Boeing Aware of Structural Defects Linked to UPS Aircraft Accident

Investigations Reveal Structural Defects in MD-11F Aircraft

An aircraft that caught fire in Kentucky last November was found to have a structural defect identified by Boeing 15 years ago, according to investigations. The MD-11F, operated by UPS, crashed after one of its engines detached from the wing during preparations for takeoff from Louisville. The aircraft briefly lifted off before losing control and falling into an industrial area. The accident resulted in 15 fatalities, including three crew members and 12 individuals on the ground.

In an updated report, the U.S. National Transportation Safety Board (NTSB) revealed that cracks found in the engine mounting assembly had previously been identified on other aircraft. At the time, Boeing concluded that the issue "would not lead to a flight safety condition." The MD-11 is a relatively old model, initially produced by McDonnell Douglas, which Boeing acquired in 1997. The last MD-11 was rolled off the production line in 2001, but Boeing continues to provide parts and technical support.

Following the Kentucky disaster, the NTSB issued a preliminary report highlighting the cracks in the engine attachment mechanism. Subsequent updates described fractures caused by evidence of "fatigue"—or repetitive stress conditions—in a critical bearing and its mounting support. The report indicates that Boeing had previously discovered defects in the same part four times, impacting three different aircraft. In 2011, the company sent a "service letter" to operators warning them of its findings.

Former air crash investigator Tim Atkinson expressed concern about the NTSB update. "The structure in question is not decorative; it is an essential part of the mechanism that attaches the engine to the wing and supports loads such as thrust and friction," he explained. "It is extraordinary that Boeing concluded that a defect in this part would not have safety ramifications."

Boeing has faced criticism in recent years for its internal processes. Critiques have focused on how much the design of the 737 Max aircraft included faulty software that led to two crashes in 2018 and 2019, resulting in 346 deaths. Quality control in its factories has also been scrutinized, following an incident where a door panel fell off a new 737 Max shortly after takeoff in 2024.

In a statement, Boeing said: "We continue to support the investigation led by the NTSB. Our deepest condolences go to the families who have lost loved ones, and our thoughts remain with all those affected." The NTSB investigation continues. So far, it has not issued firm conclusions regarding the cause of the accident and is unlikely to do so until it publishes its final report.