Boeing spaced out MD-11 inspections, even after reports of fractured parts

WASHINGTON - Boeing increased the length of time between inspections for a critical part of the MD-11 hardware that holds the plane's engine to its wing - despite multiple reports of previous part failures that had occurred within a shorter inspection interval.

That revelation came Wednesday, as federal investigators held a hearing to examine what factors led to a catastrophic MD-11 crash in November. A UPS MD-11 cargo plane crashed in Louisville, Ky., shortly after takeoff, when the plane's engine and pylon separated from the wing and sailed over the fuselage. The crash killed three UPS crew members on board and 12 other people on the ground.

In the months after the crash, investigators from the National Transportation Safety Board found parts of the hardware that attaches the pylon to the wing had fractured. The engine attaches to the pylon, which then attaches to the wing. The NTSB found signs of fatigue cracks and overstress failures in the spherical bearing race and the two lugs housing that component.

On Tuesday, the first day of the NTSB's hearing, the safety board released documents that showed Boeing had received 10 reports of fractures in the spherical bearing race from 2002 to 2022. Several of those reports also mentioned concerns with lugs in the same part of the aircraft structure, known as the pylon aft mount bulkhead.

Still, in 2014, Boeing asked the Federal Aviation Administration for permission to increase the inspection interval for the lugs, moving from an inspection every 19,900 flight cycles to 29,200 flight cycles.

To make that ask, Boeing said it relied on testing and analysis done when McDonnell Douglas first designed and certified the MD-11 in the 1980s and 1990s. Boeing merged with McDonnell Douglas in 1997 and inherited the trijet, before stopping production just a few years later. Boeing is now responsible for the airplane's maintenance and inspection protocols.

The original McDonnell Douglas testing found that the lug could withstand about 29,200 flight cycles before it showed signs of fatigue, Justin Konopaske, the director of airframe service engineering for Boeing Commercial Airplanes, said Wednesday at the NTSB hearing.

Following FAA regulations at the time, McDonnell Douglas decided on a lower inspection threshold of 19,900 flight cycles, Konopaske said. In 2014, Boeing turned back to that original fatigue testing analysis, he said.

But before it requested to lengthen the inspection interval in 2014, Boeing had received five reports of the spherical bearing, which is housed within the lugs, fracturing long before the plane hit its designated inspection interval, according to documents shared by the NTSB.

In two instances, the fracturing occurred before 15,000 flight cycles. In the other three, the part fractured before 10,000 flight cycles.

On Wednesday, NTSB Chair Jennifer Homendy questioned Boeing on its decision to increase the inspection interval when it was aware of past failures, and asked why it relied on decades-old analysis while overlooking how the plane had performed in recent years.

"You didn't even get to 19,900 cycles but then you put in an application, a change," Homendy said. "Seemingly no one looked at these in-service failures."

The FAA approved Boeing's request, according to documents shared by the NTSB this week. In a 2015 letter regarding the inspection interval request, the FAA wrote "we have determined that the changes … provide an acceptable level of safety."

On Wednesday, Todd Martin, an FAA manager, said he did not believe Boeing had submitted all of the previous reports of bearing race fractures to the regulator when it submitted its request to change the inspection interval.

The FAA had received some reports of the bearing race failure through an internal system Boeing and the FAA use to respond to operators. But the regulator did not search through that database when it responded to Boeing's request, Martin said.

That's not a part of its normal process. "We rely on the applicant," he said.

The FAA was aware of two service letters Boeing had sent to MD-11 operators regarding the bearing race fractures, prompting Homendy to ask why the FAA didn't consider that information in its decision.

I'm confused why you wouldn't ask for more information, more testing, why you just accept information that Boeing provided in the late '80s during certification, 30 years earlier," Homendy said.

"Respectfully, to Boeing, if you submit two weeks from now an increase in the inspection interval, how does FAA know they're getting all the right information, Homendy continued.

Boeing made its inspection interval request as part of a broader ask to change inspection cycles for about 100 MD-11 parts that were considered to be critical to flight safety, also known as principal structural elements.

The lugs are included in that bucket but the bearing race is not. During the NTSB's hearing this week, board members and experts questioned why McDonnell Douglas had made that decision, and if it should be changed in light of the deadly Louisville crash.

Martin, from the FAA, said the distinction depends on whether the failure of the bearing race would affect the overall structural integrity of the airplane. McDonnell Douglas and the FAA originally determined that it would not, because of the two lugs surrounding the bearing race. The recent MD-11 crash changes that assumption, Martin said.

"It's not intuitive or obvious that the failure of the bearing race would impact, or adversely affect the aft lug," Martin said. "So the decision back in 1990 could be seen as reasonable, but given what happened, in this case, it seems the failure of the bearing affected the aft lugs."

A change to that designation is under consideration, Martin said.

After the hearing, an FAA spokesperson said "safety is and always will be the FAA's top priority. We value the NTSB's expertise and input and have worked side-by-side with the NTSB throughout this accident investigation."

The NTSB will continue to investigate the crash to determine a likely cause. At the end of its investigation, the safety board will issue recommendations in an effort to prevent a similar situation from occurring in the future.

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This story was originally published May 20, 2026 at 4:53 PM.