Stan Deal, the chief executive of Boeing's commercial plane unit, wrote in a memo to employees on Sunday that the Renton, Washington, factory will "spend several days" to focus on "quality, including inspecting some undelivered airplanes for a potential nonconformance prior to delivery." 

"This past Thursday, a supplier notified us of a nonconformance in some 737 fuselages. I want to thank an employee at the supplier who flagged to his manager that two holes may not have been drilled exactly to our requirements," Deal said. 

He noted this production issue "could delay some near-term 737 deliveries" as the factory "will have to perform rework on about 50 undelivered airplanes." 

Deal didn't name the supplier. However, Reuters confirmed that fuselage supplier Spirit AeroSystems discovered two misdrilled holes. 

Deal stressed that "this potential condition is not an immediate flight safety issue, and all 737s can continue operating safely, adding, "While this delay in shipment will affect our production schedule, it will improve overall quality and stability." 

The misdrilled holes disclosed yesterday are yet another problem for the 737 program. 

In August, Boeing identified a manufacturing problem in the aft pressure bulkhead on specific Max jets, which helps maintain cabin pressure. This production issue stems from Spirit AeroSystems, which builds 70% of the narrowbody jet frames. In December, a separate issue of a possible loose bolt in the rudder control system of Max jets was reported. 

Boeing shares were lower 2% in premarket trading on the news. Shares have traded sideways for several years since the two Max crashes, killing 346 people. The first crash was in 2018, and the second in 2019.