A Boeing quality assurance inspector has come forward with serious new allegations against the airline giant shortly before its chief executive is scheduled to testify before the Senate.

Sam Mohawk has accused Boeing of systemically mishandling and losing hundreds of damaged or defective parts at its plant in Washington, likely leading to their improper and dangerous installation on 737 Max airplanes, according to a complaint filed with the Occupational Safety and Health Administration.

Mohawks report was filed last week and publicly released Tuesday by the U.S. Senate Permanent Subcommittee on Investigations, according to a statement from the subcommittees chairman, Sen. Richard Blumenthal (D-Conn.). Mohawk shared his concerns with the subcommittee last month.

The subcommittee is scheduled to question Boeing CEO Dave Calhoun on Tuesday afternoon about the companys safety practices.