The National Transportation Safety Board on Nov. 20 released a preliminary report on the crash of a UPS MD-11 cargo jet in Louisville, Kentucky on Nov. 4. Included were a series of dramatic images of the jet bursting into flames on takeoff.

Federal investigators released a preliminary report on the deadly crash of a UPS cargo plane in Louisville, Kentucky, that killed 14 people earlier this month, revealing that hardware meant to hold one of the plane's engines in place showed signs of fatigue and "overstress failure."

The report, released on Nov. 20 by the National Transportation Safety Board (NTSB), said investigators "found evidence of fatigue cracks in addition to areas of overstress failure" on a fitting that connected the plane's left engine to the wing.

The hardware last underwent an inspection in October 2021, and it wasn't due for its next inspection for another 7,000 flights, according to investigators. The report does not say what might have led to the hardware corrosion.

UPS Flight 2976 was taking off from Louisville Muhammad Ali International Airport on Nov. 4 when it erupted into a ball of fire and crashed into an industrial area beyond the runway.

The incident killed 14 people, including three crew members, and injured an additional 23 people. It was the deadliest air disaster in UPS history.

The crash led federal authorities to temporarily ground all McDonnell Douglas MD-11 planes, as well as an additional nine plane models similar to the MD-11.

The report revealed that the decades-old plane was flown by experienced pilots and had met several inspection requirements related to its left engine mount.

The NTSB will provide a probable cause and issue safety recommendations in its final report, which could take more than a year to complete, the agency has said.

"We continue to grieve for the lives lost in the tragic accident involving Flight 2976," UPS said in a statement on Nov. 20, adding, "We appreciate the National Transportation Safety Board’s prompt release of preliminary findings and will fully support the investigation through its conclusion."

UPS crew was experienced with MD-11, report says

The NTSB investigation found that the UPS Airlines crew members aboard the plane were familiar the MD-11.

Captain Richard Wartenberg, who was monitoring the flight, was certified to fly an MD-11 and had "accumulated about 8,613 total hours of flight experience as reported to the FAA." Of those hours, 4,918 hours were in an MD-11.

First Officer Lee Truitt, the pilot determined to be flying the plane, had nearly 1,000 hours of flight experience in an MD-11, according to the report.

The relief officer, Captain Dana Diamond, was the most experienced pilot in the crew with about 15,250 total hours of flight experience reported to the FAA, with 8,775 hours in the MD-11.

UPS crash shares similarities to 1979 crash in Chicago

Investigators in the report drew comparisons between the crash in Louisville and the 1979 DC-10 crash in Chicago that killed nearly 300 people after the left pylon, which supported the engine, came loose and took out a hydraulic line.

The 1979 crash saw the left engine and pylon and part of the "leading edge" of the left wing separate from the airplane and fall to the runway, eventually leading the plane to crash into an open field.

An investigation by the NTSB into the 1979 DC-10 crash found that human error from maintenance personnel was likely a contributing factor to the fatal crash.

The NTSB investigation into the UPS plane crash is ongoing.

(This story has been updated to add new information.)

Contributing: Olivia Evans and Matthew Glowicki, Louisville Courier Journal

This article originally appeared on USA TODAY: Investigators release dramatic images of UPS cargo plane erupting into flames

Reporting by Christopher Cann, USA TODAY / USA TODAY

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