NTSB opens hearings into fatal UPS cargo plane engine separation

Federal safety investigators opened two-day hearings Tuesday into why an engine detached from a UPS MD-11 cargo plane during takeoff last November, killing 15 people at Muhammad Ali International Airport in Louisville, Kentucky, according to ABC7 Los Angeles.

The hearings put under scrutiny Boeing's 2011 decision to classify a documented, recurring bearing failure as a non-safety issue — choosing a non-mandatory service bulletin over a federal airworthiness directive — a judgment investigators now say may have allowed fatal cracks to go undetected for years.

NTSB Chair Jennifer Homendy opened proceedings with a direct address to families of the 15 victims. "Please know: Your loved ones are the reason we're here. We want to find out what happened," Homendy said in opening remarks, ABC7 Los Angeles reported.

At the center of the inquiry is how Boeing responded to a recurring flaw in the spherical bearing that secures each engine to the wing. Boeing's own documents show the company recorded four separate bearing failures in 2011, yet determined the defect would not pose a safety of flight condition. Rather than seeking a mandatory FAA airworthiness directive, Boeing issued a non-mandatory service bulletin.

The ill-fated UPS plane was pressed into service as a substitute after a fuel leak grounded the originally scheduled aircraft. During takeoff, cracks in the spherical bearing caused the engine to detach from the MD-11's wing, sending it flying over the fuselage as flames erupted. Three pilots aboard and 12 people on the ground were killed.

The crash drew comparison to the 1979 accident near Chicago in which a similar engine separation from a DC-10 killed 273 people, according to the ABC7 Los Angeles report. The MD-11 is a derivative of the DC-10. After the Louisville disaster, federal regulators grounded all MD-11s and DC-10s worldwide, and investigators subsequently found similar bearing flaws in three other UPS aircraft and a separate DC-10.

The last detailed inspection of the Louisville plane's engine mount components was carried out in October 2021. Ahead of the hearings, the NTSB released more than 2,000 pages of investigative documents. Testimony is expected from Boeing and UPS representatives as well as mechanics' union officials and flight crew members.

The FAA has since approved a Boeing repair plan allowing some aircraft to return to service. FedEx resumed MD-11 operations on May 10. UPS, whose plane was at the center of the investigation, has announced plans to retire its entire MD-11 fleet.