Spirit AeroSystems, which performs about 70% of the work on Boeing 737 airplanes, released a statement on Monday regarding the in-air loss of fuselage that Alaska Airlines Flight 1282 suffered on Friday.

“At Spirit AeroSystems, our primary focus is the quality and product integrity of the aircraft structures we deliver,” the statement said.

According to a Spirit spokesman, the Boeing Max 9 fuselage that came off the plane shortly into a flight from Portland, Ore., to Ontario is known as a plug. It looks like a door but generally is not meant to be opened. It’s there to meet federal requirements intended to guarantee quick exits during emergencies.

“Spirit is a committed partner with Boeing on the 737 program, and we continue to work together with them on this matter,” the company’s statement said. “Spirit is following the protocols set by the regulatory authorities that guide communication in these types of circumstances and we will share further information when appropriate.”

The company also expressed gratitude that the “crew performed the appropriate procedures to land the airplane with all passengers and crew safe.”

The Spirit spokesman said that given there’s an active investigation ongoing, the company isn’t commenting further.

According to the Spirit website, Wichita has built the Boeing 737 for more than half a century.

“In February 2018, Spirit AeroSystems celebrated the delivery of the 10,000th Boeing 737 shipset — fuselage, pylon, wing leading edges, thrust reverser and engine nacelle,” the site said.

The Max, a twin-engine plane with a narrow body, has been plagued with problems since going into service in 2017.

There were crashes involving a couple of Max 8 jets in the two years after the plane debuted, which resulted in 346 deaths.

The Max 8 and Max 9 models then were grounded for almost two years as Boeing made updates to the Max’s automated flight control system.

There have been other concerns with the Max through the years, such as manufacturing flaws, overheating related to an anti-ice system and an issue in the rudder system.

As most stocks rose Monday, Boeing’s lost 7.1% and Spirit fell 9.2%.

The Associated Press contributed to this report.