“Second-generation” GEnx Powers Fifth 787
The June 16 first flight of the fifth Boeing 787 Dreamliner (ZA005) also marked the first time a pair of GE Aircraft Engines' GEnx-1B turbofans powered an airplane to altitude on their own. Captains Mike Bryan and Mike Carriker flew the airplane for three hours and 48 minutes, and reported no anomalies.
“The airplane handled just like I expected,” said Bryan, who captained the flight. “It was just like every other 787 flight that I've flown in the last several months-smooth, per plan and excellent.”
Given the amount of time the more than two-year delay to the 787 gave GE to work on some earlier weaknesses, Bryan should have expected nothing less. Nevertheless, while Boeing puts ZA005 through its paces, GE continues to work on weight-saving efforts and a project to incorporate into the design a new low-pressure turbine early next year.
Originally certified in March 2008, the engine has, in fact, evolved since then. “We didn't go home and take a nap for two years,” said GEnx program manager Tom Brisken. “We've been continually working it so we really think we're on the second generation of the engine. We're going to certify all those features; we were able to take out some weight; we were able to put in better performance; we were able to improve the durability…all those things are in this vintage of engine.”
Still, Brisken didn't necessarily accept the premise that the more than two-year delay to the 787 program resulted in a net benefit to GE. “There's good and there's bad,” he said. “The bad part of it is we're spending a heck of a lot more money than we ever envisioned that we'd have to spend on this program. But it's always better to fix the problems in the factory before you go into service and learn from what you're seeing on the hardware and quickly adapting to that.”
Expected to burn 7 percent less fuel and produce 30 percent less NOx than the GE90, the GEnx is largely the product of better computational analysis tools that allowed engineers to remove airfoils from each stage of the engine. For example, the fan on the GEnx uses 18 composite blades, compared with 22 on the GE90.
Unfortunately, removing too many airfoils resulted in separated flow in the low-pressure turbine, requiring a redesign. “It was a stretch for us,” said Brisken. “We had done some component testing that led us down a path, but obviously Mother Nature didn't like what she was being given so we had to put a little bit more weight back into the low-pressure turbine.”