About 14 years before an MD-11 aircraft flown by UPS crashed in Louisville, Kentucky, killing 15 people, Boeing warned about potential problems with the parts holding an engine in place, according to the National Transportation Safety Board.
The NTSB report noted that parts recovered from the assembly that held the left wing’s engine — which fell off the plane — were fractured.
No official cause had been determined for the crash, which came shortly after takeoff from Muhammad Ali International Airport in Louisville, Kentucky, on Nov. 4, killing all three people on the plane and 11 people on the ground as it exploded in a giant fireball.
CrashVision: NEW The latest NTSB investigative update on the tragic UPS Flight 2976 MD-11F cargo crash in Louisville, Kentucky, points to a critical failure in the engine mounting system!
📡 What We Know: On November 4, 2025, the Boeing (McDonnell Douglas) MD-11F (N259UP)… pic.twitter.com/W8V3omJkjA— John Cremeans (@JohnCremeansX) January 15, 2026
“As indicated in the preliminary report for this investigation, airport surveillance videos that captured part of the airplane’s takeoff roll showed that the left (No. 1) engine and pylon separated from the wing shortly after airplane rotation, and a fire ignited on the left engine and near the area of the left pylon wing attachment,” the report said.
“Boeing Service Letter MD-11-SL-54-104-A, dated February 7, 2011, informed operators of four previously reported bearing race failures (on three different airplanes) involving P/N S00399-1spherical bearing assemblies,” the report added.
The report noted that the Service Letter warned that the part which failed could break into two pieces.
“According to the Service Letter, a review of the spherical bearing failure by Boeing determined it would not result in a safety of flight condition,” the new report said.
“The Service Letter stated that, for Boeing MD-11 airplanes, inspection of the spherical bearing assembly would be included in the general visual inspection (GVI) and detailed visual inspection of the pylon aft mount, normally at a repetitive 60-month interval.”
Video from my dads dash cam. Praying for everyone involved. Louisville, KY pic.twitter.com/GTb3BQMmoo
— Anela Hadžić (@NelaHadzic) November 6, 2025
In a statement, a Boeing representative said that the company supports the investigation, according to The New York Times.
After the crash, Boeing called for all MD-11 aircraft to be grounded, UPS said it would stop flying the planes, and the Federal Aviation Administration put a temporary ban on using them.
A preliminary NTSB report in November said parts of the assembly fractured and showed signs of “fatigue cracking” and “overstress failure.”
The initial NTSB report said it was the UPS policy to inspect the part visually every 72 months, which was 12 months longer than the Service Letter suggested.
The initial report said the last visual inspection of the failed part was on Oct. 28, 2021, and the bearings in the assembly that failed were lubricated on Oct. 18, 2025.
The initial report also said that lugs holding the failed part in place were not due for inspection for several thousand landings and takeoffs.
The MD-11 was built by McDonnell-Douglas before the company merged with Boeing, according to FleugzeugInfo.net. About 200 of the aircraft were built between 1990 and 2000.
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