A Boeing manager tried to stop the production of the company's embattled 737 Max jet over safety concerns before the first of two deadly crashes that triggered a global grounding of the narrow-body plane.
Peter DeFazio, chairman of the Transportation and Infrastructure Committee, released the allegations in a statement ahead of a hearing on Wednesday, when Boeing chief executive Dennis Muilenburg will testify in the second of two congressional hearings.
"We now know of at least one case where a Boeing manager implored the then-vice president and general manager of the 737 programme to shut down the 737 Max production line because of safety concerns, several months before the Lion Air crash in October 2018," Mr DeFazio, an Oregon Democrat, said in the statement that was released by the committee.
Mr Muilenburg faced a tough grilling by US policymakers at a hearing in Capitol Hill on Tuesday, where politicians asked what Boeing knew about the flight control system, known as MCAS, that was implicated in the two deadly crashes and why it delayed releasing internal 2016 messages that described erratic behaviour of the software in a simulator.
The two hearings are among the most high-profile congressional hearings scrutinising aviation safety in years, intensifying pressure on Mr Muilenburg who is battling to regain the confidence of airline customers and return the Max to service.
The two crashes, in Ethiopia and off the cost of Indonesia, killed 346 people and shook public trust in the jet, which is in its seventh month of ban.
On Wednesday, Mr Muilenburg will face a second congressional hearing in front of the House Transportation and Infrastructure Committee, headed by Mr DeFazio.
"Something went drastically wrong, a total of 346 people died, and we have a duty to fix it," Mr DeFazio said.
Despite the tough questions from policymakers on Tuesday, Boeing shares closed 2.4 per cent higher at $348.93 on Tuesday at market close in New York.
On Tuesday, Mr Muilenburg took a remorseful tone, admitting that "we know we made mistakes and got some things wrong. We own that, and we are fixing them".
Family members, holding photos of victims of the crash, were seated three rows behind Mr Muilenburg during his testimony.
