What happened
On September 9, 2025, a Boeing 777-222(ER), registered as N796UA and operated by United Airlines, departed from Ministro Pistarini International Airport (Ezeiza) bound for Houston, Texas. The aircraft was performing a scheduled commercial passenger service.
Approximately 35 minutes into the flight, while cruising at 28,0-feet, the crew received an alert from the Engine Indication and Crew Alerting System (EICAS) indicating low hydraulic fluid levels in the center hydraulic system. Shortly thereafter, the system reported low pressure within the same hydraulic circuit. In response to these indications, the crew declared an emergency and initiated a return to the departure airport.
Following established non-normal checklists, the crew performed an in-flight fuel burn to reduce the aircraft's weight to within maximum landing limits. The aircraft landed safely at Ezeiza approximately one hour and 45 minutes after its initial takeoff.
The investigation
Following the emergency landing, the crew notified United Airlines. In accordance with manufacturer technical guidelines, maintenance personnel stationed at Ezeiza performed a detailed inspection of the aircraft. The investigation established that the hydraulic fluid loss was caused by a leak originating from a hydraulic fuse located in the right landing gear compartment.
Maintenance crews replaced the faulty hydraulic fuse and verified the integrity of the system. After the repair was completed and functionality was confirmed, the aircraft was returned to service and resumed its scheduled flight to Houston on September 11.