Southwest Airlines Boeing 737 Max suffers ‘significant’ damage in ‘Dutch roll’ incident

A Southwest Airlines jet was damaged during a flight last month after performing an unusual maneuver called a “Dutch roll.”

Flight 746 was en route from Phoenix to Oakland on May 25 when the incident occurred.

According to the Federal Aviation Administration, the aircraft sustained “significant” damage to the tail section as a result of the maneuver, but was able to complete the flight. The damage was not discovered until a post-flight inspection. The rudder’s standby power control unit (PCU) was damaged. The standby PCU is a backup system in case the main rudder power control unit fails. No injuries were reported as a result of the maneuver.

Tracking data from FlightAware shows that the aircraft, a Boeing 737 Max 8 with the registration N8825Q, was returned to Boeing on June 6.

Boeing referred to Southwest for comment, and Southwest referred to the FAA and the National Transportation Safety Board.

The FAA said it is working with the NTSB and Boeing to investigate the incident.

The NTSB did not immediately respond to a request for comment.

What is a Dutch Roll?

A Dutch roll is an aircraft maneuver that involves simultaneous yaw (sideways movement over a flat horizontal plane) and roll (rocking movement over a horizontal plane). It is almost always caused by a malfunction of the rudder (at the rear of the aircraft) and can often be made worse by an incorrect crew response to the onset of roll.

Dutch rolls are rare occurrences on passenger flights. The motion can stress the fuselage and cause damage, as was the case in the Southwest incident. Dutch roll incidents have caused planes to break apart in flight before.

Zach Wichter is a travel reporter for USA TODAY based in New York. Reach him at [email protected].

This article originally appeared on USA TODAY: FAA and NTSB investigate Southwest Airlines ‘Dutch Roll’ incident