(Bloomberg) -- Federal aviation safety officials are investigating a Southwest Airlines Co. flight that experienced an unusual rolling that may be linked to a damaged backup power control unit.

The Boeing Co. 737 Max 8 aircraft landed safely and there were no injuries among the 181 people on the flight between Phoenix and Oakland, according to information from the Federal Aviation Administration. Both the agency and the National Transportation Safety Board are looking into the May 25 incident, which happened at 34,000 feet.

The plane experienced what is known as a “Dutch roll” before pilots regained control, the FAA said in a statement. Such movement involves tail “wagging” and rocking from side to side, and is named after the motion of a Dutch skating technique. An inspection after the flight revealed damage to a standby power unit and to “structural components,” the safety agencies said.

“Other airlines have not reported similar issues,” the FAA said. 

The NTSB will use information from the plane’s digital flight data recorder to determine the length and severity of the event, the agency said in a statement Friday. The cockpit voice recorder is limited to two hours of audio and was overwritten, making it unavailable.

Southwest said it’s working with both agencies on the investigation, and the NTSB said it expects to issue a preliminary report within 30 days.

Separately Friday, Bloomberg reported that a Southwest flight in April plunged to within 400 feet of the ocean off the coast of Hawaii before the flight crew pulled up and landed safely. The FAA said it’s investigating the incident.

(Updates with details from NTSB statement in fifth paragraph)

©2024 Bloomberg L.P.