Summary
On 22 June 2023, at 10:32 local time, a Cessna A188B AG Truck, registration HK-1971, was conducting agricultural spraying operations from its base at Pista Natalia (SQTZ) in Puerto López, Meta, Colombia. During the final low-altitude pass over a rice field, the engine lost power. The pilot selected an adjacent open field for an emergency landing.
Event Details
The pilot had performed two pre-flight checks earlier that morning, including two circuit flights, both with normal engine parameters. The aircraft was loaded with 30 gallons of fuel and 130 gallons of agrochemical product. Due to morning weather conditions, the flight departed at 10:12 HL. During the spraying run, engine parameters were normal with oil pressure at 45 PSI, slightly low but within limits. On the final pass, the engine lost power. The pilot chose an unprepared field with no crops. On final approach, the aircraft passed between two young trees, causing the wingtip fairings to contact thin branches, but control was maintained. The pilot executed a controlled landing on the main landing gear with flaps extended and tail up. After touchdown, the wheels sank into soft soil, causing the nose to pitch forward and the propeller to strike the ground. The aircraft then nosed over and came to rest inverted. The pilot was uninjured and exited the aircraft with help from local residents. The accident occurred in daylight with visual meteorological conditions.
Aircraft and Engine Examination
The aircraft sustained substantial damage. The main structure was inverted. The propeller blades were deformed from ground impact. The left wing had leading-edge deformation from tree contact; the right wing's leading edge was partially separated from the structure, and the right wingtip fairing detached. The engine cowling was fractured and deformed on the left side. The aircraft was examined at the accident site and later the engine was disassembled at an authorized facility. Inspection revealed that the No. 1 and No. 2 crankshaft main bearings were fractured and displaced from their seats. Additionally, the rocker arm support bolt of cylinder No. 6 was found fractured. These conditions limited engine lubrication and caused vibrations, leading to unrecoverable power loss.
Investigation and Probable Cause
The Colombian accident investigation authority (DIACC) was notified and assigned investigators. The NTSB was also notified as the state of design and manufacture. The investigation determined the probable cause as: emergency landing in an unprepared field due to engine power loss. A contributing factor was the fracture of the cylinder No. 6 rocker arm shaft bolt, causing engine vibrations, and the fracture and displacement of bearings No. 1 and 2, which limited lubrication and led to engine failure.