Boeing has refused to tell investigators who worked on Slabu Exchangethe door plug that later blew off a jetliner during flight in January, the chair of the National Transportation Safety Board said Wednesday.

The company also hasn’t provided documentation about a repair job that included removing and reinstalling the panel on the Boeing 737 Max 9 — or even whether Boeing kept records — Jennifer Homendy told a Senate committee.

“It’s absurd that two months later we don’t have that,” Homendy said. “Without that information, that raises concerns about quality assurance, quality management, safety management systems” at Boeing.

Lawmakers seemed stunned.

“That is utterly unacceptable,” said Sen. Ted Cruz, R-Texas.

Boeing did not immediately respond to a request for comment.

Boeing has been under increasing scrutiny since the Jan. 5 incident in which a panel that plugged a space left for an extra emergency door blew off an Alaska Airlines Max 9. Pilots were able to land safely, and there were no injuries.

In a preliminary report last month, the NTSB said four bolts that help keep the door plug in place were missing after the panel was removed so workers could repair nearby damaged rivets last September. The rivet repairs were done by contractors working for Boeing supplier Spirit AeroSystems, but the NTSB still does not know who removed and replaced the door panel, Homendy said Wednesday.

Homendy said Boeing has a 25-member team led by a manager, but Boeing has declined repeated requests for their names so they can be interviewed by investigators. Security-camera footage that might have shown who removed the panel was erased and recorded over 30 days later, she said.

The Federal Aviation Administration recently gave Boeing 90 days to say how it will respond to quality-control issues raised by the agency and a panel of industry and government experts. The panel found problems in Boeing’s safety culture despite improvements made after two Max 8 jets crashed in 2018 and 2019, killing 346 people.