NTSB Report *Released* UPS Cargo Crash Flight 2976

Key Concepts

• Asymmetric Drag: Uneven drag forces on an aircraft's fuselage, making control difficult.
• V1 (Decision Speed): The speed at which a takeoff must be continued, even if an engine fails.
• VR (Rotation Speed): The speed at which the pilot pulls back on the controls to lift the aircraft off the runway.
• Pylon: The structure that attaches an aircraft engine to the wing.
• Thrust Link Assembly: A component of the pylon that transmits thrust loads.
• Bulkhead: A structural partition within an aircraft.
• Lugs: Fittings on the pylon that connect to the wing.
• Spherical Bearing: A type of bearing that allows for rotational movement.
• Fatigue Cracking: Cracks that develop in a material due to repeated stress cycles.
• Overstress Failure: Failure of a material due to exceeding its load-bearing capacity.
• Flight Data Recorder (FDR): Records various flight parameters.
• Cockpit Voice Recorder (CVR): Records audio from the cockpit.
• NTSB (National Transportation Safety Board): Investigates transportation accidents.
• FAA (Federal Aviation Administration): Regulates aviation in the United States.

UPS Crash Preliminary Investigation Report Summary

This summary details the preliminary findings of the FAA investigation into the UPS crash, focusing on the catastrophic engine detachment and subsequent destruction of the MD-11F aircraft.

1. Main Topics and Key Points

The core of the investigation revolves around the separation of the left number one engine and its pylon from the wing shortly after rotation for takeoff. This event created significant asymmetric drag, severely compromising the aircraft's controllability. The report highlights that the engine did not merely fall off but blew up and detached airborne, leading to a chain of events that doomed the aircraft.

Specific Details:

• Aircraft Type: MD-11F (a sister aircraft to the DC-10).
• Fatalities: 3 crew members and 11 on the ground.
• Injuries: 23 on the ground.
• Event Timing: Engine separation occurred "shortly after rotation" and "at rotation."
• Altitude: The aircraft did not climb higher than 30 feet above ground level.
• Impact Sequence: Cleared blast fence, left main landing gear impacted a UPS supply chain warehouse roof, then impacted a storage yard and two additional buildings, including a petroleum recycling facility that caught fire.
• Fire: The fire in the area of the left pylon attachment to the wing continued as the aircraft cleared the blast fence.
• Aircraft Age: The aircraft was a 1991 model, approximately 33 years old.
• Flight Hours: The aircraft had taken off 21,000 times with 92,000 hours.
• Crew Experience:
  • Captain (Pilot Monitoring): 8,600 total flight hours, 4,900 in type.
  • First Officer (Pilot Flying): 994 hours, 92 in type.
  • Relief Officer: 15,000 hours.
  • The pilots are described as "impressive" and "skilled."

2. Important Examples and Case Studies

The report draws a parallel to a prior accident involving American Airlines Flight 191, a DC-10, where a similar engine detachment occurred. In that case, the investigation attributed the engine separation to damage to the pylon structure caused by improper maintenance procedures, specifically the use of forklifts to hold engines in place during servicing to save maintenance costs. This historical precedent suggests a potential link between maintenance practices and engine detachment.

3. Step-by-Step Processes, Methodologies, or Frameworks Explained

The investigation process involved:

• NTSB Deployment: The NTSB traveled to the accident site to document the scene.
• Party Notification: Relevant parties were informed about the special investigation.
• Information Collection: Data and evidence were collected.
• Surveillance Video Analysis: Airport surveillance video provided frame-by-frame footage of the event.
• Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR) Download: Data from these recorders was successfully downloaded, providing insights into flight parameters and cockpit audio.
• Wreckage Examination: Recovered portions of the aircraft were transferred to a secure hangar for detailed examination.
• Materials Laboratory Analysis: The NTSB materials laboratory conducted analyses of fractured components.

4. Key Arguments or Perspectives Presented

The primary argument is that the engine detachment was the root cause of the crash. The investigation explores two potential contributing factors:

• Mechanical Failure: The report details the fracture of the lugs on the pylon aft mount. Initial examination suggested "overstress" failure for the forward lugs. However, after initial clearing, evidence of fatigue cracks was found in addition to areas of overstress failure on the left pylon aft mount lug fractures. This points to the possibility of age-related material degradation.
• Maintenance Issues: The comparison to the American Airlines Flight 191 incident strongly suggests that improper maintenance procedures, potentially involving damage to the pylon structure during servicing, could be a significant factor. The transcript notes that airlines sometimes use methods to save on maintenance costs, which can inadvertently lead to structural damage.

The speaker emphasizes that while older aircraft can fly safely if well-maintained, they have a higher incident rate (approximately twice as many incidents in aircraft over 30 years old compared to younger ones) due to the increased potential for human error in maintenance.

5. Notable Quotes or Significant Statements

• "You literally see the engine blow up and detach from the aircraft, which now creates a substantial amount of asymmetric drag on this fuselage, which makes controlling this substantially more difficult." (Describing the immediate consequence of engine separation)
• "Once you commit to the takeoff, V1, we've committed. VR, rotate. They're already in rotation. They are so committed. They are going flying." (Explaining the critical decision point in takeoff)
• "The only way you're coming back in an engine fire or failure is by turning around. But good luck doing the impossible turn when you don't have any thrust. It ain't happening. You're looking for a place to crash land." (Highlighting the limited options after committing to takeoff with an engine failure)
• "The problem is if you then harm or or or u uh damage the control uh or the I should say the support beams that hold these into place, they end up falling off or disconnecting somehow." (Speculating on the cause of engine detachment based on prior incidents)
• "The left lugs were found fractured. Oh wow. the metal just fractured. This is why older aircraft can have problems because the actual metal fractures. It doesn't even necessarily have to be a maintenance issue because if you can't see the fracture, what good does it do you?" (Describing the physical evidence of failure and the challenge of detecting such issues)
• "However, some after an initial clearing of the fracture surfaces, examination of the left pylon aft mount lug uh fractures found evidence of fatigue cracks in addition to areas of overstress failure. It's age." (Pinpointing the likely cause of structural failure)

6. Technical Terms, Concepts, or Specialized Vocabulary

• Fuselage: The main body of an aircraft.
• Engine Detachment: The separation of an engine from the aircraft.
• Asymmetric Drag: Unequal drag forces on opposite sides of the aircraft, leading to yawing and loss of control.
• Rotation: The action of pitching the aircraft nose up to lift off the runway.
• Pylon Structure: The framework connecting the engine to the wing.
• Vertical Stabilizer: The vertical tail fin of an aircraft.
• Forward-mounted Bulkhead Thrust Link Assembly: A component that transmits thrust loads from the engine to the wing at the front of the pylon.
• Aft-mounted Bulkhead: A structural partition at the rear of the pylon.
• Spherical Bail Bearing: A bearing that allows for movement in multiple directions.
• Lugs: Metal fittings used for attachment.
• Fractured: Broken.
• Fatigue Cracking: Cracks that form due to repeated stress cycles.
• Overstress Failure: Failure caused by exceeding the material's strength limits.

7. Logical Connections Between Different Sections and Ideas

The summary logically progresses from the initial event (engine detachment) to the immediate consequences (loss of control, crash) and then delves into the investigation's findings regarding the cause. The connection between the current UPS crash and the historical American Airlines Flight 191 incident serves as a crucial piece of evidence, suggesting a recurring problem related to engine pylon maintenance or structural integrity. The discussion of aircraft age and its correlation with increased incident rates provides a broader context for understanding why such failures might occur in older aircraft. The detailed examination of the fractured lugs connects the physical evidence directly to the potential causes of fatigue and overstress.

8. Data, Research Findings, or Statistics Mentioned

• Incident Rate for Older Aircraft: Aircraft over 30 years old have approximately twice as many incidents as those younger than 30.
• Accident Rate: While accidents are rare (one in a million flights), the increased incident rate in older aircraft is significant.
• Aircraft Age: The UPS aircraft was approximately 33 years old.
• Flight Hours: The aircraft had 92,000 hours and 21,000 takeoffs.

9. Clear Section Headings

• Key Concepts
• UPS Crash Preliminary Investigation Report Summary
  • 1. Main Topics and Key Points
  • 2. Important Examples and Case Studies
  • 3. Step-by-Step Processes, Methodologies, or Frameworks Explained
  • 4. Key Arguments or Perspectives Presented
  • 5. Notable Quotes or Significant Statements
  • 6. Technical Terms, Concepts, or Specialized Vocabulary
  • 7. Logical Connections Between Different Sections and Ideas
  • 8. Data, Research Findings, or Statistics Mentioned
  • 9. Clear Section Headings
  • 10. Synthesis/Conclusion

10. A Brief Synthesis/Conclusion of the Main Takeaways

The preliminary investigation into the UPS crash strongly indicates that the catastrophic failure originated with the separation of the left engine and its pylon from the wing shortly after takeoff. This event, which involved the engine blowing up and detaching airborne, created insurmountable control issues. Evidence points to fractured lugs on the pylon aft mount, exhibiting both fatigue cracks and overstress failure, suggesting that age-related degradation of the aircraft's structure, combined with the stresses of takeoff, led to the detachment. The historical precedent of American Airlines Flight 191, where improper maintenance was implicated in a similar engine separation, raises concerns about potential maintenance-related factors contributing to this incident as well. The findings underscore the increased risk associated with older aircraft, highlighting the critical importance of rigorous maintenance and the potential for human error or undetected structural weaknesses to lead to devastating consequences. The loss of life and the destruction caused by this event serve as a stark reminder of the complexities and vulnerabilities within aviation safety.