The Boeing Co logo is displayed outside of company offices near Los Angeles International Airport (LAX) in El Segundo, California on Jan 18, 2024.  (PHOTO / AFP)

The Federal Aviation Administration's audit of Boeing's 737 MAX production process after a panel blew off an Alaska Airlines jet in January failed 33 of 89 tests, The New York Times reported on Monday.

In the wide-ranging investigation, Boeing failed a check which dealt with the component that blew off the jet, known as a door plug, according to the presentation viewed by NYT.

Supplier Spirit AeroSystems, which makes the fuselage for the MAX, passed six of 13 audits and failed the rest, the report added.

Additionally, an audit at Spirit focusing on the door plug component found five problems and it failed the one which dealt with the installation of the component, according to the report.

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The audit raised concerns about the technicians who carried out the work and found that the company "failed to determine the knowledge necessary for the operation of its processes", according to the report.

A door plug area of an Alaska Airlines Boeing 737 Max 9 aircraft awaiting inspection is pictured with paneling removed at the airline's facilities at Seattle-Tacoma International Airport, Jan 10, 2024, in SeaTac, Washington, the US. (PHOTO / AP)

Other audits that Spirit failed included one that involved a cargo door and another that dealt with the installation of cockpit windows, it said.

Based on the FAA audit, Boeing is continuing to implement immediate changes, and is developing a plan to strengthen safety and quality, the plane maker told Reuters in an emailed statement.

The FAA and Spirit AeroSystems did not immediately reply to Reuters' requests for comment.

Earlier in the day, US Transportation Secretary Pete Buttigieg said he expects Boeing to cooperate in investigations by the Justice Department and National Transportation Safety Board into the 737 MAX 9 mid-air emergency on Jan 5.

READ MORE: Alaska jet probe: Boeing plane door plug bolts seemed missing

Meanwhile, the FAA's Michael Whitaker said the agency and Boeing hope to define the milestones the manufacturer must meet in order to increase the MAX production rate in the next 30 days.

Last week, the agency said it found "non-compliance issues in Boeing's manufacturing process control, parts handling and storage, and product control".