The head of the US Transportation Department on Monday called on Boeing to co-operate with federal investigations after media reported the Department of Justice has opened an investigation into the plane maker's 737 Max 9 door plug blowout.
Federal regulators are said to have contacted some passengers and crew who were on the January 5 Alaska Airlines flight, The Wall Street Journal first reported.
The report followed testimony from the head of the National Transportation Safety Board Jennifer Homendy, who told Congress that Boeing refused to identify employees who worked on door panels on Boeing 737 aircraft.
She also said the manufacturer did not provide documentation about a repair job that included reinstalling the door panel.
Boeing said it had provided the information to the NTSB after the Senate hearing.
In a March 6 statement, Boeing said: "Early in the investigation, we provided the NTSB with names of Boeing employees, including door specialists, who we believed would have relevant information. We have now provided the full list of individuals on the 737 door team, in response to a recent request."
The company also said that regarding documentation, if the door plug removal was undocumented, there would be no documentation to share.
“We respect the independence of DOJ and NTSB doing their own work, but we're not neutral on the question of whether Boeing should fully co-operate with any entity: NTSB, us or DOJ. They should, and we expect them to,” Transportation Secretary Pete Buttigieg said.
The Justice Department has also convened a grand jury, which has the power to issue subpoenas for interviews and documents, the Post reported.
In a preliminary report, the NTSB found that the four bolts that should have prevented the panel from blowing off were apparently missing.
The NTSB and Federal Aviation Administration are also investigating other safety practices at Boeing.
The FAA audit of Boeing's 737 Max production process after the Alaska Airlines incident failed 33 of 89 tests, The New York Times reported on Monday.
The supplier, Spirit AeroSystems, the maker of fuselage parts for the 737 Max aircraft, passed six of 13 audits and failed the rest, it said.
Earlier this month, Boeing said it was in talks to reacquire Spirit AeroSystems, which it spun out in 2005, marking a shift in stance regarding outsourcing by the US plane maker.
The reintegration of Spirit into Boeing would address safety concerns, which came to a head after the Alaska Airlines' panel blowout incident.
“We believe that the reintegration of Boeing and Spirit AeroSystems' manufacturing operations would further strengthen aviation safety, improve quality and serve the interests of our customers, employees, and shareholders,” Boeing said at the time.
The 737 is Boeing's most popular aircraft. The Alaska Airlines incident is the latest issue to affect the company’s best-selling jet, which was grounded for two years, in March 2019, after a defect in its flight stabilising system was involved in two fatal crashes.
In February, the FAA gave Boeing 90 days to come up with a plan to improve quality and meet safety standards after the blowout of a door panel on one of its 737 Max planes in January.
Emirates airline president Tim Clark called for changes earlier this month at Boeing after a series of technical issues in the past couple of months brought the regulatory focus back on the US plane maker.
Dubai's Emirates, the world's biggest long-haul airline and one of Boeing's biggest customers has also said it will send its own engineers to observe the production process of Boeing's 777 aircraft and Spirit following the latest safety issues.
