(Reuters) - Boeing's ( BA ) manufacturing practices, at the center of a full blown safety crisis following a Jan mid-air panel blowout, will come under scrutiny on Wednesday in two U.S. Senate hearings.

Boeing ( BA ) has been grappling with a crisis that has undermined its reputation following the Jan. 5 mid-air panel blowout on a 737 MAX single-aisle plane. It has undergone a management shakeup, U.S. regulators have put curbs on its production, and deliveries fell by half in March.

The U.S. Senate Commerce Committee is holding a hearing with members of an expert panel that released a report in February criticizing the planemaker's safety culture and calling for significant improvements.

A later session is expected to feature testimony and documents from Boeing ( BA ) whistleblower Sam Salehpour, a current engineer at the company, his lawyers said.

Salehpour has claimed that Boeing ( BA ) failed to adequately shim, or use a thin piece of material to fill tiny gaps in a manufactured product, an omission that could cause premature fatigue failure over time in some areas of the Boeing 787 Dreamliner.

Boeing ( BA ) has challenged Salehpour's claims against two of its widebody jets, the 787 and 777, which fly internationally. Boeing ( BA ) said on Monday it has not found fatigue cracks on in-service 787 jets that have gone through heavy maintenance.