Boeing told employees on Monday that it expects a slower increase in production and deliveries of new 787 Dreamliner planes because of supplier shortages of "a few key parts."

Sam Salehpour is scheduled to testify before Congress on Wednesday. Boeing says the plane is structurally sound.

Boeing engineer Sam Salehpour said assembly flaws could cause the Boeing 787 Dreamliner to fall apart midflight. Boeing says the plane is structurally sound.

Boeing is set to slow production of its twin-aisle 787 Dreamliner jets. Shares are unaffected. Investors appear to be giving the company a pass since it isn’t a quality problem—and because they hear from Boeing Wednesday morning when it reports first-quarter earnings.

On the eve of his testimony before a congressional committee, Sam Salehpour, a Boeing engineer, tells NBC News' Tom Costello that he raised concerns to his superiors about a number of issues, including a gap between parts of the 787's fuselage that is not up to Boeing's specs.

Boeing Co. said it will slow production of the 787 Dreamliner commercial jet it builds in North Charleston due to a shortage of parts for the wide-body plane.