The NTSB has released a preliminary report on the crash of a McDonnell Douglas MD-11 in Louisville

According to the report, taxiing and the takeoff roll were normal. The problems began at liftoff. Airport surveillance footage showed that shortly after the aircraft’s nose lifted off the runway, the left engine, along with its pylon - the structure attaching the engine to the wing - separated from the left wing. While still airborne, a fire ignited in the area of the detached engine, which flew over the fuselage and fell to the ground near the runway. A fire also broke out at the pylon-to-wing attachment point and continued burning until the aircraft impacted the ground.

After liftoff, the aircraft managed to climb only about 30 feet. It cleared the fence at the end of the runway, but then struck the roof of a UPS warehouse near the airport’s southern boundary with its left landing gear. It then crashed through an open-air storage area and two additional buildings, including a petroleum processing facility. Spilled fuel triggered a large fire. All three pilots on board were killed. On the ground, 11 people died and more than 20 others were injured.

The tower controller noted that the aircraft’s takeoff roll speed appeared normal for this type of plane, but the rate of climb was unusually low - the plane never climbed higher than the control tower, roughly 200 feet tall. Another witness reported that the aircraft first stopped climbing, then began to descend, banking to the left before crashing.

The crew was highly experienced. Both the captain and first officer had thousands of hours on the MD-11. A relief pilot with significant total flight time was also on board.

Both the cockpit voice recorder and flight data recorder were recovered and successfully downloaded. They contained data not only from the accident flight but also from previous flights.

Investigators are focusing on the engine-to-wing attachment point. On the MD-11, engines are mounted beneath the wings using pylons that connect at multiple points - a forward mount that bears thrust loads, and an aft mount with a spherical bearing assembly. It was this aft attachment on the left pylon that failed. Wreckage analysis revealed parts of the pylon, fittings from the rear mount, and a section of the wing with a bolt and fractured spherical bearing still in place.

At the NTSB lab, after cleaning the fracture surfaces, investigators found not only signs of overload failure but also evidence of fatigue cracking in the rear mount’s fittings - cracks that grow slowly over time under repeated stress. On some surfaces, the cracks originated from the bolt holes; others showed signs of sudden failure. The bearing itself was also destroyed.

The aircraft was 34 years old, with nearly 93,000 flight hours and about 21,000 takeoff and landing cycles. UPS maintained it under a continuous airworthiness program. According to company procedures, the rear pylon attachment was subject to visual inspection every six years - the last one occurred in 2021. A separate lubrication of the struts and spherical joints was performed about two weeks before the crash. A more detailed inspection of this attachment point had been scheduled for a later date.

Following the crash, UPS temporarily grounded its MD-11 fleet. Shortly after, the FAA issued an emergency airworthiness directive effectively grounding all MD-11 and MD-11F aircraft until inspections and potential defects were addressed. Within days, the directive was expanded to include DC-10 aircraft, which have a similar engine mounting design. A global inspection effort of these aircraft was launched.

In its preliminary report, the NTSB references the 1979 crash of an American Airlines DC-10 near Chicago. In that case, the left engine and pylon also separated during takeoff, causing the aircraft to lose control and crash, killing 273 people. That accident was attributed to a combination of design issues and improper maintenance procedures. Investigators are now examining whether a similar combination of factors played a role in the