Southwest Airlines Boeing jet 'Dutch roll' prompts FAA investigation

Boeing 737 Max was flying from Phoenix to Oakland on May 25 when it suffered the incident

The Federal Aviation Administration has launched an investigation after a Southwest Airlines Boeing 737 Max plane experienced a "Dutch roll" motion on a May 25 flight from Phoenix to Oakland, California, causing "substantial" damage to the aircraft. 

Documentation on Boeing’s website describes a Dutch roll as when the nose of the plane "may go left to right as the airplane simultaneously banks side to side." The maneuver is caused by "wind or pilot input." 

The National Transportation Safety Board is also investigating, it said Friday.

A preliminary FAA incident report says the Southwest Airlines plane "experienced a Dutch roll, regained control and post flight inspection revealed damage to the standby PCU [power control unit]." 

There were 175 passengers and six crew members onboard the Boeing jet when the incident happened. The National Transportation Safety Board (NTSB) is also investigating, according to The Associated Press.

BOEING INVESTIGATING QUALITY ISSUE ON UNDELIVERED 787 DREAMLINER PLANES 

Southwest Airlines Boeing 737 Max 8

A Southwest Airlines Boeing 737 Max 8 airplane is seen parked at a gate at Baltimore-Washington Airport in Baltimore on April 12. (Angus Mordant/Bloomberg via Getty Images / Getty Images)

The FAA and Southwest Airlines did not immediately respond Friday to a request for comment from FOX Business. 

Boeing says on its website, "Ice skaters use the outer edge of their skates to propel themselves across the ice, rocking from side to side while also moving to the left, then to the right and back again." 

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"Airplanes can make similar lateral and directional motions in flight, rolling and yawing much like a traditional Dutch ice skater rhythmically swaying down one of Amsterdam’s frozen canals," it adds. 

"Just as skaters avoid swaying too far and losing their balance, airplanes are designed to keep roll and yaw within regulatory requirements to ensure safety — and potentially reduce the risk of airsickness," Boeing also said. 

SOUTHWEST AIRLINES CEO SAYS NO PLANS TO STEP DOWN DESPITE PRESSURE FROM ACTIVIST INVESTOR 

Southwest Airlines plane on tarmac

A Southwest Airlines Boeing 737 Max 8 airplane in Baltimore. The FAA is investigating an incident on a May 25 flight from Phoenix to Oakland, California. (Angus Mordant/Bloomberg via Getty Images / Getty Images)

The Southwest Airlines incident comes as Boeing is investigating whether some fasteners on its undelivered 787 Dreamliner planes have been incorrectly installed, the aircraft maker told FOX Business on Friday. 

A Boeing spokesperson said, "Our 787 team is checking fasteners in the side-of-body area of some undelivered 787 Dreamliner airplanes to ensure they meet our engineering specifications." 

Southwest Airlines Boeing 737 Max 8 departs from Los Angeles

A Southwest Airlines Boeing 737 Max 8 aircraft departs from Los Angeles International Airport on May 5 in Los Angeles. (Kevin Carter/Getty Images / Getty Images)

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"The in-service fleet can continue to safely operate," the spokesperson added, noting that the issue was discovered during its regular quality control checks. "We are taking the time necessary to ensure all airplanes meet our delivery standards prior to delivery. We are working closely with our customers and the FAA and keeping them updated."