Enlarge / National Transportation Safety Board Chair Jennifer Homendy testifies about the Boeing door-plug investigation before the Senate Commerce, Science, and Transportation Committee on March 6, 2024, in Washington, DC. (credit: Getty Images | Kevin Dietsch )

A government investigation into a Boeing 737 Max 9 plane’s door-plug blowout has been hampered by a lack of repair records and security camera footage, the National Transportation Safety Board’s chair told US senators. Boeing was “unable to find the records” and told the NTSB that the security camera footage was overwritten.

“To date, we still do not know who performed the work to open, reinstall, and close the door plug on the accident aircraft,” NTSB Chair Jennifer Homendy wrote Wednesday in a letter to leaders of the Senate Commerce, Science, and Transportation Committee. “Boeing has informed us that they are unable to find the records documenting this work. A verbal request was made by our investigators for security camera footage to help obtain this information; however, they were informed the footage was overwritten. The absence of those records will complicate the NTSB’s investigation moving forward.”

A Boeing spokesperson told Ars today that under the company’s standard practice, “video recordings are maintained on a rolling 30-day basis” before being overwritten. The NTSB’s preliminary report on the investigation said the airplane was delivered to Alaska Airlines on October 31, 2023, after a repair in a Boeing factory. On January 5, the plane was forced to return to Portland International Airport in Oregon when a passenger door plug blew off the aircraft during flight.