Boeing announced that it has discovered that about 40 of its 787 Dreamliners have hairline cracks in the wings, but notes the company will still hit its quota of 110 Dreamliners shipped in 2014.

The cracks were also found on the 787-9 models, which are currently going through flight tests, reports Reuters. Boeing stressed that the cracks were only found on planes not yet being used by airlines.

The problem seemed to stem from the wing manufacturer, Mitsubishi Heavy Industries Ltd., who changed their manufacturing process and reached out to Boeing after discovering the resulting cracks.

Boeing spokesman Doug Alder said, "We are confident that the condition does not exist in the in-service fleet."

The cracks are the result of fasteners that connect carbon fiber composite wing panels with aluminum shear ties on the wing ribs being over-tightened. The fasteners were being used without manufacturing fillers, which lead to small cracks of about one inch on the wings.

The Wall Street Journal notes that the cracks affecting so many planes show the problems that trying to quickly manufacture something could wrong.

The lighter and more fuel efficient plane has seen high demand, but also numerous problems, such as Boeing having to fix a lithium-ion battery problem, that left the company forced to suspend deliveries for a short while.

image courtesy of Wikimedia Commons