Overview
- Investigators say the left engine and pylon separated shortly after takeoff, and lab analysis found the bearing race fractured with about 75% of the surface showing fatigue and the rest overstress.
- The failed part was the spherical bearing race in the left pylon aft mount, with cracking that originated at a recessed groove consistent with an older design.
- A 2011 Boeing service letter documented four prior bearing race failures on three MD-11s, judged the issue not a safety-of-flight condition, and called for 60‑month visual checks while not prohibiting the original part.
- The NTSB is reviewing how operators, including UPS, incorporated that guidance and is examining Boeing’s correspondence with the FAA; no probable cause has been assigned.
- Both recorders were recovered, with preliminary data showing normal performance until No. 1 engine parameters became unreliable and a fire indication appeared, and the FAA’s emergency directive temporarily grounded affected fleets pending inspections that enabled return to service.