Federal officials said they are investigating an unusual rolling motion on a Southwest Airlines Boeing 737 Max that might have been caused by a damaged backup power-control unit.

The Federal Aviation Administration said it was working with Boeing and the National Transportation Safety Board to investigate the May 25 incident, which happened on a flight from Phoenix to Oakland, California.

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 wingtip to wingtip. It is said to mimic the movement of a Dutch ice skater. There were no injuries reported among the 175 passengers and six crew members.

Attorneys general across the U.S. have a new fight on their hands: protecting Americans from unproven and expensive stem cell treatments that salespeople claim can cure almost anything.

Iowa is among the states suing companies raking in millions by injecting people with stem cells that the Federal Drug Administration says have little to no benefits and can be associated with serious side effects. One expert told The Associated Press many stem cells injected into people are already dead when they are used. The FDA has issued some 30 warning letters to consumers since 2017.

Stem cells have long fascinated researchers because of their ability to reproduce and, in some cases, transform into other cell types. Because of this, they are thought to hold the potential for treating many diseases and injuries. The Iowa case is scheduled for trial next year.