Boeing said Friday that "hairline cracks" had been discovered in the wings of 40 787 Dreamliner jets still in production, a condition that could delay deliveries of some jets but will not alter its guidance on deliveries for 2014.
Boeing said wing-maker Mitsubishi Heavy Industries Ltd. notified it of the problem, which arose after a change in its manufacturing process.
The cracks in shear ties on wing ribs in the 787s will take one to two weeks to inspect and fix. Wing ribs run parallel to the fuselage of the plane.
"We are confident that the condition does not exist in the in-service fleet," Boeing said.
Boeing has said it expects to deliver 110 787s this year, and to earn revenue of between $87.5 billion and $90.5 billion.
The problem, the latest in a series of troubles for the Dreamliner, emerged in February. Boeing said it immediately notified customers of potential delivery delays. None of the jets potentially affected by the problem have been delivered.
So far this year, Boeing has delivered nine 787s, including one delivered Friday.
"Deliveries continue as normal outside this potentially impacted 40," Boeing spokesman Doug Alder said.