After UPS plane crash, 10 similar flaws were recorded. NTSB says no one raised an alarm

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After the engine flew off a UPS cargo plane and caused a crash that killed 15 people in Kentucky, investigators found records of 10 previous flaws in the same key parts that help secure engines to wings of other similar planes — most of them never reported to the Federal Aviation Administration.

The National Transportation Safety Board focused Tuesday on why no one in government or the industry spotted the concerning trend and took action to prevent it before last November’s crash. Investigators also released more than 2,000 pages of related documents as the board began two days of hearings in Washington to examine the disaster's root causes.

The engine separated from the MD-11’s left wing as it accelerated down the runway Louisville’s Muhammad Ali International Airport. The crash killed all three pilots on the plane and 12 people on the ground. Twenty-three more were injured.

FAA and UPS officials said the reports they did get about problems related to the spherical bearings that have been a focus of the crash investigation may not have included enough information. UPS's David Springer said Boeing's service letters made the bearing problem “sound almost benign” and didn't mention any of the collateral damage that could be caused to the lugs that attach the engine to the wing.

“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.

The hearings at the NTSB headquarters involve rounds of questions and answers among board members, investigators, and representatives of Boeing, UPS, the mechanics’ union and other parties. The NTSB’s final report likely won’t be ready until more than a year after the crash because it will look at every potential factor.

Here’s what you should know:

The documents released Tuesday revealed that UPS switched planes hours before the crash, after a preflight inspection found a fuel leak in the first plane loaded for the trip to Hawaii. The cargo was then loaded onto a second plane, and the flight crew shared good-natured banter with the maintenance team during its inspection about “meeting again” so soon.

This second plane promptly lost its left engine, and barely cleared the airport fence before crashing into nearby businesses in a massive fireball.

Dramatic images the NTSB released after the crash showed the engine detaching as flames erupted on the wing. The plane was already ablaze as it briefly got airborne, leaving behind trails of smoke.

Examining the wreckage, investigators found cracks in some of the parts that held the engine to the wing, the NTSB said. Those cracks hadn’t been caught in regular maintenance, which raised questions about the adequacy of the maintenance schedule. The last time those key engine mount parts were examined closely was in October 2021, and the plane wasn’t due for another detailed inspection for roughly 7,000 more takeoffs and landings.

Meanwhile, all MD-11s and DC-10s, a predecessor aircraft, were grounded after the Louisville crash. NTSB investigators said Tuesday that similar part flaws were subsequently found in three other UPS planes and a DC-10.

NTSB member Tom Chapman said investigators also found 10 different earlier examples of flaws in MD-11s, dating back more than 15 years, involving the same key part that failed in Louisville, but only four were reported to the FAA. Chapman said all of them should have been reported. FAA officials testified Tuesday that four, spread over years, would not have been enough to demonstrate a problem trend.

Boeing determined that those flaws “would not result in a safety of flight condition,” so the plane maker didn’t require plane owners to make repairs. And the FAA never issued an airworthiness directive that would have ensured that was done. Instead, Boeing just recommended replacing the bearings with a redesigned part that was less likely to fail.

UPS officials told the NTSB that they could have done more to prevent the crash if they had only known more.

The Louisville disaster was reminiscent of a 1979 crash in Chicago involving a DC-10. The left engine also fell off in that crash, which killed 273 people and led to the worldwide grounding of 274 DC-10s.

The airliner returned to the skies because the NTSB determined that maintenance workers had damaged the plane that crashed while improperly using a forklift to reattach the engine. That meant the crash wasn’t caused by a fatal design flaw even though there had already been a number of accidents involving DC-10s.

But even at that point, the plane’s manufacturer, McDonnell Douglas, raised concerns about the spherical bearing that helps hold the engines to the wings. McDonnell Douglas later merged with Boeing.

Some MD-11s, a workhorse of the cargo fleet, are now back in the air after the FAA approved Boeing's plan to replace the spherical bearing on each aircraft and increase inspections.

FedEx resumed using the planes to deliver packages on May 10, but UPS has said it plans to retire its fleet of MD-11s. Western Global also uses MD-11s but hasn’t said what it plans to do.

Some experts speculated after the crash that the MD-11s might never fly again if the repair proved to be more expensive that it was worth in these older planes. But Boeing said it found a way to address the safety concerns simply by replacing the bearing and stepping up inspections.