US investigators are examining why repeated failures involving Boeing MD-11 engine pylon bearings did not lead to stronger corrective measures before the fatal crash of a UPS freighter in Louisville last November.
During a hearing on May 19, the National Transportation Safety Board (NTSB) released new surveillance video showing the left engine and pylon separating from UPS Flight 2976 shortly after takeoff from Louisville Muhammad Ali International Airport.
The MD-11F, operating a cargo flight to Honolulu, crashed moments after lifting off on November 4, 2025. Fifteen people were killed, including the three crew members and 12 people on the ground.
According to investigators, fatigue cracks developed in a bearing race located between two structural lugs connecting the aft section of the pylon to the wing. The NTSB believes the fractured lugs allowed the left engine and pylon to detach during rotation.
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The hearing revealed that similar bearing race failures had previously been identified on several MD-11 aircraft, including three FedEx freighters since 2020.
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UPS also inspected its fleet after the accident and found the same condition on three of its remaining 26 MD-11Fs.
NTSB board member John DeLeeuw said the earlier discoveries should have been treated as warning signs before the accident.
“We had something here, we just didn’t do anything about it,” he said during the hearing.
Investigators also reviewed Boeing service documents issued in 2008 and 2011 that addressed bearing failures and introduced revised inspection procedures and a redesigned bearing component.
UPS engineering officials told the hearing that Boeing’s documentation did not characterize the issue as a flight safety risk and failed to explain the extent of structural damage that could result from the bearing failures.
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The NTSB also questioned Boeing over its use of FAA service difficulty reports, which had documented multiple cases involving the same component over the years.
Boeing said it had not routinely used the FAA database for trend analysis because of concerns over data quality, but added it is now reviewing how to improve the process with regulators.
The accident intensified scrutiny over the aging MD-11 fleet. UPS retired its remaining MD-11 freighters at the end of 2025, while FedEx later returned its aircraft to service after the FAA lifted temporary restrictions.
