Boeing Co. said that Ted Colbert — its head of defense, space and security — would leave the company on Friday, as the beleaguered aviation giant’s new chief executive aims for big changes following a string of safety concerns and a deep slump in its financials.

Boeing's new CEO Kelly Ortberg said the company's defense unit chief Ted Colbert is leaving Boeing and that a replacement would be named later. The defense unit accounted for about 40% of Boeing's revenue in the first half of the year.