Guy Norris/LOS ANGELES
Pratt & Whitney Canada plans to certificate its PT6C-67A turboshaft in mid-2000 for the Bell Boeing 609 civil tilt-rotor, first deliveries of which are scheduled for 2001.
"The main differences between this engine and other PT6 series will be in the oil system and in stopping and starting in the vertical mode," says P&WC chief executive David Caplan. "We have already done vertical start/stops and running at different attitudes, so we are quite confident," he adds.
P&WC plans to develop the 1,380kW (1,850shp) turboshaft engine using some of the original test data and equipment used in its bid to supply engines for the NASA/Bell XV-15 tilt-rotor demonstrator in the 1970s. "That's when we did a lot of analysis of the same sort of requirements," says marketing vice-president John Wright, who adds that the original attitude testing rig will be used to turn the engine during development tests. Dual pumps will be fitted to ensure adequate oil pressure in the vertical mode.
The "C" classification of the engine, as opposed to the turboprop PT6A or conventional turboshaft PT6B, indicates a direct drive from the power turbine, producing a much higher output speed of 30,000rpm. "We just take out some stages of the planetary gears," says Wright. Power will be transmitted to a reduction gearbox for which Bell Boeing has responsibility.
Around 32,700 PT6 engines have now been delivered, of which almost 7,000 are turboshafts, and more than 205 million operating hours have been accumulated.
P&WC has revealed further details of the 29.3kN (6,575lb)-thrust PW308A turbofan, now in development for Raytheon Aircraft's new Hawker Horizon business jet.
Key to the higher thrust of the new two-spool engine is a larger, 840mm-diameter, fan, 63mm wider than that of the PW305B powering the Hawker 1000. This will increase flow by 20% and contribute towards a 32% rise in thermodynamic thrust over the PW305B. The redesigned and scaled-up compressor is expected to produce a 30% higher mass-flow in the PW308A.
The first ship set of another PW300 family member, the PW306A, has been delivered to Israel Aircraft Industries for the start of flight testing in its Galaxy business jet.
Source: Flight International
