Southwest spokeswoman Brandy King said results of the reviews were handed over to the manufacturer, CFM, and did not say whether the engines were found to be safe or unsafe. King said further information would come from CFM, which did not respond to a request for comment on Saturday morning. A Southwest-operated 737 Max experienced an engine problem in late March while being ferried from Florida to California for storage. The pilots turned around for an emergency landing after reporting “a performance issue with one of the engines shortly after takeoff,” Southwest said at the time. The Federal Aviation Administration ordered the planes pulled from service last month after two fatal crashes related to a stabilization system and faulty sensor readings.Read MoreThe Wall Street Journal first reported the engine inspections.