air-cargo

NTSB Probes Why MD-11 Pylon Bearing Failures Went Unaddressed Before Fatal UPS Crash

Investigators are examining why repeated bearing failures on Boeing MD-11 engine pylons did not trigger adequate preventive measures before a UPS freighter crashed during takeoff from Louisville last November. The National Transportation Safety Board determined that fatigue in the bearing race between pylon bulkhead lugs caused stress fractures in both lugs, leading to left engine separation on rotation. Three FedEx aircraft experienced similar bearing race failures since June 2020, while three of 26 inspected UPS MD-11Fs showed identical problems in one pylon each. NTSB member John DeLeeuw expressed concern that earlier discoveries represented warning signals ignored by the industry. A May 2008 service letter addressing the failures was classified as non-safety-critical, potentially misdirecting corrective action protocols. A 2011 revision introduced a redesigned bearing intended to eliminate the lubrication groove in the race.