What happened
On September 18, 2024, a Grumman G-164B agricultural aircraft, registration CX-RBS, was performing aerial application tasks near Arroyo Blanco, Rivera. After taking off with 500 kilograms of urea in the hopper, the pilot experienced a partial loss of engine power while turning to continue the application pattern.
The pilot executed a turn to return to the temporary operational runway and performed a partial emergency discharge of the load. During the approach to the opposite runway, the aircraft made contact with the compacted earth surface but subsequently veered to the right. This excursion caused the aircraft to strike the terrain and electric fence posts used for livestock. The aircraft eventually returned to the runway surface and taxied to the end of the strip, where it came to a stop.
The investigation
The CIAIA investigation focused on the mechanical failure of the engine and the sequence of the landing. Investigators examined the Pratt & Whitney R-985-A1 radial engine and found a fracture in cylinder number 7. The inspection of the fractured component revealed no evidence of prior manufacturing defects, improper maintenance, overheating, or external impacts.
Regarding the landing, the investigation confirmed that the pilot was fully qualified and that the aircraft's maintenance records were up to date. The weather conditions at the time of the accident were favorable, with good visibility and daylight.
Findings
- The primary cause of the power loss was a material fatigue fracture in the number 7 engine cylinder.
- The investigation noted that because cylinders for this engine model are no longer manufactured, components are often overhauled and reused, which can lead to extended operational lives exceeding that of the engine assembly itself.
- The aircraft sustained significant damage, including broken propeller blades, damage to both lower wing planes, the right wing tip, and the left horizontal stabilizer due to the impact with wooden fence supports.
- The pilot was uninjured and evacuated the aircraft on his own.
- No operational, human, or environmental factors contributed to the accident.