In the latest of a string of problems found on its 787 Dreamliner, The Boeing Co. (NYSE: BA) said Friday evening that Mitsubishi Heavy Industries has told Boeing that hairline cracks have been found in some parts of the wing assembly. Some 43 Dreamliners are affected, and it may take up to two weeks to make the necessary repairs, throwing Boeing’s delivery schedule out of whack.

Boeing said that the problem does not affect any of the 787s the company has already shipped. There are 123 of the planes now in service.

Mitsubishi manufactures the advanced carbon composite wing for Boeing and then ships the part to assembly plants in Washington State and South Carolina. The two factories assemble a total of 10 Dreamliners every month, and Boeing still plans to meet its 2014 forecast shipment total of 110 jetliners.

One of Boeing’s major headaches with getting the Dreamliner to market was its decision to outsource the majority of the work. About a third of that is being done in Japan, according to a report in the New York Times.

Problems with the planes’ electrical system and batteries led to a three-month grounding of the 787 fleet early last year.

Boeing shares closed Friday at $128.54, down 0.25%. They are off 5.8% this year after jumping 81.1% in 2013.

In a separate and unrelated incident, a Boeing 777-200 carrying 227 passengers and 12 crew has disappeared on a flight from Kuala Lumpur to Beijing. The aircraft vanished over the South China Sea. A Malaysian Airlines official said that the pilot sent no distress signal and that no wreckage has been seen.

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