In a significant update to the investigation of last year’s fatal UPS cargo plane crash in Louisville, Kentucky, federal safety officials have identified the precise component that failed, shedding light on a part with a known history of issues. The National Transportation Safety Board (NTSB) revealed on Wednesday that a critical bearing housing in the left engine mount of the MD-11F aircraft fractured, causing the engine to detach and leading to the fiery accident that killed 15 people.
The crash occurred on November 4, 2025, when UPS Flight 2976, bound for Hawaii, failed to climb beyond 30 feet after takeoff from Louisville Muhammad Ali International Airport. The left engine separated from the wing, creating a massive fireball that engulfed the aircraft as it plowed into industrial buildings near the runway. Three pilots on board and 12 individuals on the ground lost their lives in the incident, which left a half-mile-long debris field and triggered a blaze visible for miles.
Investigators focused early on the engine mount assembly, and the latest report specifies that a 3-inch-wide metal housing around a spherical bearing—key to securing the engine—showed signs of metal fatigue and cracking. This component, known as the bearing race, split into two pieces, allowing the engine to break free. The NTSB released previously unseen images of the damaged part, highlighting the severity of the failure.
Notably, the failed part had a documented history of problems. Boeing, which took over support for the McDonnell Douglas-built MD-11 after a 1997 acquisition, issued a service letter in 2011 alerting airlines to four previous failures of similar bearing races on three different MD-11 aircraft. However, at that time, Boeing determined that these failures did not constitute a ‘safety of flight condition’ and recommended visual inspections at five-year intervals, rather than mandatory repairs.
The adequacy of this response is now under scrutiny. Former federal crash investigators, such as Jeff Guzzetti, have questioned why the 2011 bulletin did not classify the issue as a safety threat, especially since a similar problem was identified in a 1980 service bulletin for the DC-10, the MD-11’s predecessor. The UPS plane had last undergone a detailed inspection of the engine mount in October 2021, and was not scheduled for another until approximately 7,000 more flights, raising concerns about maintenance schedules for aging aircraft.
The crash has prompted the grounding of all remaining MD-11s and related DC-10s still in service, primarily with cargo carriers like UPS and FedEx. These planes, which airlines phased out of passenger service years ago due to inefficiency, have continued to fly in freight operations and firefighting roles. The incident underscores the challenges of maintaining older airframes and the potential risks when known defects are not addressed more aggressively.
Legal implications are already emerging, with the first lawsuit filed last month citing the NTSB’s findings. Attorneys representing victims’ families argue that Boeing and UPS had warning signs that should have prevented the tragedy. Both companies have expressed condolences but declined to comment on the ongoing investigation, while the Federal Aviation Administration (FAA) has not issued an airworthiness directive based on the 2011 bulletin.
Looking ahead, the NTSB’s full investigation is expected to take 18 to 24 months, with a final report detailing probable causes and safety recommendations. This update marks a critical step in understanding the crash, but it also highlights broader issues in aviation safety, including the need for enhanced maintenance protocols and timely responses to component failures in older aircraft fleets.
