A series of United Airlines flight mishaps, including midflight mechanical issues and a runway excursion, require deeper investigation by federal authorities, according to two Texas lawmakers.

In a letter to Transportation Secretary Pete Buttigieg sent Thursday and shared with CQ Roll Call, Republican Reps. Troy Nehls and Daniel Crenshaw point to six incidents on United Airlines flights over the past few weeks, accusing the carrier of a “culture of mismanagement” and “lack of emphasis on aviation safety.”

“[T]hese incidents occurred with a variety of different aircraft supplied by different companies in an extremely short time span. The reoccurring variable appears to be United Airlines,” they wrote. “Reports of mechanical failures and maintenance lapses have raised serious questions about the airline’s commitment to safety.”

Two of the incidents concerned flights coming in and out of George Bush International Airport in Houston, Texas — a United hub just outside of Nehls’ district. One United flight skidded off the runway into the grass while taxiing to the gate, and another outbound from the airport had to return after its engine caught fire when bubble wrap got caught in it, according to United. No crew or passengers were injured in either incident.

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“I have NO CHOICE but to use United to get back to Houston. . . . and now their planes are literally falling apart and we still can’t choose another carrier,” Crenshaw said on X responding to the runway excursion incident. “Congress should act.”

The letter cites another incident outside of Texas, in which a United plane that landed in Oregon on March 15 was discovered to be missing a panel during a post-flight inspection. But other incidents have also caused concern, including one this month in which a wheel fell off a United flight from San Francisco after takeoff, and another flight headed to that city that had to return to Sydney, Australia, due to a “hydraulics fault.”

“As the agency charged with the flying public’s safety, we implore you to take this matter seriously, reveal the results of your investigation, and apply appropriate accountability mechanisms,” they write in the letter.

The call for an investigation comes amid sharp scrutiny of aviation safety and passenger protections on Capitol Hill, including Senate oversight of Boeing’s manufacturing processes following a mid-flight door plug blowout in February.

A source familiar with Federal Aviation Administration investigations said these mishaps happen every day and the agency keeps close tabs on each one, regardless of whether they pose a safety threat or not. The source said that the current national focus on aviation safety could certainly be playing into increased scrutiny of flight incidents, but added that the FAA likely already has a team of investigators looking into the United mishaps.

United Airlines CEO Scott Kirby said in a statement that the incidents are unrelated and that the company is reviewing each case. He also announced a “centralized training curriculum” for new hire maintenance technicians and said United is dedicating more resources to supplier network management.

“I’m confident that we’ll learn the right lessons from these recent incidents and continue to run an operation that puts safety first and makes our employees and customers proud,” Kirby said.

Senate Commerce, Science and Transportation Chair Maria Cantwell, D-Wash., and ranking member Ted Cruz, R-Texas, have vowed to hold more hearings on aviation safety.

“There have been multiple accidents and near accidents, including near misses that could have easily cost hundreds of lives,” Cruz said broadly of flight mishaps in an interview last week.