From AP:
A Boeing 737 Max suffered damage to parts of the plane’s structure after it went into a “Dutch roll” during a Southwest Airlines flight last month, U.S. investigators said Friday.
The incident happened as the jet cruised at 34,000 feet from Phoenix to Oakland, California, on May 25, but Southwest did not notify the National Transportation Safety Board about the roll or damage to the jetliner until June 7, the NTSB said. “Following the event, SWA performed maintenance on the airplane and discovered damage to structural components,” the safety board said. The NTSB comment could suggest that the incident was more serious than previously known, but aviation experts said it was too soon to know for sure.