Southwest Airlines Co. (0L8F.L)

The FAA and NTSB are investigating an unusual rolling motion of a Southwest Airlines Boeing 737 Max

Federal officials said Thursday they are investigating an unusual rolling motion on a Southwest Airlines Boeing 737 Max that might have been caused by a damaged backup power-control unit. The Federal Aviation Administration said it was working with Boeing and the National Transportation Safety Board to investigate the May 25 incident, which happened on a flight from Phoenix to Oakland, California. According to a preliminary report by the FAA, an inspection after the plane landed showed damage to a unit that provides backup power to the rudder.