Flight Details
On December 9, 2023, an Air Tractor AT-301, registration HK4952, was scheduled for agricultural spraying operations in the Zona Bananera area of Magdalena, Colombia. The aircraft was operating from La Lucha airstrip (9LD) in Ciénaga. The pilot, a 53-year-old commercial pilot with extensive experience, arrived at 05:00 local time for preflight briefing. After a normal preflight inspection at 05:40, the aircraft was fueled with 50 gallons of fuel and loaded with 260 gallons of chemical product. Taxi and run-up checks were uneventful, and departure from runway 14 occurred at 06:08 local time.
Accident Sequence
The flight proceeded to a plantation located about 5 nautical miles southwest of Orihueca. Spraying began at 06:18. During the third pass, approximately at 06:25, the pilot noticed a smell of burnt oil but engine parameters were normal. He climbed to investigate. Shortly after, oil pressure dropped, the chip detector warning illuminated, and engine temperature increased. The pilot declared a MAYDAY on the company frequency and attempted to divert to Orihueca airstrip (ORH). He observed oil leakage from the right side of the aircraft and strong engine vibrations. Realizing he would not reach the intended runway, he jettisoned the chemical load and executed a forced landing in a visible field. The aircraft struck a banana plantation, causing substantial damage. The pilot evacuated the aircraft unaided and was uninjured. The accident occurred at 06:30 local time in daylight and visual meteorological conditions.
Aircraft Damage
The aircraft sustained substantial damage: the ventral section (spray pump) was affected, both wing leading edges were significantly damaged, the left main landing gear separated, and the propeller stopped abruptly. Approximately 171 square meters of banana crop were damaged.
Investigation Findings
The Colombian accident investigation authority (DIACC) determined that the forced landing was necessitated by an in-flight engine failure. The powerplant, a Pratt & Whitney R-1340 radial engine, suffered an obstruction of lubrication lines to the crankshaft and master rod section, leading to excessive friction, high temperatures, and seizure of all connecting rods. Additionally, a gradual oil leak in flight was likely caused by degraded lubrication lines for the cylinder valves. The pilot's decision to land in an unprepared field was correct given the circumstances. No post-impact fire occurred.
Probable Cause
The accident was caused by the pilot executing a forced landing in an unprepared field due to an in-flight engine failure. That failure resulted from obstruction of the crankshaft and master rod lubrication lines, causing excessive friction and overheating, leading to component seizure and separation of all connecting rods. Contributing was a gradual oil leak, possibly from degraded cylinder valve lubrication lines.