What happened
On October 28, 2022, at approximately 01:20 UTC, an American Airlines Boeing 777 (registration N-765AN) was performing a takeoff from Ministro Pistarini International Airport in Ezeiza, Argentina, bound for Miami. During the takeoff roll, as the aircraft approached rotation speed, fragments from the left engine's thrust reverser panel and the exhaust nozzle separated from the engine.
As the aircraft reached 120 knots, the flight crew noticed that fuel flow and Engine Pressure Ratio (EPR) indications for the left engine momentarily disappeared from the avionics displays. Simultaneously, cabin crew reported seeing sparks and hearing unusual noises emanating from the left engine. After reaching an altitude of 3,000 feet, the crew declared an emergency and executed a return to Ezeiza. The aircraft landed safely without further damage to the airframe or systems, though debris from the engine separation contaminated the runway, requiring cleanup by ground personnel.
The investigation
The investigation focused on the structural integrity of the Rolls Royce Trent 892-12 engine. Physical inspections of the left engine revealed external damage to the nacelle and engine components caused by the departing debris. Technical examinations, including borescope inspections and non-destructive testing, identified that the detached material originated from the internal wall of the thrust reverser's left sleeve. Specifically, a section of the honeycomb structure was found to be missing from the rear sector of the reverser.
Investigators also noted that a composite material seal on the high-pressure compressor's stage 3 purge port was improperly positioned, though no evidence of overheating was found. Maintenance records were reviewed, confirming that all relevant Airworthiness Directives (ADs) regarding inspections of the internal walls of this component had been complied with. The engine was subsequently transported to the operator's facilities in Tulsa, Oklahoma, for further analysis.
Findings
- The separation of components from the thrust reverser system caused external damage to the engine nacelle and nozzle.
- Delamination of the honeycomb structure was identified on the internal wall of the thrust reverser, though it could not be determined if this was the primary cause or a result of the failure.
- The flight crew followed established emergency procedures, successfully managing the return to the airport.
- The investigation could not definitively establish the root cause of the material separation, as no specific deviations in maintenance, design, or manufacturing were identified, and the operator had no similar recent history in its fleet.