The National Transportation Safety Board released its preliminary report on the fatal UPS plane crash that killed 14 people and injured 23 on Nov. 4. Investigators state that the plane’s left engine ripped off the wing just after takeoff, causing the plane to roll to the left before slamming into the ground.
Included in the report were dozens of images of debris and a timeline of the moment the engine detached from the plane. The crash prompted the Federal Aviation Administration to ground all MD-11 aircraft so engineers could inspect each plane individually.
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What did the report find?
Investigators say the plane’s No. 1 engine and its pylon, or the structure that connects the engine to the wing, sustained structural damage. The damage caused the structure to fail and the engine to separate from the aircraft.
A timeline photo of the incident shows the plane taking off as the engine separates, arcs over the plane and catches fire before hitting the ground. The final photo shows the plane, now with the engine missing, starting to roll to the left.
The report states that a second fire started at the pylon-wing attachment point after the engine separated from the plane.
Flight data recovered from the wreck showed that the plane never climbed higher than about 30 feet above ground level but did clear the runway’s blast fence. Shortly after clearing the fence, the plane’s left landing gear struck the roof of a UPS warehouse before colliding with a storage yard and multiple buildings. One of these buildings was a petroleum recycling facility that ignited and engulfed the plane.
Several critical components showed signs of fatigue damage, according to the report. The left pylon aft mount’s forward and aft lugs were both fractured, and investigators found fatigue cracking on multiple fracture surfaces. They said these cracks existed before the engine separated.
Because of the similar design of the engine mount, the FAA issued a second airworthiness directive for the DC-10 series aircraft.
Despite these cracks, the report states that the plane never missed a required maintenance inspection. It also doesn’t say if engineers reported problems with the aircraft. The plane had just had a 24-month/4,800-hour lubrication maintenance check for its thrust links and spherical bearings on Oct. 18.
Investigators cite similar incident
In their report, investigators explicitly cited the American Airlines flight 191 disaster, which remains the deadliest aviation incident in American history. The two events had a strikingly similar chain of events, with both aircraft losing their No. 1 engine and pylon on takeoff.
The American Airlines flight happened in Chicago in 1979 and killed all 271 people on board the plane and two people on the ground. The NTSB determined the engine on flight 191 had separated because of “damage caused by improper maintenance procedures.” They said this led to the failure of the pylon structure.
Investigators did not confirm if that was the reason for this separation. They stressed that the investigation is ongoing.
