"It's pretty obvious that this airplane is not reliable and does not have mature systems," Airbus sales chief John Leahy told reporters at a ceremony to mark the 1,000th delivery of the company's A330 plane, to Hong Kong airline Cathay Pacific.
"You can keep it flying but it's going to cost you a lot of maintenance," Leahy said, in the first comments by Airbus management about the Dreamliner's difficulties.
"What they've got is an architecture that is not mature and that will eventually become mature. It's going to take a lot of time, a lot of money, a lot of cancelled flights. And maybe redesign quite a few systems onboard."
Boeing's 787 Dreamliner has suffered from a string of problems this year, including a fire on board an empty Ethiopian Airlines plane at London's Heathrow airport last week.
British authorities said a distress beacon was the likely cause of the fire and recommended they be disabled onboard all Dreamliners.
The Dreamliner, which makes extensive use of lighter, carbon-based composite materials that reduce fuel consumption, came into service in September 2011.
But Boeing issued a global grounding order in January after lithium-ion batteries overheated on two different jets.
The US aviation giant has not been able to identify the root cause of the earlier problems, much to its embarrassment, but it said its modifications would prevent the problems recurring.
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However, the planes have been dogged by problems since they began flying once again in April, with a series of flights worldwide cancelled or diverted due to mechanical issues.
The latest incident came , when a Japan Airlines 787 that left Boston for Tokyo turned back due to a possible pump problem.