Boeing warned MD-11 operators in 2011 about a broken engine attachment but never flagged the failure as critical to flight safety before a UPS freighter aircraft crashed on Nov. 4 when its left-engine pylon separated from the wing during takeoff, the National Transportation Safety Board said Wednesday.
More than 60 FedEx, UPS and Western Global cargo jets have been grounded since the accident in Louisville, Kentucky,, which resulted in the death of three crew members and 12 people on the ground. The NTSB in November said investigators found fatigue cracks in components housed within the left pylon aft mount bulkhead.
The NTSB on Wednesday said Boeing issued a service bulletin 14 years ago in which it disclosed four previous separations of a spherical bearing assembly that helps hold the engine to the MD-11’s wing. The manufacturer said two sections of the assembly came loose on three different aircraft. The letter advised airlines to conduct visual inspections of the part at 60-month intervals.
Boeing recommended replacing faulty bearings with either a replica or redesigned part.
Boeing assumed the role of manufacturer of record when it acquired McDonnell Douglas in 1997. The last time the UPS plane that crashed had its engine pylon inspected was in October 2021.
Some safety experts question whether Boeing should have been more definitive in its warning given the history of bearing failures going back to the DC-10, the MD-11’s predecessor, per reporting by the Associated Press.
FedEx officials have suggested they could be flying their MD-11s again by the spring, but no officials or other companies have commented about the necessary conditions and timetable for a return to service.
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Write to Eric Kulisch at ekulisch@freightwaves.com.
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