UPS Flight 2976: NTSB Investigation Reveals Prior Warnings of Catastrophic Engine Failure
A National Transportation Safety Board investigation has determined that fatigue cracks in a critical engine mounting component caused the left engine of a UPS McDonnell Douglas MD-11F cargo aircraft to separate during takeoff, killing 15 people in Louisville, Kentucky, on November 4, 2025.
The Accident
On November 4, 2025, UPS Flight 2976, a McDonnell Douglas MD-11F cargo aircraft, was preparing for takeoff from Runway 17 Right at Louisville Muhammad Ali International Airport. The aircraft—bound for Honolulu, Hawaii, with a full load of jet fuel—had been assigned to the flight after the original plane was taken out of service for a fuel leak.
As the flight crew initiated takeoff thrust, a bell sounded in the cockpit approximately 37 seconds later. The bell continued to ring for 25 seconds as the aircraft neared takeoff speed. Airport surveillance video captured the left engine separating from the wing in a fireball during the takeoff sequence.
The aircraft briefly lifted off, reaching no higher than 30 feet above the runway, before crashing into a petroleum recycling facility and a UPS warehouse. The resulting fire damaged multiple structures.
Casualties
- 15 fatalities: Three crew members aboard the aircraft and 12 individuals on the ground
- 23 people on the ground reported injured
- Rescue operations searched buildings affected by the fire
NTSB Investigation Findings
The NTSB investigation identified the failure of a component known as a spherical bearing race and its mounting structure as the cause of the left engine detachment. This metal housing, approximately three inches wide, was integral to the mount securing the engine to the wing.
Investigators determined that the fracture in the bearing race and support structure was due to metal fatigue from repeated stresses. The NTSB released images and an animated video illustrating the failed components.
Prior Warning and Industry Knowledge
In a critical finding, the NTSB report highlights that Boeing—which acquired McDonnell Douglas in 1997—had identified four previous failures of the same part on three different MD-11 aircraft prior to the 2025 crash.
Year Action Taken 2011 Boeing issued a "service letter" to operators (a non-legally binding document) detailing these failures 2011 Boeing concluded the issue "would not result in a safety of flight condition" 2011 Boeing recommended a general visual inspection every five years and made a revised bearing assembly available—though installation was not mandatory"The 2011 notification did not require action." — UPS statement
An NTSB investigator disclosed that UPS did not take additional action after reviewing the 2011 notification.
Investigation and Hearings
The NTSB conducted a two-day fact-finding hearing that included testimony from UPS, the Federal Aviation Administration (FAA), and Boeing. The NTSB released over 2,000 pages of related documents.
A final NTSB report—which will detail the probable causes of the crash and provide safety recommendations—is expected to be completed in 18 to 24 months. Analysis of the flight data recorder is being performed to determine why the aircraft's altitude did not increase.
Aftermath and Fleet Actions
Regulatory Action
The FAA issued an emergency directive grounding all McDonnell Douglas MD-11 aircraft, citing an "unsafe condition likely to exist or develop in other products of the same type design." The order was later lifted after Boeing issued updated instructions. The FAA approved Boeing's plan to replace the spherical bearings and increase inspection frequency on MD-11s.
Fleet Groundings
Following the crash, both UPS and FedEx—the two largest operators of MD-11 cargo aircraft—announced the grounding of their MD-11 fleets.
- UPS: The grounding impacted 9% of its fleet. UPS CEO Carol Tomé announced the retirement of all remaining MD-11 aircraft, replacing them with Boeing 767 aircraft. (UPS had announced plans in 2023 to replace MD-11s with Boeing 767s.)
- FedEx: Began returning its MD-11s to service on May 10, 2025, after implementing a new bearing in the engine mount.
- Western Global Airlines: Has not announced its plans.
Aircraft History
The MD-11 aircraft involved in the crash began service 34 years ago as a passenger jet with Thai Airways before being transferred to UPS in 2006. The MD-11 series was originally manufactured by McDonnell Douglas and later by Boeing. Production of MD-11 planes concluded in 2000.
Potential Operational Impact
At the time of the grounding:
- MD-11 aircraft constituted approximately 9% of the UPS airline fleet and 4% of the FedEx fleet
- Holiday package deliveries were projected to increase by 5% that season
"While UPS and FedEx communicated that contingency plans were in place, experts noted that the grounding could affect capacity and potentially delay packages during the holiday period if the grounding extended beyond one to two weeks."