Pratt & Whitney has incorporated design tweaks into the engines for the Irkut MC-21 that were required to fix complaints from operators of the Airbus A320neo.
The PW1400G for the MC-21 and the A320neo’s PW1100G share “nearly identical” turbomachinery. Any differences are mostly external, such as a Bombardier-designed nacelle for the MC-21 and a United Technologies Aerospace Systems nacelle for the A320neo. The MC-21 engine also drives a variable frequency generator, versus an integrated drive generator for the PW1100G, P&W says.
But the similarities in the turbomachinery led P&W to make tweaks. Qatar Airways has refused to take delivery of the A320neo because of complaints that include a 3min cool-down period required before starting each engine under certain conditions.
Immediately after an engine has been turned off, super-heated air is still trapped inside the core. If the engine is re-started too quickly, the trapped heat can lead to a slight bowing of the rotor, which leads to greater wear and tear.
At the moment, P&W requires A320neo operators to spend 3min blowing cooling air through the core before restarting each engine. The extra 6min reduces the efficiency of quick-turn operations at airports.
To reduce the cool-down period, P&W is updating the engine software and stiffening the third and fourth shaft bearings of the PW1100G engine. Those same changes are also incorporated in the PW1400G engine for the MC-21.
The US Federal Aviation Administration approved type certification for the PW1400G on 9 May.
The Russian Interstate Aviation Committee is expected to approve type certification on the MC-21 engine later this year, P&W says.
Although US businesses are still banned from doing business with certain Russian companies, the US government approved an export license for P&W to deliver the first two engines for the MC-21. Follow-on deliveries also will require an export license.
Asked if P&W has received a license to deliver additional engines, company officials replied: “We anticipate timely delivery of flight test and production engines sufficient to meet the needs of our customer.”
Irkut plans to introduce the MC-21, which could be rebranded the Yak-242 for production, next year. Another Russian company, United Engines Corp, is developing an alternative engine, the PD-14 high-bypass turbofan, for government and military customers.
