Fatal Structural Failure of a YPF Company Aircraft Near Cutral Có (LV-HHB)

Incident Overview and Flight Details On the day of the accident, the aircraft departed Rincón de Los Sauces Airport at 1555 local time, bound for Cutral Có. The flight was carrying 31 employees of the Yacimientos Petroliferos Fiscales Company. During the descent toward Cutral Có, the crew communicated with air traffic control, providing an estimated time of arrival of 1633 local time and requesting a final weather briefing for the destination airport. ## Accident Sequence Less than two minutes after the communication with air traffic control, the aircraft was flying at an altitude of 4,000 feet when the right wing detached and separated from the fuselage. The aircraft subsequently lost control, entered a dive, and crashed 35 kilometers north of Cutral Có. The impact resulted in the total destruction of the aircraft, and all 34 occupants on board were killed. ## Official Probable Cause The official investigation determined that the accident was the result of the detachment of the right wing during normal flight. This occurred due to a structural failure in the wing area between stringers 3 and 12 and in the area of the engine outer rib. The investigation identified fatigue origins within this area, specifically pointing to a reinforcing plate and the holes in it for rivets. Because the material itself was satisfactory, the fatigue cracks were attributed to stress concentration caused by the geometry of the design, which caused the cracks to become critical sooner than estimated. The cracks remained undetected and reached a critical state because the manufacturer's inspection program for the area was insufficiently precise, preventing the operator from detecting and correcting them in time.