Boeing Co. said that discovery of a 787 Dreamliner manufacturing defect by wing-maker Mitsubishi Heavy Industries in Japan means 42 of the jets have to be inspected for small hairline cracks inside the wings.
None of the 787 Dreamliners involved have been delivered to airlines.
The affected wings are either on the production lines in Everett, Wash., and North Charleston, South Carolina, or still at the Mitsubishi plant in Nagoya, Japan.
In a statement, Boeing said that Mitsubishi informed it that "a change in their manufacturing process may have led to hairline cracks in a limited number of shear ties on a wing rib in the 787."
The shear ties are small composite pieces that are used to fasten the wing skin panels to the ribs that run from front to back of the wing.
According to people with knowledge of the problem, Mitsubishi found hairline cracks that were less than an inch long, all of them at a specific rib - the second rib away from where the wing root joins the fuselage.
"We are confident that the condition does not exist in the in-service fleet," Boeing said in its statement. "We understand the issue, what must be done to correct it, and are completing inspections of potentially affected airplanes."
Boeing said it will take between one and two weeks to inspect and, if necessary, fix each of the 42 airplanes.
Those inspections have already begun, and according to people with knowledge, the cracks have been found in more than one airplane at Boeing.
"There may be some delays in deliveries, but we expect no impact to 2014 delivery guidance," Boeing's statement said.
The issue was first reported Friday afternoon by the Wall Street Journal.