By David Shepardson
WASHINGTON (Reuters) -The National Transportation Safety Board and Boeing (NYSE:BA) have not been able to determine who removed a door plug in a new 737 MAX 9 Alaska Airlines 737 MAX 9 that suffered an in-flight emergency in January, the board's chair said on Tuesday.
NTSB Chair Jennifer Homendy told reporters Boeing needs to make significant improvements to its safety practices.
"The safety culture needs a lot of work (at Boeing)," she said. "It is not there from the evidence itself, from what you see in the interviews. There's not a lot of trust, there's a lot of distrust within the workforce."
The Federal Aviation Administration has also said Boeing must improve its safety culture and practices and directed it to address quality issues before the agency will allow the planemaker to boost 737 MAX production.
Boeing did not immediately comment.
The NTSB has said the 737 MAX 9 was missing four key bolts. Boeing has said required documents detailing the removal of the door plug during production of a 737 MAX 9 that failed during the in-flight emergency were never created.
Boeing has provided a list of 52 prior cases of a door plug removal since 2019.
Boeing's senior vice president for quality, Elizabeth Lund, said the planemaker has now put a bright blue and yellow sign on the door plug when it arrives at the factory that says in big letters: "Do not open" and adds a redundancy "to ensure that the plug is not inadvertently opened."
Homendy said the NTSB has not been able to interview the door plug team manager, who has been on medical leave. Earlier this year, the NTSB had to press Boeing to get the names of the 25 employees who worked on the door plug.
The NTSB has conducted some interviews and obtained some written statements. "I have some concerns because each of those written statements end with the line -- I have no knowledge," Homendy said. "It's the same actual line. So I have some questions about that."