An engine part suspected of causing the crash of a UPS cargo plane and loss of 15 lives in Louisville in November was the subject of at least four previous failures on three separate aircraft, investigators have found.
A preliminary report by the National Transportation Safety Board (NTSB) released Wednesday determined that Boeing warned plane owners about the defect, but did not believe it was a flight safety issue and did not require immediate repairs.
Freight companies UPS and FedEx temporarily grounded their fleets of MD-11s, manufactured by McDonnell Douglas before its takeover by Boeing, after the 4 November 2025 crash at Muhammad Ali international airport when an engine on the plane’s left wing caught fire and detached.
The aircraft’s crew of three were killed, along with 12 people on the ground, with the most recent person dying on Christmas Day. The crash is the subject of at least one lawsuit, with relatives of a woman who died on the ground claiming UPS was negligent for keeping the MD-11 aircraft in service, despite known maintenance problems.
The NTSB previously said that investigators found cracks where the plane’s engine connected to its wing. Its investigative update published Wednesday revealed that Boeing sent a service letter to MD-11 owners in February 2011 advising of the earlier failure of a “spherical bearing race” assembly, which helps secure engines to wings, on four occasions, and on three separate aircraft.
“Boeing did not consider it a safety of flight issue,” the report said, and consequently the company recommended only scrutiny of the part during regularly scheduled general inspections, generally every 60 months, instead of immediate rectifying action.
A Boeing spokesperson said in a statement: “We continue to support the investigation led by the NTSB. Our deepest condolences go out to the families who lost loved ones and our thoughts remain with all those affected.” The statement did not address the findings of the report.
UPS spokesperson Jim Mayer said in a statement: “We remain profoundly saddened by the Flight 2976 accident. Our thoughts continue to be with the families and Louisville community who are grieving, and we remain focused on the recovery effort.”
UPS previously said it would not comment on existing or pending legislation.
The plane that crashed in Louisville was a MD-11F version of the aircraft, a successor to McDonnell Douglas’s workhorse DC-10, with three engines. The 34-year-old plane crashed into an industrial complex close to the airport at about 5.15pm, immediately after take-off, causing a massive fireball.
Witnesses said the plane took off with fire on one wing, and the engine detaching as it tried to gain height. Footage aired by WLKY, a CBS affiliate, showed the moment of impact, fires in several buildings of the industrial area beyond the runway, and thick black smoke rising into the sky.
The Associated Press reported the cracks were not spotted during the plane’s most recent maintenance inspection. It said the last time the engine mount parts were examined closely was in October 2021, and the next inspection was not due for about another 7,000 takeoffs and landings.
Jeff Guzzetti, a former crash investigator for the Federal Aviation Administration and NTSB, told the AP that the now defunct McDonnell Douglas sent out a bulletin in 1980 that did identify failures of the spherical bearing race as a “safety of flight condition”.
“It raises questions regarding the adequacy of the severity of the 2011 service letter, and it also raises questions about how UPS incorporated that information and acted upon it,” Guzzetti said.
The Kentucky tragedy has parallels in the 1979 crash in Chicago of an American Airlines DC-10 that killed all 271 on board and led to the global grounding of the fleet. DC-10s, which had a checkered safety record, were allowed to return to flight after it was determined a maintenance crew had damaged the aircraft with a forklift when they reattached the engine.
