Records released during a federal safety hearing on Tuesday revealed that cracks in critical engine-mounting components on cargo aircraft had been discovered at least 10 times over the past 15 years—but only four of those findings were ever reported to aviation regulators.
The National Transportation Safety Board (NTSB) convened a two-day hearing at its Washington headquarters to examine the root causes of the Nov. 4, 2025, crash of UPS Flight 2976, a Boeing MD-11 freighter that lost its left engine and pylon seconds after beginning its takeoff roll at Louisville Muhammad Ali International Airport. The plane climbed no higher than 30 feet before crashing into nearby commercial buildings in a massive fireball.
All three pilots aboard were killed, as were 12 people on the ground. Twenty-three others were injured. One of those on the ground died 51 days after the crash.
"What happened was a systemic failure to recognize and address a known risk before it resulted in a horrific catastrophe," said attorney Bradley Cosgrove, who represents families of the victims, on Tuesday, the first day of the hearing.
NTSB member Tom Chapman said investigators also found records indicating that similar flaws had been found 10 times in other planes during the previous 15 years, but only four were reported to the Federal Aviation Administration (FAA). Chapman said all should have been reported. FAA officials testified Tuesday that four, spread over years, would not have been enough to demonstrate a problem trend.
Investigators are now probing why neither the agency nor the aviation industry identified the trend and intervened before the crash occurred.
A Failure Mode Misunderstood for Years
According to NTSB investigators and Boeing representatives who presented at the hearing, the spherical bearings that connect the engine pylon to the wing are designed to flex slightly under the enormous forces of flight, reducing stress in the assembly. But the lubrication groove carved into the bearing's outer race created a structural weak point, Chihoon Shin, a senior aviation accident investigator, said during a presentation at Tuesday’s hearing.Fatigue cracks formed at the groove's edges, eventually splitting the outer race in two. Without even load distribution, the lugs holding the pylon to the wing were subjected to extreme stress and ultimately fractured, causing the engine and pylon to separate from the wing.
Boeing had analyzed similar bearing failures reported in 2007 and 2008 and concluded they "would not result in a safety of flight condition," Shin said. The company issued service letters recommending more frequent bearing inspections but never changed the actual maintenance schedule, and the FAA never issued an airworthiness directive mandating the work be done—leaving it to individual cargo carriers such as UPS and FedEx to decide whether to take additional action.
FAA safety official Melanie Violette testified that the agency's understanding of how the lug system would fail was fundamentally flawed.
UPS Says It Was Left in the Dark
David Springer, a longtime UPS executive who oversees the company's aircraft maintenance operations, acknowledged during the hearing that Boeing's service letters had not conveyed the severity of the risk. He said the communications made the bearing problem sound "almost benign" and failed to describe the cascading damage the cracked bearings could cause to the lugs—the structural connectors that ultimately failed on Flight 2976."I think if we would have known that at UPS, I think we would have asked a lot of different questions over the years," Springer said.
According to investigators, the critical pylon components on the accident plane had last been closely inspected in October 2021—more than four years before the crash. Another detailed inspection was not scheduled for roughly 7,000 additional takeoff-and-landing cycles.
Some MD-11s Return to the Skies
FedEx resumed flying its MD-11s on May 10, after Boeing developed a fix—replacing the bearings on a regular cycle and stepping up inspections. The FAA approved the plan. Under the new protocol, bearings must now be replaced after every 4,000 takeoff-and-landing cycles.UPS, however, announced it intends to retire its entire MD-11 fleet. Western Global Airlines, which also operates the aircraft type, has not announced its plans.
NTSB Chairwoman Jennifer Homendy, opening the hearing Tuesday, said no findings or recommendations would be issued at this stage, noting that the board's final report—which will not be released for more than a year—must be taken seriously once complete.
"If they are not taken seriously, if they are not implemented, we will be here again," Homendy said. "None of us want that."