Spokesman Marc Duchesne confirmed the details reported in a UBS research note that cited meetings with chief executive Pierre Beaudoin and senior investor relations director Shirley Chenier.

The engine has been disassembled, Pratt & Whitney said on Friday, adding that after an in-depth review, "we understand the issue and have developed a plan with Bombardier to resume ground and flight testing."

Bombardier downplayed the impact of the engine failure to the test schedule of the $4.4 billion jetliner program. Its shares, which fell after the incident last week, rose more than 2.4 percent on Friday to C$3.82.

Throughout the week, there had been cautious optimism within the industry and among analysts that the fallout from the incident would be limited.

"Preliminary findings indicate that the engine failure is not related to the engine's gearbox. The engine that experienced the failure last week had had problems in the weeks prior to the incident and it had been repaired here in Mirabel," Duchesne said.

"It seemed OK and ready to fly and it did, and then there was the incident."

The failure took place during stationary maintenance testing of the CSeries, which Montreal-based Bombardier is hoping will compete with smaller narrow-body jets made by Boeing Co and Airbus.

"Bombardier ... suggested that a manufacturing defect, rather than a design flaw, may have been the cause," UBS analyst, Darryl Genovesi, wrote in his client note late on Thursday, adding that a root cause was expected to be identified by the end of the week.

Duchesne did not expect to have further details on Friday.

The May 29 engine failure initially sparked fears of further delays for Bombardier's CSeries program, already 18 to 24 months behind schedule, and sent Bombardier's shares down 3.7 percent last Friday. The plane is due to enter service in the second half of next year.

The latest details support comments made on Thursday by Greg Hayes, chief financial officer of Pratt & Whitney's parent, United Technologies Corp. He said the failure did not relate to the engine's signature gearing system, known as the Geared Turbofan.

A problem with the gearbox would have had broader repercussions because it is a component used not only on the CSeries but also on other aircraft such as Airbus' forthcoming A320neo.

Asked about the low-pressure turbine, located at the rear of the engine, Pratt & Whitney spokesman Jay DeFrank declined on Friday to elaborate on the technical details of the incident beyond confirming that the gear system was not involved.

(Reporting by Solarina Ho in Toronto and additional reporting by Lewis Krauskopf in New York; Editing by Andrew Hay and Mohammad Zargham)

By Solarina Ho and Lewis Krauskopf

Stocks treated in this article : United Technologies Corporation, Bombardier, Inc.