Boeing has discovered "hairline cracks" in the wings of 40 B787 Dreamliners currently in production.
The company said that, as a result, some 787s being manufactured in the US may now have their deliveries delayed.
It added that there is no safety risk as "the issue does not exist in the in-service fleet".
The problem came to light after Japanese wing-maker Mitsubishi Heavy Industries changed its manufacturing process and warned Boeing, in February, that this may result in hairline cracks.
Boeing said in a statement: "The affected areas are very small and the time required to address the issue will vary between one and two weeks.
"There may be some delays in deliveries, but we expect no impact to 2014 delivery guidance."
The Dreamliner has been hit by a long list of technical problems.
Among numerous issues, Japan Airlines grounded a B787 in January after engineers spotted smoke or gases believed to have come from the aircraft's main battery (see news, January 15).
Last July, Boeing asked airlines worldwide to inspect an emergency locator transmitter (ELT) following a fire on a parked Dreamliner (see news, July 29).
That move came two weeks after a UK regulator cited a battery within the beacon as the source of the blaze on an Ethiopian Airlines B787 which closed both runways at Heathrow for 90 minutes (see news, July 12).
The US Federal Aviation Administration (FAA) also issued an airworthiness directive instructing airlines to take out the ELT from Dreamliners or carry out an inspection of the devices. Boeing then advised rival manufacturers to take similar precautions.
Also in July, All Nippon Airways reported that it had found damaged battery wiring on two ELTs during safety checks and United Airlines said it had located a pinched wire on one if its B787s. The ELT battery is not the same faulty battery pack which caused all Dreamliners to be grounded from January to April.
Graham Smith
