The U.S. National Transportation Safety Board (NTSB) has revealed that a critical engine-mount component that failed in the November 2025 UPS cargo plane crash had failed four times previously on other aircraft, but was not classified as a flight safety risk at the time.
The 34-year-old MD-11, operated by UPS, crashed shortly after takeoff from Louisville, Kentucky, when its left engine detached from the wing, killing three crew members and 12 people on the ground. The aircraft was carrying thousands of packages and tens of thousands of gallons of fuel.
According to the NTSB, Boeing documented the prior failures in a 2011 service bulletin, inherited from McDonnell Douglas, but determined they did not pose a “safety of flight” condition. The FAA did not issue a mandatory airworthiness directive, and operators were allowed to continue using older bearing designs known to be failure-prone.
Investigators found cracks in the spherical bearing race and engine mount lugs, which were not detected during routine maintenance. The last detailed inspection occurred in 2021, with the next not due for another 7,000 cycles. Experts say the crash echoes the 1979 American Airlines DC-10 disaster, which also involved engine separation.
The NTSB has not yet issued a final cause, but the bearing failure is a central focus. The findings are expected to play a key role in ongoing and future lawsuits, raising questions about Boeing’s risk assessment, UPS’s maintenance decisions, and the continued operation of ageing MD-11 aircraft.