Boeing Chief Executive Dennis Muilenburg was set Tuesday to begin a two-day grilling on Capitol Hill as he tries to steer the company out of crisis following two deadly crashes.

The appearance will be the first before Congress by a Boeing executive since March, when global regulators grounded the Boeing 737 MAX following the crashes which left 346 people dead.

Since then, Boeing has come under scrutiny over its development of the MAX, particularly the installation of the MCAS flight handling system that has been implicated in both the Lion Air and Ethiopian Airlines crashes.

Congressional lawmakers are expected to press Boeing on whether it cut corners to rush the MAX out to compete with an Airbus model, whether the Federal Aviation Administration delegated too much authority to Boeing during the plane's certification and whether the company has been forthcoming with regulators during the investigations.

Today's hearing in the Senate Commerce Committee falls on the first anniversary of the Lion Air crash. On Wednesday, Muilenburg was answer questions from the House Transportation Committee.

Boeing decision to strip Dennis Muilenburg of his chairmanship has raised questions about whether he will soon exit as chief executive
Boeing decision to strip Dennis Muilenburg of his chairmanship has raised questions about whether he will soon exit as chief executive AFP / Johannes EISELE

Muilenburg struck a note of humility as he entered the hearing room, saying "it's important that we remember the lives lost."

And in prepared testimony released ahead of the appearance, Muilenburg said, "we know we made mistakes and got some things wrong. We own that and we are fixing them."

Boeing is still targeting regulatory approval for the MAX in 2019. Delays in winning approval have further dented Boeing's profit outlook, on top of billions of dollars in compensation to airlines.

Senator Roger Wicker, a Mississippi Republican who chairs the Senate committee, told CNBC he intends to scrutinize Boeing's processes but said he did not see anything that would prevent the MAX from going back into service "fairly soon."

Boeing has submitted to the FAA documentation on an upgrade to the MCAS, or Maneuvering Characteristics Augmentation System, an automated system that Lion Air and Ethiopian Airlines pilots were unable to control.

"I think this plane is eminently fixable," Wicker told CNBC. "I don't think it's a hopeless cause."