NTSB says Boeing had 2011 warning about part in UPS Louisville crash

What the NTSB said about Boeing’s 2011 warning

The National Transportation Safety Board said Wednesday that Boeing had documented in 2011 repeated failures of a part tied to how MD-11 engines are secured to the wings, and that Boeing concluded at the time that the information would not amount to a “safety of flight condition.” The NTSB said the part that broke during the UPS crash in Kentucky had failed on other planes before, while Boeing’s view of the risk at the time did not trigger the kinds of safety orders regulators typically issue.

The Louisville crash and the engine separation

The UPS plane crashed shortly after taking off in Louisville, Kentucky, on Nov. 4, 2025, the NTSB said. The aircraft had been headed for Hawaii when the left engine flew off the wing as the plane rolled down the runway, and the crash killed three pilots aboard and 12 people on the ground near Muhammad Ali International Airport.

The NTSB’s report released Wednesday did not state what caused the engine to fly off, but the document made clear that investigators were focused on the engine-mount component and the circumstances around its failure. The NTSB said the ultimate conclusion would come only in the final report, which usually arrives more than a year after a crash.

Maintenance gaps and the last close inspection

The NTSB previously said investigators found cracks in parts that held the engine to the wing, and that those cracks had not been caught in regular maintenance performed on the aircraft. Investigators said the last time the key engine mount parts were examined closely was in October 2021, and that the plane was not due for another detailed inspection for roughly 7,000 more takeoffs and landings.

Investigators also reported that the part broke into two pieces after the UPS crash, and that the lugs that held that component were cracked.

Boeing’s 2011 service bulletin and what it did—or didn’t—require

Boeing documented in 2011 four prior failures of a part that helps secure the MD-11’s engines to the wings on three different planes, the NTSB said. The safety board said Boeing, based on its documentation in 2011, determined that the failures it described would not result in a “safety of flight condition.”

The report also addressed what happened with the bulletin in regulatory terms. The service bulletin that Boeing issued did not require owners to make repairs the way an FAA airworthiness directive would, and the FAA did not issue such a directive, according to the report.

Industry context: similar engine-separation event in 1979

The report said the crash raised issues that were reminiscent of a 1979 disaster in Chicago involving an American Airlines DC-10, when the left engine flew off the wing during takeoff and killed 273 people. That accident led to worldwide grounding of 274 DC-10s, and the report said the DC-10s were later returned to service after the NTSB determined the crash was not caused by a fatal design flaw, but instead involved maintenance workers damaging the plane during the improper use of a forklift to reattach the engine.

What outside investigators said about earlier warnings

Former FAA and NTSB crash investigator Jeff Guzzetti said a 1980 service bulletin issued by McDonnell Douglas identified failures of the spherical bearing race as a “safety of flight condition.” Guzzetti said it was surprising that Boeing did not call it that in 2011, and he said the developments raise questions about the adequacy of the severity of the 2011 service letter and about how UPS incorporated that information and acted upon it.

Former federal crash investigator Alan Diehl said Boeing’s notice recommended replacing bearings with a redesigned part less likely to fail, but that it also allowed operators to replace defective bearings with older bearing parts that had already demonstrated they were prone to failing. Diehl said that as the investigation continues, the NTSB will have to address whether the service bulletin was an adequate solution to a known problem that could have had catastrophic results, and he said the UPS crash highlights a need for increased maintenance measures on older airframes.

Lawsuits expected to use the preliminary findings

The NTSB’s factual report released Wednesday is expected to be cited in the first lawsuit filed last month, with subsequent lawsuits likely to follow, the report said. Brad Cosgrove, an attorney with the Clifford Law firm who filed the first lawsuit, said the warning signs predated the crash that any reasonable organization should have used to make sure the Louisville crash didn’t happen.

What other engines were doing, and reactions from UPS and Boeing

The report said investigators found that neither of the aircraft’s two other engines was on fire before the crash, addressing earlier speculation from some experts that debris from the left engine might have damaged the engine on the tail.

Boeing, UPS and the Federal Aviation Administration declined to comment on Wednesday’s report while the NTSB investigation is ongoing, the report said. UPS spokesperson Jim Mayer said: “We remain profoundly saddened by the Flight 2976 accident.” Mayer added: “Our thoughts continue to be with the families and Louisville community who are grieving, and we remain focused on the recovery effort.”

An older airframe and the response after the crash

The NTSB report said the 34-year-old MD-11 plane got about 30 feet (9.1 meters) off the ground before crashing into industrial buildings just past the runway, generating a fireball visible for miles. The report said all MD-11s that had been in use and 10 related DC-10s have been grounded since the crash.

The report said Cosgrove expects it will become clear that some of the MD-11s “probably should have been retired” and had exceeded their shelf life.