Federal aviation safety officials will conduct investigative hearings this week to determine what caused an engine to detach from a UPS cargo aircraft during takeoff last year, resulting in a fatal accident that claimed 15 lives, and to examine why Boeing failed to address the known defect earlier.
The engine broke away from the MD-11’s wing while the aircraft was gaining speed on the runway at Louisville’s Muhammad Ali International Airport in November, resulting in the deaths of three pilots aboard the aircraft and 12 individuals on the ground.
The National Transportation Safety Board’s investigative sessions on Tuesday and Wednesday will concentrate on determining the cause of this incident. The agency’s complete report will likely not be completed until more than a year following the accident because the NTSB will examine all potential contributing factors to the crash.
Here’s what you should know:
The UPS aircraft, which was bound for Hawaii carrying packages and fuel, had just become airborne and passed the airport perimeter when it struck multiple nearby Louisville commercial buildings and generated an enormous explosion.
Striking photographs released by the NTSB following the accident revealed the engine separating and launching up and over the wing while flames burst from the wing. The final photographs show the aircraft on fire as it becomes airborne, trailing smoke behind it.
The accident was similar to a 1979 accident in Chicago involving a DC-10, which was the predecessor aircraft to the three-engine jet that crashed in Louisville. The left engine also separated in that accident that resulted in 273 fatalities.
That earlier accident resulted in the global grounding of 274 DC-10s. The aircraft returned to service because the NTSB concluded that maintenance personnel damaged the aircraft that crashed while incorrectly using a forklift to reinstall the engine. This meant the crash wasn’t the result of a fatal design defect despite there having already been multiple accidents involving DC-10s.
However, even then the aircraft’s manufacturer, McDonnell Douglas, expressed concerns about the spherical bearing that helps attach the engines to the wings. McDonnell Douglas subsequently merged with Boeing.
The NTSB stated soon after the Louisville accident that investigators had discovered cracks in some of the components that secured the engine to the wing. Those cracks had not been detected in routine maintenance performed on the aircraft, which raised questions about the sufficiency of the maintenance schedule. The last time those critical engine mount components were thoroughly examined was in October 2021, and the aircraft wasn’t scheduled for another detailed inspection for approximately 7,000 more takeoffs and landings.
Boeing had recorded in 2011 there were four previous failures of a component that helps attach the MD-11’s engines to the wings on three different aircraft, but at that time the aircraft manufacturer “determined it would not result in a safety of flight condition.”
The service bulletin that Boeing released didn’t mandate aircraft owners to make repairs like an FAA airworthiness directive would, and the agency didn’t issue such a directive. At that time, Boeing simply recommended replacing the bearings with a redesigned component that was less prone to failure.
Some MD-11s, a mainstay of the cargo fleet, are now back in service after the FAA approved Boeing’s plan to replace the spherical bearing on each aircraft and increase inspections.
FedEx resumed using the aircraft to deliver packages on May 10, but UPS has stated it plans to retire its fleet of MD-11s. Western Global also operates MD-11s but hasn’t announced what it plans to do with the aircraft.
Some experts predicted after the crash that the MD-11s might never fly again if the repair proved to be more costly than it was worth in these older aircraft. But Boeing found a way to address the safety concerns with just replacing the bearing and increasing inspections.
