Nothing in the world of aviation safety is as chilling as the frame-by-frame effect of a sequence of shots depicting the left engine of a McDonnell Douglas MD-11F flying off her wing, arcing in front of the fuselage, and bursting into a fireball. That terrifying dislocation on November 4, in Louisville, Kentucky, has now taken a fifteenth life Alain Rodriguez Colina, a Cuban immigrant and scrapyard worker, died of severe burns on Christmas Day.
The initial investigation of the National Transportation Safety Board has indicated that the reason was fatigue cracks in the aft mount lugs of the pylon, which are structural fittings that hold the engine to the wing. Such lugs, as well as a spherical bearing between the aft mount and the wing exhibited fatigue failures and overstress failures. The wing mounted engines of the MD-11 are mounted on pylons with forward and aft bulkheads, threat link assemblies and spherical bearings, which are all designed to absorb loads exerted on the engine onto the wing structure. The imbalance that occurs due to the damaged load paths may surpass the capability of the aircraft to ensure controlled flight as it occurred in this case when the freighter did not manage to clear the 30 feet mark before hitting the ground.
The plane in question was 34 years old and was initially scheduled to serve Thai Airways in the early 1990s before it was turned into a cargo plane 20 years ago. It had recorded some 92,992 hours of flight and 21,043 cycles. Maintenance records indicate that the left pylon aft mount had not been visually inspected since October 2021, and that thrust links and spherical bearings were last lubricated on October 18, 2025. Thousands more cycles would not see a closer examination of the malfunctioning piece, and this is one of the ongoing problems with aircraft maintenance in the aging aircraft, cracks can extend long before the due dates.
The pylon design of the MD-11 has the same lineage as the DC-10, a design which has experienced the same failures, the most notorious of which was the crash of the American Airlines Flight 191 in 1979. In the two examples, the loss of aerodynamic and control during takeoff as a result of the separation of the engine and pylon assembly was not recoverable. Although the accident of the DC-10 was attributed to improper maintenance, the situation with the UPS crash does not show any signs of external damage only stating that structural fatigue has taken place and it might be enhanced by corrosion or other environmental conditions over decades of service.
More than 38,000 gallons of jet fuel loaded in the plane that were to be used in the Hawaii flight were used to fuel the fireball that engulfed Colina and others. The explosions of the aviation fuel produce high levels of radiant heat and convection currents; under enclosed or factory conditions, this may result in severe burns very fast over vast parts of the body. Colina was severely burnt, and his body was more than 50% burned which is highly fatal because of the fluid loss, the possibility of catching infections, and the systemic shock. First hand accounts of scramble to drag survivors out of the rubble as the flames swept over the petroleum recycling plant and scrapyard.
There are increasing legal consequences. Previous litigations claim that UPS had been flying older aircrafts without raising the inspection rate of those aircrafts though the average age of the fleet was over 30 years. Plaintiffs claim that cracks of this nature should have been observed considering that there was a massive maintenance done on the structures recently in San Antonio, which is known to have dealt with the other structural problems but failed to detect the pylon problems. There are also names of General Electric, Boeing, and VT San Antonio Aerospace, accused of design, manufacturing and inspection failures. In the case of over 90 victims, Masten Childers III, the lawyer representing the victims, said, “The death of Alain’s passing must be honored by holding those responsible for his death accountable.”
Federal Aviation Administration has suspended all MD-11s broadening the directive to encompass DC-10s with similar pylon outfitting. As type certificate holder, Boeing is working on inspection and corrective action procedures to be approved by FAA. UPS has 26 MD-11s (approximately 9% of its fleet), and has put in place contingency plans to sustain cargo operations by other carriers and using ground transport. According to sources in the industry, the level of inspections will be “highly invasive,” as well as the possible part replacements may take months before they are completed.
To aviation engineers and safety regulators, the crash highlights the importance of the damage tolerance in design and the constraints of fixed-interval inspection regimes. Cracks in fatigue, especially those in high load structural interfaces such as engine mounts, may progress in an unpredictable manner and, in combination with aging metallurgy and potential corrosion, require careful non-destructive testing. With the NTSB in its investigation, the engineering fraternity is keenly observing any recommendation that might redefine the maintenance standards of old cargo planes in the world.
