The clock is ticking ever more loudly for Boeing Chief Executive Officer Dennis Muilenburg as the grounding of the 737 Max hits the seven-month mark.

The board removed him as chairman Friday after the close of the workweek, saying the change would enable Muilenburg to focus on returning Boeing Co.¡¯s best-selling jet to service. The directors expressed support for Muilenburg but pledged ¡°active oversight¡± as they handed his chairman¡¯s post to lead director David Calhoun, who has been mentioned in years past as a potential Boeing CEO.

The Friday-evening shakeup weakens Muilenburg, 55, as he tries to get the Max back in the air this quarter and prepares for a crucial appearance before Congress on Oct. 30. Boeing¡¯s reputation and finances have been battered since two Max crashes killed 346 people and prompted a global grounding, and U.S. regulators have yet to schedule a crucial test flight needed to re-certify the plane.