What happened
On January 17, 2025, a Grumman G-164B, registration CX-BSS-R, was conducting a pilot transition flight near Río Branco, Uruguay. The pilot, who was performing his first flight in this specific aircraft type, had previously spent the morning conducting aerial firefighting simulations in an Embraer Ipanema.
After completing a pre-flight inspection and taking off from the owner's airfield, the aircraft maintained a stable flight at approximately 2,000 feet for about 25 minutes. During the flight, the pilot experienced engine explosions followed by a sudden loss of power. The pilot initiated a controlled descent to maintain airspeed and prepared for an emergency landing in a nearby pasture.
Upon impacting the ground, the aircraft struck several large termite mounds (known locally as *tacurúes*). The force of the impact caused the main landing gear to collapse and the aircraft to capsize, eventually coming to rest in an inverted position. The pilot was able to exit the aircraft uninjured.
The investigation
The CIAIA conducted a technical investigation, which included a teardown of the Pratt & Whitney R985-AN14B engine at the owner's hangar. Investigators examined the magnetos, air and fuel filters, and checked for metal particles in the oil. No mechanical failures were found; the magnetos functioned normally, and there was no evidence of internal engine damage or compression issues.
Investigators also compared the cockpit configurations of the two aircraft the pilot had operated that day. The Embraer Ipanable utilized a three-lever system (power, propeller pitch, and mixture) with a specific layout, whereas the Grumman G-164B utilized a different two-lever arrangement. The physical similarity of the levers between the two different aircraft types was noted during the analysis.
Findings
- The primary contributing factor was pilot confusion regarding engine controls due to the different configurations of the aircraft operated on the same day.
- The pilot was performing a transition flight, marking his first time operating the Grumman G-164B.
- The presence of large termite mounds (*tacurúes*) in the landing site significantly contributed to the aircraft's capsize and substantial structural damage.
- The engine and flight controls showed no evidence of mechanical malfunction prior to the power loss.