To maintain airline safety, “that means an enormous amount of rigor in dealing with Boeing, in dealing with any regulatory issue,” Buttigieg said on Fox News Sunday. “And that’s exactly what the FAA is doing.”

Boeing has faced scrutiny from passengers and regulators after a series of high-profile flight incidents this year, most notably the blowout of a fuselage section on a brand-new 737 Max 9 during an Alaska Airlines flight in January, which has prompted a criminal investigation by the Justice Department.

Four bolts that should have prevented the panel covering an unused door from flying off were apparently missing, the National Transportation Safety Board found in a preliminary report. All 171 passengers and six crew evacuated the plane without serious injury.

“In an event like this, it’s normal for the DOJ to be conducting an investigation,” Alaska Airlines said Saturday in a statement. “We are fully cooperating and do not believe we are a target of the investigation.”

A Boeing Co. spokesperson declined to comment and the Justice Department didn’t respond to a request for comment.

Additionally, Boeing said in a letter to Congress that it can’t locate records of the work performed on the door panel that failed, an unusual acknowledgment in an industry that places a significant emphasis on documentation.

Buttigieg’s comments follow a mishap-filled week for United Airlines flights. One of its aircraft ran off a taxiway at Houston on Friday, another lost a tire after takeoff from San Francisco and a flame-spewing engine forced another into an emergency landing.

“Every time I step off of a jet bridge and onto a plane, which is every few days, I know that I am participating in the safest way to travel in the world. And we never take that for granted,” Buttigieg said.

The FAA ordered a temporary grounding of 171 planes for inspection following the Alaska Airlines blowout in January as carriers across the globe briefly took their Max 9’s out of service. In 2019, Boeing grounded its entire fleet of Max aircraft after two deadly crashes.

The accidents led to a $2.5 billion settlement with the Justice Department to resolve a criminal charge related to a conspiracy to defraud the FAA. Under that agreement, Boeing took on a compliance program designed to prevent it from deceiving regulators. It agreed to cooperate with the government for three years, after which the charge would be dismissed.

The Alaska Air incident took place two days before the agreement’s expiration.

Boeing shares have tumbled about 24% since the end of December, the most in almost two years.