NTSB preliminary report cites left pylon cracks in UPS MD-11F crash

The U.S. National Transportation Safety Board (NTSB) has issued its preliminary report on the November 4 crash of UPS flight 2976, an MD-11F operating a scheduled service from Louisville Muhammad Ali International Airport to Honolulu’s Daniel K. Inouye International Airport.

The 12-page report states that the airplane, registered N259UP, was destroyed after impacting the ground shortly after departing runway 17R at Louisville Muhammad Ali International Airport (SDF) in Kentucky. All three crew members on board and 11 people on the ground were fatally injured, while 23 others on the ground sustained injuries.

The report mentions that the taxi and takeoff roll were uneventful until the airplane rotated for takeoff. Airport surveillance video of the airplane showed the left (No. 1) engine and pylon separating from the wing shortly after airplane rotation, with a fire igniting on the left engine while it traversed above the fuselage and subsequently impacted the ground. A fire ignited near the area of the left pylon attachment to the wing, which continued until ground impact.

The airplane initially climbed but did not get higher than about 30 ft above ground level (agl) according to radio altitude data from the FDR (Flight Data Recorder). (Based on Federal Aviation Administration (FAA)-provided ADS-B data, the last data point showed 481 ft mean sea level [msl] and 100 ft agl.)

The airplane cleared the blast fence beyond the end of runway 17R, but the left main landing gear impacted the roof of a UPS Supply Chain Solutions warehouse at the southern edge of the airport. The airplane then impacted a storage yard and two additional buildings, including a petroleum recycling facility, and was mostly consumed by fire.

After initial cleaning of the fracture surfaces, examination of the left pylon aft mount lug fractures found evidence of fatigue cracks in addition to areas of overstress failure. On the aft lug, on both the inboard and outboard fracture surfaces, a fatigue crack was observed where the aft lug bore met the aft lug forward face.

For the forward lug's inboard fracture surface, fatigue cracks were observed along the lug bore. For the forward lug’s outboard fracture surface, the fracture consisted entirely of overstress with no indications of fatigue cracking. The forward top flange of the aft mount assembly was examined for indications of deformation or pre-existing fractures, but no indications were found. The spherical bearing was removed from the wing clevis for further evaluation.

All the pilots, including the Captain, First Officer, and Relief Officer (RO), held transport pilot certificates and a type rating for the MD-11. The Captain had accumulated approximately 8,613 total flight hours, of which 4,918 were on the accident airplane’s make and model, as reported to the FAA.

The airplane was equipped with an FDR and a Cockpit Voice Recorder (CVR), both of which were recovered from the accident scene and transported to the NTSB Vehicle Recorders Laboratory in Washington, DC. Data from both the CVR and FDR were successfully downloaded. The NTSB convened separate CVR and FDR groups, composed of qualified party members, to transcribe the accident flight recording from the CVR and to validate the flight data from the FDR, respectively.

On November 7, UPS grounded its entire MD-11 fleet following Boeing’s recommendation. The FAA issued an Emergency Airworthiness Directive (AD) requiring inspections and any necessary corrective actions on all MD-11 and MD-11F airplanes before further operation.