Boeing Door Plug Removal Footage Was Overwritten, Says Safety Agency

Boeing's video footage showing exactly who worked on the 737 Max 9 door that flew off an Alaska Airlines flight has been erased, and the NTSB believes the company's trying to hide the information.

National Transportation Safety Board chairman, Jennifer Homendy, wrote a letter Wednesday to the Senate Commerce Committee ... saying they're still in the dark about which Boeing employees were involved in the door's repair. They had requested the list of names when the preliminary report into the investigation revealed the door had no bolts during the mid-flight scare on January 5.

Homendy accused Boeing of obstructing their investigation ... telling Senators Maria Cantwell and Ted Cruz, "We still have no clue who did the work to open, reinstall, and close the door plug on the accident aircraft." She added, "Boeing has informed us that they are unable to find the records documenting this work."

During her testimony before the SCC earlier this month, Homendy clarified Boeing only provided a list of employees who report to the door crew manager, but not exactly who had worked on the door plug in question.

In her letter, Homendy says she then reached out to Boeing CEO Dave Calhoun to obtain the names, but he informed her he couldn't provide that info, maintaining Boeing had no records of the work being done.

Homendy says the absence of those names has resulted in a frustrating roadblock in the NTSB's investigation -- and she clarifies they're not seeking the names for punitive reasons, and will safeguard the identities of the employees involved.

You'll remember ... the Boeing aircraft had to make an emergency landing in Portland after one of the cabin windows blew out, causing a terrifying scene with belongings of frightened passengers being sucked out.

Alaska Airlines CEO Ben Minicucci announced at the time the company would be grounding its fleet of 65 Boeing 737-9 aircraft temporarily for a thorough inspection and maintenance as a precautionary measure. By the end of the month, they got the all-clear to resume flights.

However, former Boeing quality manager John Barnett came on "TMZ Live" to make it clear he disagreed with that decision ... because he claimed Boeing was ignoring significant safety concerns.

Barnett had even taken his fight against Boeing a step further by filing a lawsuit, alleging retaliation for his whistleblowing efforts. He sat for a deposition in the cast last week, and the very next day he was found dead ... allegedly by suicide.