Federal officials said Thursday they are investigating an unusual rolling motion on a Southwest Airlines Boeing 737 Max 8 that may have been caused by a damaged backup power control unit.
The Federal Aviation Administration said it is working with Boeing and the National Transportation Safety Board to investigate the incident on a May 25 flight from Phoenix to Oakland. Southwest says it is working with the FAA and Boeing.
The FAA said the plane went into a “Dutch roll,” the name given to the combination of a yawing motion when the tail slides and the plane rocks from wing tip to wing tip. It is said to mimic the movement of a Dutch ice skater. It happened when the plane was at about 32,000 feet.
The pilots are trained to recover from the state and the plane landed safely in Oakland an hour later. There were no injuries among the 175 passengers and six crew on board.
According to a preliminary FAA report, an inspection after the plane landed showed damage to a unit that provides backup power to the rudder.
CBS News aviation safety analyst Robert Sumwalt told CBS News senior transportation and national correspondent Kris Van Cleave via email that “Any uncommanded flight control movement is potentially significant. The fact that that this has caused significant damage makes this kind of a big problem.”
The FAA said no other airlines have reported similar problems, and Southwest said it has not had any similar problems with other Max planes in its fleet.
Van Kleave notes that the aircraft involved was delivered in November 2022 and has therefore been in use for just over a year.
The incident was first reported by The Aviation Herald, which said a temporary repair was made in Oakland and then the plane was “transported” to Boeing's plant in Everett, Washington for further repairs.
The latest incident comes as the 737 Max continues to come under heavy scrutiny following a door plug that shuts down on a new Alaska Airlines 737 Max 9, which led to a temporary grounding of this Max version.
