Boeing Finds More Concerning Quality Issues With Other Aircraft

The Jan. 5 incident on an Alaska Airlines flight when the plane's door plug blew out at 16,000 feet prompted an immediate investigation of all Boeing 737 MAX 9 aircraft in Alaska and United Airlines' fleet. But it turns out the door plug safety issues aren't the only problem.

Boeing Commercial Airplanes CEO Stan Deal shared a concerning new finding in a letter to staff reported by Axios and Reuters. He disclosed that a worker at its supplier, Wichita-based Spirit AeroSystems, discovered incorrectly drilled holes in a number of 737 bodies.

"A supplier notified us of a non-conformance in some 737 fuselages," Deal said, explaining that the holes "may not have been drilled exactly to our requirements." The problems were all in aircraft that have yet to be delivered to airlines, so Boeing is taking steps in the manufacturing process to ensure complete safety by the time the planes get in the air.

As a result, they'll have to spend some extra time ensuring every plane is up to their standards, even though Deal reassured employees it's not a cause for concern. "While this potential condition is not an immediate safety issue and all 737s can continue operating safely, we currently believe we will have to perform rework on about 50 undelivered planes," Deal said. "While this delay in shipment will affect our production schedule, it will improve overall quality and stability."

Related: Door Plug, Cell Phones From Alaska Airlines Flight Found in Suburban Neighborhood

United Airlines found problems with its own MAX 9s following an investigation, while Alaska has returned its MAX 9s into service.