Boeing says the 737 Max—the plane that crashed late last year and this year—and 737 Next Generation have some parts that were “improperly manufactured,” according to a Federal Aviation Administration statement. CBS News reports that Boeing said the leading-edge slat track, which “modifies the lift and drag characteristics of the plane’s wing during takeoffs and landings,” is one of 148 parts from a supplier causing concerns in the 737 Max and 737 Next Generation models. The suspect parts could reportedly be “susceptible to premature failure or cracks” as a result of “improper manufacturing process.” The agency said the failure of a leading-edge slat track would not result in loss of control but could lead to “aircraft damage in flight.” Over 300 planes globally are affected by the improperly manufactured parts, and the FAA has mandated that Boeing identify and remove the parts. Boeing told CBS it has identified one batch of slat tracks that could have “potential nonconformance” issues. “We can’t change what has happened in these accidents but we can be absolutely resolute in what we’re going to do on safety going forward,” Boeing CEO Dennis Muilenburg said.