Boeing Says Added Inspections Are Raising 737 Max Production Quality

Boeing says it has achieved significant quality improvements in the production of the 737 Max since one of the planes lost a panel in a harrowing flight in January.

The incident, on an Alaska Airlines flight, resulted in no major injuries, but it raised fresh concerns about the quality of Boeing’s planes more than five years after two fatal crashes. In response, Boeing announced changes aimed at improving quality and safety, including expanding training, simplifying plans and procedures and reducing defects from suppliers.

Speaking to reporters this week at the company’s factory in Renton, Wash., a Boeing executive, Elizabeth Lund, also provided new detail about how the 737 Max left the plant missing four critical bolts that secured the panel, known as a door plug, in place.

One of the more important changes Boeing has made since January was requiring that bodies of 737 Max planes pass a more rigorous inspection before being shipped to Renton, near Seattle, for final assembly. The body is made in Wichita, Kan., by Spirit AeroSystems, a supplier that Boeing is expected to soon acquire.

That change took effect a few months ago and has resulted in significantly fewer major defects that need to be fixed at Boeing’s factory, said Ms. Lund, the senior vice president for quality in Boeing’s commercial airplane division. The supplier inspections have also allowed Boeing to make the Max more quickly once the bodies arrive at its factory. The company is also producing fewer planes than planned because the Federal Aviation Administration limited its production rate after the January flight.

“We’ve strengthened our presence at the supplier, we ensure the parts are perfect where they ship, we inspect them there, they rework them there, and then we ship the parts,” Ms. Lund said. “The benefits have been really tremendous.”