FILE - The logo for Boeing appears on a screen above a trading post on the floor of the New York Stock Exchange, July 13, 2021. Boeing says the head of its 737 jetliner program is leaving the company immediately, paving the way for the aircraft maker to appoint new leadership at the troubled division. (AP Photo/Richard Drew, File)

New York (CNN) — Boeing removed executive Ed Clark, the head of its 737 Max passenger jet program, after a dramatic – and terrifying – midair blowout in January underscored ongoing problems with the jet.

The 737 Max is Boeing’s best selling plane, but has been a source of repeated problems over the last five years, starting with a 20-month grounding in 2019 and 2020 following two crashes that killed a total of 346 people. More recently, a door plug on a Boeing 737 Max flown by Alaska Airlines blew out soon after taking off, leaving a gaping hole in the side of the plane.

A preliminary report by the National Transportation Safety Board found that the four bolts that should have held the door plug in place were missing when the plane left Boeing’s factory.

The NTSB report did not assess blame for the missing bolts and the accident but in a statement to investors before the findings were released, Boeing CEO Dave Calhoun assumed responsibility for the incident.

“We caused the problem, and we understand that,” he told investors during a call after reporting the latest quarterly loss at the company. “Whatever conclusions are reached, Boeing is accountable for what happened.”

Clark,who had been at Boeing for 18 years, had only been in charge of the Max program since March of 2021, assuming that title after the jets had been returned to service following the crashes. But he had previously held roles related to the 737 Max, including as chief engineer and chief 737 mechanic.

A 2019 aerial photo shows Boeing 737 MAX airplanes parked on the tarmac at the Boeing Factory in Renton, Washington. (Lindsey Wasson/Reuters/File via CNN Newsource)

With the news of Clark’s departure, Boeing also announced a shuffling of a number of executives in its Boeing Commercial Airplanes unit. It created a new executive position, Senior Vice President for BCA Quality, and named Elizabeth Lund to that position.

Lund had been senior vice president and general manager of airplane programs for Boeing Commercial Airplanes, overseeing not just the 737 Max but other models of passenger jets made by the company.

Mike Fleming, who had previously been senior vice president of development and customer service, will assume the role Lund previously held. And Katie Ringgold, who had been vice president of 737 Max deliveries, will assume Clark’s former position overseeing the Max.

Beyond the problems that have resulted in the grounding of the 737 Max 8 and Max 9 after the incidents, the problems at Boeing have also postponed certification of two new versions of the jet, the Max 7 and a stretched version, the Max 10.

The CEOs of three key Boeing customers – United Airlines, Southwest and Delta Air Lines – have recently all said they no longer are counting on getting those new versions of the planes they had ordered anytime soon. United CEO Scott Kirby referred to the Alaska Air incident as the “straw that broke the camel’s back” in terms of his airline’s planning assumptions for the Max 10.