NTSB: 10 Prior MD-11 Bearing Failures Preceded Fatal UPS Flight 2976 Crash

LOUISVILLE, Ky. — At least 10 prior incidents involving the same pylon bearing and structural lugs on MD-11 and MD-11F aircraft were documented worldwide since around 2002, according to NTSB investigative hearings on UPS Flight 2976. The crash occurred at Louisville Muhammad Ali International Airport during the takeoff roll, resulting in the separation of the left engine from the wing.

Investigation Reveals Reporting Gaps

The National Transportation Safety Board opened a major investigation including detailed teardown of the pylon assembly and failed inboard thrust-link bearing. Fatigue cracking led to bearing failure and eventual separation of the engine from the wing structure during takeoff. Of the 10 known bearing-related events documented, only four were formally reported to the Federal Aviation Administration via the Service Difficulty Reporting system. Six events were not captured, creating a gap in regulatory awareness.

Hearing testimony highlights significant reporting failures. Boeing representatives acknowledged awareness of multiple in-service events and a Continued Operational Safety case opened after a 2007 incident. However, the NTSB questioned why numerous lug-damage events and bearing anomalies over nearly two decades were not consistently entered into the COS process. UPS reported using the SDR database mainly as a reporting tool rather than a research tool, meaning they did not routinely mine SDR for trend data on similar MD-11 events.

Calls for Reform

The findings point to a long-term pattern of under-reporting on safety-of-flight issues. Boeing received reports of cracked bearings and deformed bulkhead lugs in March 2017 and June 2020, yet questions remain why those events did not trigger stronger corrective action. During original certification fatigue testing for the MD-11 pylon assembly, no clear documentation exists showing the bearing's condition post-testing or whether its fatigue performance was properly validated. The NTSB has referenced prior recommendations for the FAA to require comprehensive review of service bulletins and improve oversight of manufacturer COS processes.