A Southwest Boeing 737 Max underwent a serious Dutch roll and is currently out of service for two weeks

Boeing 737 max Dutch role: A Boeing 737 Max has been out of service for 20 days while authorities investigate an in-flight incident.

On May 25, a Southwest Airlines flight from Phoenix to Oakland experienced an unusual but potentially dangerous malfunction.

According to the Federal Aviation Administration incident report filed Wednesday, the plane “experienced a Dutch roll.”

Boeing 737 max Dutch roll at 32,000 feet

A Dutch roll describes an aircraft rolling from side to side, adjusting its yaw (the direction the nose is pointing) as it forms a horizontal figure-eight pattern.

Boeing 737 max Dutch roll

It can be especially uncomfortable for passengers, and Dutch roll has been used in incidents where pilots were unable to regain control of the aircraft. Pilots are trained to counteract this, and modern aircraft are fitted with yaw dampers to help prevent this.

Fortunately, the pilots regained control of the 737 Max during the Southwest incident. The FAA report also noted that the post-flight inspection discovered damage to the backup PCU (power control unit), which controls the rudder. No injuries were recorded.

FlightAware data shows that the plane, which is less than two years old, remained in Oakland for 12 days after the incident. It was then transported to Everett, Washington, where Southwest has a maintenance facility.

The FAA is investigating the reason for the event.

It’s a less-than-ideal situation for Boeing, which is dealing with a crisis following the Alaska Airlines 737 Max crash in January. The Max is under increased surveillance because it was involved in two crashes in 2018 and 2019, which killed a total of 346 people.

When asked for comment, Boeing referred Business Insider to Southwest Airlines. Southwest did not immediately respond to a request for comment sent after business hours in the US.

Boeing 737 max Dutch roll