On a Southwest Airlines flight in late May, a strange rolling motion occurred on a Boeing 737 Max 8. The incident is now under investigation by the United States federal authorities on possible damage to the aircraft's backup power-control unit.

The flight in question was from Phoenix to Oakland on May 25. The Federal Aviation Administration (FAA) and the National Transportation Safety Board (NTSB) are investigating it. Southwest Airlines said it is also working with Boeing and the authorities.

'Dutch Roll'

In a report by CBS News, the FAA said the aircraft did a "Dutch roll" during the flight, which is a yawing motion caused by the tail sliding and the rocking of the wings from tip to tip. This maneuver is meant to resemble the style of a Dutch ice skater.

NTSB said on Friday, June 14, that the incident occurred around 34,000 feet.

About an hour after takeoff, the jet touched down safely in Oakland, thanks to the well-trained pilots. No injuries were recorded among the 175 passengers and six staff members on board.

The Aviation Herald reported this week that the airplane had been on the ground in Oakland until June 6 before being transferred to a repair facility in Everett, Washington. Six days later, the plane is still in Everett.

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Ongoing Investigation

The NTSB has access to information from the flight's Cockpit Data Recorder. However, the Cockpit Voice Recorder was overwritten and had a 2-hour recording time limit. The agency claims it was not contacted until June 7, two weeks after the occurrence.

Initial findings from an FAA investigation indicate that the plane's backup power unit for the rudder was damaged during the post-landing examination. Aviation safety expert Robert Sumwalt said this is a major issue since it caused substantial damage.

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