Flight History
On January 8, 2022, an Air Tractor AT301, registration HK-4615, was operating a special aerial work flight for agricultural spraying. The aircraft departed from Los Almendros airstrip (SQOA) at 09:24 local time for its sixth sortie of the day, heading to a banana plantation at Finca Lejanía, approximately 2.5 nautical miles west-southwest of Antonio Roldan Betancourt Airport. The flight was conducted under visual meteorological conditions.
Accident Sequence
About one minute after takeoff, while turning right, the pilot experienced a strong vibration and observed white smoke emanating from the engine. Simultaneously, the engine lost power, causing the aircraft to lose speed and altitude. The pilot selected a banana field for an emergency landing. Unable to clear a medium-voltage power line crossing the field at 14 feet (4.3 meters) above ground, the pilot decided to fly beneath the wires. At that moment, the engine stopped completely. The pilot maintained control and a safe airspeed until touchdown in the banana field. During the deceleration, the aircraft struck multiple obstacles before coming to rest. The pilot evacuated the cockpit through the right side unaided, sustaining minor injuries.
Aircraft and Engine Information
The aircraft was an Air Tractor AT301, configured for agricultural spraying. It was powered by a Pratt & Whitney radial engine. The investigation focused on the engine's master rod fracture.
Investigation Findings
The Colombian accident investigation authority (DIACC) determined that the accident resulted from an engine failure caused by a fracture of the master rod. The probable cause was stated as: "Engine failure originated by the fracture of the master rod, which caused loss of power, preventing the aircraft from continuing flight, forcing the pilot to make a forced landing in an unprepared field."
Contributing factors identified included:
- Aging of the base material of the master rod due to periodic operation in various atmospheric conditions, leading to physical and intergranular wear.
- Premature aging of components given engine operating time, producing material fatigue from unusual combined stress concentrations.
- Possible incorrect engine operation by crews, including insufficient cooling or thermal stabilization times and operating at or above established limits.
- Lack of procedures in the operator's maintenance manual limiting the service life of internal engine components such as rods, considering the type of operation and manufacturer restrictions.
- Lack of inspection procedures and technical documentation to determine the actual service life of master rods in radial engines.
Six operational safety recommendations were issued as a result of the investigation.