US safety investigators are scrutinizing why known problems with McDonnell Douglas MD-11 engine pylon hardware did not avert the fatal UPS Airlines Flight 2976 crash in Louisville, Kentucky. The US National Transportation Safety Board (NTSB) says fatigue cracking found in the No. 1 engine’s pylon attachment on the UPS MD-11F appears consistent with a failure mode flagged to operators more than a decade earlier.
UPS Flight 2976, operating from Louisville to Honolulu on November 4, 2025, crashed shortly after takeoff when the left engine and pylon separated from the wing soon after rotation. The cargo jet was destroyed, killing all three crewmembers and 11 people on the ground, and injuring more than 20 others.
According to an investigative update, the NTSB identified fatigue cracking on the interior surface of a spherical bearing race within the engine mount assembly. A 2011 Boeing service letter, MD-11-SL-54-104-A, had warned operators of four prior bearing race failures on three MD-11s and outlined inspection and replacement guidance. The NTSB is now examining how that service letter was implemented at UPS and reviewing related exchanges between Boeing and the Federal Aviation Administration.
The board has emphasized that it has not yet determined the extent to which the bearing race failure contributed to the crash. However, the pattern of earlier pylon and bearing issues, and the apparent convergence with the Louisville findings, has sharpened its focus on whether regulatory oversight, manufacturer guidance, and operator compliance were sufficient to mitigate a known structural risk on the MD-11 fleet.