Single point of failure: engine leaving wing in Louisville reminder of decades-old aviation lesson

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By Vincent E. Bianco III

August 9, 2026, © Leeham News: On the evening of November 4, 2025, a UPS-operated MD-11 freighter rolled down runway 17R at Kentucky’s Louisville Muhammad Ali International Airport. The taxi was normal. The roll was routine. Then, at rotation, the left engine and its pylon tore off and arced over the wing, trailing fire, and the airplane—a 34-year-old trijet UPS was planning to retire, loaded with fuel destined for Honolulu—climbed about 30 feet, rolled left, and came down across a petroleum-recycling yard and an adjacent warehouse. Black smoke and flames rose high over Louisville.

Three crew died in the accident. According to the US National Transportation Safety Board (NTSB), 11 people on the ground were also killed; another died in a hospital weeks later.

A bell rang at rotation and kept ringing—25 seconds of alarm, the cockpit voice recorder shows, that did not tell the flight crew the engine had left the wing. They had no diagnosis. They had very low altitude. They had a catastrophically damaged airplane.

The UPS crash file is still open. But the preliminary report, an investigative update, and two days of public hearing in May have already surfaced the proximate culprit, and it is a small one. The pylon’s aft mount depends on a single spherical bearing. Its race fractured. The NTSB’s metallurgists found fatigue running through the fracture, finished by overstress—which is to say the part was most of the way dead before the airplane ever moved, and the last sound margin let go on rotation.

The crash site of the MD-11 that lost its No. 1 engine on rotation during a failed take-off in Louisville, Kentucky in November, 2024. Photo credit: US National Transportation Safety Board

That is a single point of failure in the most literal sense: one part, no partner, and when it went the engine went with it. The airport cameras caught the whole sequence in a handful of frames—the engine lifting off its mount, riding up and over the leading edge, the fireball blooming at the wing root—images stark enough that the NTSB released them with the preliminary report.

But the bearing is only the near cause. The hearing surfaced a deeper one. A February 2011 Boeing service letter had already named this exact failure—bearing races cracking at the same machined groove, on other airplanes, years earlier. A redesigned bearing without the offending groove existed. Its installation was recommended, not required, and the old part was never prohibited. Across the fleet the failure recurred—by the NTSB’s accounting at least 10 times since 2002, four on FedEx MD-11s alone between 2017 and 2022. The reporting scattered exactly as a broken aggregation system would predict. Of the 10 incidents, seven reached Boeing, four reached the FAA, only two reached both—and the most recent, in December 2022, reached no one at all. Pieces of the picture existed but nobody put it all together.