NTSB conducting new interviews with Boeing on 737 MAX 9 door plug probe

Homendy said investigators are also looking at what more could be done and at the planemaker’s safety culture. She said the NTSB could conduct a safety culture survey at Boeing.

Following the incident, the FAA grounded the MAX 9 for several weeks, barred Boeing from increasing MAX production, and ordered the company to address systemic quality-control issues within 90 days after an audit found fault with the company’s manufacturing processes.

Homendy said last month investigators did not know who worked on the Alaska Boeing 737 MAX 9.

The NTSB said previously that four key bolts were missing from the door plug that blew out.

The Justice Department has opened a criminal investigation into the emergency.

Homendy in March criticised what she called Boeing’s lack of cooperation and failure to disclose some documents, including on the door plug opening and closing, as well as the names of 25 workers on the door crew in Renton. After Homendy’s comments, Boeing provided the 25 names, and the planemaker said it was cooperating.

The NTSB plans to hold a public investigative hearing into the Alaska Airlines incident on Aug 6-7.

Homendy said the hearing would include testimony from employees at Boeing and fuselage manufacturer Spirit AeroSystems and others like Alaska Airlines.