What happened
On May 1, 2015, at approximately 17:00 UTC, an Embraer EMB-711ST Neiva, registration PT-RKA, was conducting a local flight departing from Formosa, Goiás. While cruising at 4,000 feet near Cabeceira Grande, Minas Gerais, the aircraft experienced a sudden drop in engine oil pressure, followed by a decrease in engine RPM.
In response to the engine failure, the pilot performed a forced landing on a dirt road at Fazenda Santa Matilde. Following the touchdown, the aircraft collided with native vegetation, resulting in a sudden stop and substantial damage to the airframe, wings, propeller, and landing gear. The pilot emerged from the accident uninjured.
The investigation
CENIPA investigators examined the engine components and reviewed maintenance records. Analysis of the engine revealed a fractured crankshaft and a broken number 3 piston. Laboratory testing conducted by the Department of Aerospace Science and Technology (DCTA) determined that the crankshaft failed due to fatigue, likely caused by an imbalance. The piston fracture was a secondary result of the overload caused by the crankshaft failure.
Fuel samples collected at the scene were tested and found to be within standard Avgas specifications, with no evidence of contamination. The investigation also identified significant discrepancies in maintenance documentation. Specifically, a discrepancy was found between the propeller hours recorded in a service order (129.5 hours) and those recorded in the engine logbook and component control map (99.8 hours).