They have discovered a new problem in the production of Boeing 737 Max aircraft that have not yet been delivered.

(CNN) — A new problem was discovered during production of the 737 Max planes that will force Boeing to rework about 50 planes that have not yet been delivered.

The problem was revealed in a memo sent to Boeing employees on Sunday by Stan Deal, head of the company’s commercial aircraft unit. An employee at Boeing supplier Spirit Aerosystems, which makes the 737 Max aircraft fuselage, notified the planemaker that two holes had not been drilled exactly according to Boeing’s requirements, Deal’s memo says.

“While this potential situation is not an immediate flight safety issue and all 737s can continue to operate safely, we currently believe we will have to rework approximately 50 aircraft that have not been delivered,” he said.

The news about the poorly drilled holes is the latest blow to Boeing’s reputation, which has been battered repeatedly over the past five years, most recently by the horrific crash of a 737 Max 9 flight on January 5, 2024.

An Alaska Airlines flight had its door stopper break that day, leaving a crater in the side of the plane. While the exact cause of the incident is not yet known, Boeing CEO David Calhoun told investors on Wednesday: “We created a problem and we understand it.”

“Whatever conclusion is reached, Boeing is responsible for what happened. Whatever the exact cause of the crash, something like this shouldn’t happen on an airplane leaving one of our factories,” he continued. “We just have to be better.”

Boeing’s 737 Max factory in Renton, Washington, will “dedicate several days this week … to focus on this important work, which demonstrates the importance we place on quality, safety and ultimately sustainability at our factories,” Deal’s memo on Sunday said. is