The first Airbus A321neo powered by Pratt & Whitney engines completed its maiden flight Wednesday, marking the PW1135G turbofan’s entry into flight test on Airbus’s largest narrowbody. The six-hour mission came after delivery delays prompted Airbus to first fly the CFM Leap-1A-powered A321neo last month. Despite the switch in first flight sequence, Airbus still plans to deliver the Pratt-powered A321neo ahead of the Leap-powered version by the end of the year.

Now flying in service for Lufthansa, the Pratt & Whitney-powered A320neo became the subject of some controversy after Qatar Airways opted to surrender its position as launch customer due to operational limitations associated with engine re-start times. Airbus then had to delay first delivery to Lufthansa by three weeks due to documentation problems. In fact, more than one hiccup involving the PW1100Gs during the course of the flight-test program forced Airbus to juggle certification work among its test articles to recoup time lost on the first aircraft, grounded last April by a defect in one of the engines and again in September by a separate problem the companies described as “minor.”

Airbus has since acknowledged that it needed to shift more deliveries of Pratt-powered A320s to the second half of this year to accommodate Pratt & Whitney. During last month's Singapore Airshow, Pratt & Whitney reported that it would deliver revised engines for Airbus A320 starting in June. 

“Quite honestly, what we are incorporating are some very minor changes in the number three and number four damper in the engine, and its machining," said Pratt & Whitney president of commercial engines Greg Gernhardt during an air show press conference. "We are changing the dimension by eight thousandths of an inch. It’s a very simple change. We are tweaking the software in the engine just to optimize the start times...It’s not an issue.”