Sam Salehpour

Boeing is expected to face a bruising once-over Wednesday as company critics testify at a U.S. Senate hearing, including an employee who has characterized the top-selling 787 as prone to disaster.

Federal aviation authorities are investigating claims by a Boeing engineer that the 787 Dreamliner suffers from assembly defects that threaten safety, U.S. officials have said.

Attorneys for the whistleblower, Sam Salehpour, accuse the company of putting profit over safety, and retaliating against him after he raised concerns by "involuntarily" transferring him to the 777 program.