Pratt & Whitney has revealed a new slip to first flight for the geared turbofan-powered Irkut MS-21, but there is no explanation.

Although entry into service previously slid one year to 2017, the Russian programme had maintained the schedule for first flight in 2014. Irkut president Alexey Federov told reporters at the Singapore air show that the first flight should occur in late-2014 in February.

But P&W's press release today, which announced reaching a definitive agreement with Irkut on the MS-21 engine, casually revised the first flight date.

"First flight of the PurePower PW1400G engined aircraft [is] planned for 2015 and entry into service in 2017," P&W says in the release.

Asked about the apparent schedule change, P&W responded that the first flight date is accurate and that the company is planning to start testing the first PW1400G engine on the ground in 2014.

Irkut had selected the PW1400G two years ago, but finally signed a definitive agreement to offer the engine on the MS-21 family of aircraft today.

P&W's release also added new details to the MS-21 engine size and overall supply chain.

P&W's sales brochure for the PW1400G lists the power range between 125kN (28,000lb-thrust) for the 150-seat MS-21-200 and 138kN for the 181-seat MS-21-300. Irkut is also planning to offer the 210-seat MS-21-400.

But P&W's press release lists the thrust actual range for the MS-21 family between 110kN and 142kN.

In another new detail, P&W says the engine nacelle for the MS-21 will be supplied by Bombardier's Belfast-based Shorts Brothers subsidiary.

Short Brothers has previously supplied nacelles for the International Aero Engines (IAE) V2500 and General Electric CF34 turbofans, but it's the first time the company has been selected for the geared turbofan application.

Short Brothers parent company selected Goodrich to supply the nacelles for the PW1200-powered CSeries family.

Irkut has planned to complete the final design phase of the MS-21 before 1 January. The aircraft is being designed to compete in a suddenly crowded narrowbody sector, with the Airbus A320neo, Boeing 737Max, Bombardier CSeries and Comac C919 also vying for the same orders.

Irkut has estimated that total sales for the MS-21 could be around 1,200 aircraft, including one-third of that total from Russian and Commonwealth of Independent States countries.

Source: Air Transport Intelligence news