honeywell Engines and Systems vice-president engineering Peg Bilson, who adds that recent MPC tests have proved the core meets or exceeds design goals.

Compared to the TFE731-60 benchmark, these include 30% lower oxides of nitrogen emission levels, higher turbine inlet temperature margins and core efficiency levels. Other targets include a hot section inspection interval of 3,500h and a core section inspection at 7,000h.

Honeywell is working on preliminary low-pressure systems for "military and commercial applications, driving to an engine demonstration in 2004". The new engine will combine the architecture of the TFE731 with technology from the AS907. It will feature integrally bladed discs, dual alloy hubs (not on the AS907) and a "split" compressor that will not require variable inlet guide vanes.

"The rebalanced low-pressure and high-pressure system will have lower inertia, which allows us to use an electric starter," adds Bilson. The engine will have a geared wide chord fan, a single axi-centrifical and two axial compressor stages, as well as a single high pressure and two low-pressure turbine stages. 

Meanwhile, deliveries of production AS907s, which received FAA certification on 25 June, have begun to Bombardier for installation on the Continental business jet.

Source: Flight International