Pratt & Whitney expects its PW1100G engines to resume certification ground testing this week after a manufacturing defect in a 10-inch-diameter retaining ring in the combustor section resulted in the grounding of the Pratt-powered A320neo flight-test article.
Speaking Sunday at a Paris press briefing, Pratt & Whitney commercial engines president Greg Gernhardt explained that the company missed a step in the manufacturing of the part, and when the engine reaches operating temperatures the ring falls out of its retaining groove. Because the part resides in the combustor section, the fix requires that engineers “tear into the core,” said Gernhardt, a process that “does take some time.”
Pratt & Whitney has transported the two engines back to Connecticut to retrofit new retaining rings. “We have new parts available [and] we have changed the design slightly,” said Gernhardt. “We didn’t need to; we just had to go in there to make sure it was properly heat-treated, but we decided that since we had to go in there we’d put some positive retention to basically hold it in place.”
Ground testing will start with two engines unaffected by the problem and without the retrofit in place. Plans call for the retrofitted engines to arrive in Toulouse by the end of the month and resume flight testing after installation on the airplane. “It actually works out about right,” said Gernhardt. “We do about two weeks of ground testing and by the time we finish that the retrofitted engines will be available.”
