UPDATE 2-U.S. regulators say some Boeing 737 MAX planes may have faulty parts

The U.S. Federal Aviation Administration on Sunday disclosed a new problem involving Boeing Co's grounded 737 MAX, saying that more than 300 of that troubled plane and an older model 737 may contain improperly manufactured parts and that the agency will require these parts to be quickly replaced. The FAA said up to 148 leading edge slat tracks manufactured by a Boeing sub-tier supplier are affected and cover 179 MAX and 133 NG aircraft worldwide. In a statement issued after the FAA announcement, Boeing said it has not been informed of any in-service issues related to this batch of slat tracks.