Pratt & Whitney has extended the preliminary design phase of its PW1000G GTF geared turbofans for the Bombardier CSeries and Mitsubishi MRJ regional jet to the middle of 2009 to give it more time to work with the two airframers before committing to the detail design of the engine.

"We initially had provisioned to start detail design on the engines as early as the beginning of this year, but we now plan to start around mid-2009," says P&W vice-president next generation product family Bob Saia.

"In the preliminary design phase we still have the ability to adjust the engine architecture as a function of airframe requirements," he says. "By mid-August we'll have all of the detailed requirements frozen from an engine perspective for both airframes. Then we'll go into our detail design phase."

Bombardier completed its key supplier selection for the CSeries in the third quarter of last year and P&W has been engaging in workshops with the chosen parties in preparation for the start of detail design.

However, with both the CSeries and the MRJ having been struggling to secure additional customers, more time is being allowed for the airframe programmes to be defined before starting detail design of the engine. "We want to ensure we don't have to go back and do any redesign. So we decided to use up some of the margin we had, which still allows us to meet the timetable," Saia says.

Bombardier's slow progress in completing order negotiations with CSeries customers since the programme's launch in July last year and the similarly sluggish sales of Mitsubishi's MRJ have not dampened P&W's GTF development plan, says Saia. "Customers are going to come - they're close to firming up [the orders]," he says. We're confident the programmes are going to go. P&W has over 1,000 engineers doing engineering work on their requirements."

The PW1000G is initially being developed with two fan diameters to match the thrust requirements of the MRJ and CSeries, the 17,000lb-thrust (76kN) PW217G and 24,000lb-thrust PW1524G and, respectively. The first engine will begin testing in mid-2010, with certification due in late 2011.

"The MRJ is due to fly in late 2011, followed by the CSeries in early 2012," says Saia. "Service entry [for both airframe/engines] is scheduled for the end of 2013."

Source: Flight International