Boeing, embattled by its ongoing 737 Max airplane crisis, is the subject of a federal investigation for safety problems in the production of its fastest-selling airplane, according to The Wall Street Journal. Federal air safety regulars and Justice Department prosecutors have been probing the dangerous practices on Boeing’s 737 Max assembly line, building on a federal investigation focused on the faulty manufacturing of the jetliners and the company’s business relationship with the Federal Aviation Administration, the Journal reported. Investigators have specifically scrutinized factory issues after Boeing inspectors found debris in roughly half of 737 Max jets since last November, indicating a larger pattern of safety failures, according to the Journal. The Federal Aviation Administration, which oversees the aircraft manufacturer, is reportedly weighing a multimillion-dollar fine against Boeing for the safety issues, as well as ramping up inspections of the company’s production practices.