Overview
- Investigators found the spherical bearing race in the left pylon aft mount fractured, with fatigue initiating at a design recess groove and about 75% of the fracture surface showing fatigue.
- The failure mode matches a 2011 Boeing service letter that noted four prior bearing‑race failures on three MD‑11s, which Boeing then judged not a safety‑of‑flight condition while advising 60‑month visual checks and a newer part design.
- The NTSB is reviewing how that 2011 guidance was incorporated into maintenance programs, UPS’s compliance with it, and Boeing–FAA correspondence related to the issue.
- Flight data showed No. 1 engine parameters became unreliable shortly before the end of the recording with a fire indication, and airport video captured the left engine and pylon separating followed by a fire.
- The FAA issued an Emergency Airworthiness Directive requiring inspections that temporarily grounded MD‑11s and later extended the mandate to related DC‑10/MD‑10 variants, and the NTSB has not assigned probable cause.