A tragic incident involving a UPS cargo plane that erupted into flames, resulting in the deaths of 14 individuals in Louisville, Kentucky, has been attributed to what investigators describe as ‘metal fatigue.’

The 34-year-old McDonnell Douglas MD-11 aircraft exhibited structural cracks in the components connecting its left engine, as detailed in a preliminary report released by authorities on Thursday.

According to the report, investigators uncovered ‘evidence of fatigue cracks along with sections showing overstress failure’ within the engine mount.

While accelerating along the runway at Louisville Muhammad Ali International Airport on November 4, en route to Hawaii, the General Electric engine detached from the aircraft’s left pylon, which links the engine to the wing.

As the engine soared over the fuselage and subsequently hit the ground, it ignited a fire.

Another fire ignited near the left pylon attachment, continuing to blaze until the plane crashed, claiming the lives of all three crew members and 11 individuals on the ground, while injuring 23 others.

Shocking photos released along with the preliminary report show flames emerging just moments after the engine detached, suggesting the fire may have been a result of the detached engine striking a fuel-filled plane.

Despite the inferno consuming the left side of the cargo plane, the aircraft was able to clear the airport’s fence – but it never made it more than 30 feet above the ground, the report stated. 

Shocking photos released on Thursday show flames emerging from the UPS cargo plane that crashed in Louisville, Kentucky just moments after the engine detached

A fire ignited as the engine fell to the ground, and another blaze also started near the left pylon attachment, which continued to burn until the plane crashed

One witness in the Air Traffic Control tower at the time told investigators the plane seemed to be going at the proper speed for takeoff but was unable to climb properly, the report said.

Another witness said the plane stopped climbing, lost altitude and then rolled ‘slightly to the left.’

When it then crashed down, the plane made impact with ‘a storage yard and two additional buildings, including a petroleum recycling facility, and was mostly consumed by fire.’

It is unclear when the cracks may have developed, but the NTSB noted UPS last inspected the engine mount in question in 2021.

It was not due for another inspection until the plane completed another 7,000 flights. 

The left pylon was also visually inspected by a UPS maintenance crew on October 28, just seven days before the fatal crash. 

‘It appears UPS was conducting this maintenance within the required time frame, but I’m sure the FAA is now going to ponder whether that time frame is adequate,’ former federal crash investigator Jeff Guzzetti told The Associated Press.

All three crew members on the plane perished as did 11 others on the ground

Community members are pictured signing placards placed on crosses at a vigil for those killed in the devastating crash on November 7

It therefore remains unclear when the cracks may have started to develop and whether they could have been missed in the earlier inspection.

John Cox, another aviation expert, described fatigue cracks as ‘normal wear and tear on an aircraft.’

He said a metal part, like the engine mount that vibrates every time the plane flies, will eventually develop cracks. Cox noted it’s just a question of how often those parts need to be inspected and what maintenance is required.

But attorney Robert Clifford told the Louisville Courier Journal the NTSB’s findings suggest the aircraft was ‘old, tired and well beyond its useful life.’

‘Metal fatigue can happen over time and should be detected upon proper safety investigations and inspections,’ said Clifford, who has represented families in commercial airline crashes for 45 years and has been retained by victims of the UPS crash.

‘The failure to properly detect the fatigue fractures could easily be the reason why there was an ultimate failure of the pylon used to attach the engine to the wing.’

In a statement to the Courier Journal on Thursday, UPS said it continues ‘to grieve for the lives lost in the tragic accident involving Flight 2976.’

The company noted that it ‘proactively grounded its MD-11 fleet out of an abundance of caution’ following the deadly crash.

‘We appreciate the National Transportation Safety Board’s prompt release of preliminary findings and will fully support the investigation through its conclusion,’ it added.

A final report is expected about one year after the accident.

MD-11 aircraft make up about nine percent of the UPS fleet and four percent of the FedEx fleet

The NTSB’s report on Thursday revealed the first new details about the deadly crash since board member Todd Inman briefed reporters on November 7, when he announced that the cockpit voice recorder captured an alarm bell going off about 37 seconds after the UPS crew called for takeoff thrust.

Following the crash, the Federal Aviation Administration issued an Emergency Airworthiness Directive to the owners and operators of the MD-11, which ‘determined the unsafe condition [the UPS plane faced] is likely to exist or develop in other products of the same type design.’

It then grounded all of the planes until they could be individually inspected and repaired.

The directive was then extended to include nine additional models of similar planes on November 14. 

It is unclear what repairs may be needed, and Bill Moore, president of UPS Airlines, has said returning the MD-11 fleet to service is ‘not going to happen quickly.’ 

MD-11 aircraft make up about nine percent of the UPS fleet and four percent  of the FedEx fleet, the companies have said. 

Cox said those air carriers ‘are going to have to make some hard decisions’ because they were already planning to retire the planes in the next few years.

‘If you have to pull the engines off and do some sort of visual inspection or replacement, that´s going to run into a significant cost,’ he said.

The NTSB’s report on Thursday revealed the first new details about the deadly crash since November 7. Members of Kentucky National Guard 41st Civil Support Team are pictured using a portable gas chromatograph mass spectrometer to test for airborne toxic chemicals

A member of the US Air National Guard is seen surveying the horrible damage left behind from the crash on November 5 

The NTSB report noted the similarities between the UPS crash and one in Chicago in 1979 involving an American Airlines DC-10 plane, the predecessor of the MD-11.

‘The left engine and pylon assembly and about three feet of the leading edge of the left wing separated from the airplane and fell to the runway,’ the report said of the crash that killed 273 people. 

But Guzzetti said there were different circumstances leading up to that crash and the one earlier this month. 

An ensuing investigation of the 1979 crash found other DC-10s with structural damage in cases where shops had serviced the engine pylons using a forklift and damaged key parts during maintenance.

In this case, however, the NTSB found no ‘indications of deformation or pre-existing fractures’ that would suggest the pylon sustained damage while it was under maintenance for more than a month in San Antonio, Guzzetti told the Wall Street Journal.

Former federal crash investigator Alan Diehl said he now hopes the FAA reevaluates plane maintenance schedules and considers high-tech methods to examine metal, not just visual inspections.

‘It is clear that engine pylon attachment failures are these aircraft´s Achilles’ heels,’ Diehl said.

The MD-11 and the DC-10 have some of the highest accident rates of any commercial planes, according to statistics published annually by Boeing, but unlike the MD-11s, the DC-10s are no longer in commercial use.