What happened
On June 30, 2024, a Cessna A188A, registration HK-1476, was conducting agricultural spraying operations near La Ceiba, Ciénaga, Colombia. After completing the first sector of the assigned field, the pilot began the second phase of the mission. Upon realizing the spray material was nearly depleted, the pilot initiated a climb to return to the airfield.
During this ascent, the aircraft experienced a partial loss of engine power. Although the pilot attempted to recover the engine by using the manual fuel pump, the engine suffered a total loss of power shortly thereafter. The pilot executed emergency procedures and performed a forced landing in an agricultural field. The pilot, who was the sole occupant, evacuated the aircraft without injury, though they were later treated for a minor knee contusion.
The investigation
The GRIAA investigation focused on the fuel system and flight patterns. Analysis of the aircraft's GPS data revealed that the pilot consistently performed turns in the same direction, which led to an imbalance in fuel consumption between the wings; the left wing tank was found to be empty, while the right tank still contained fuel.
Physical inspections of the fuel system revealed significant contamination. The fuel sample contained black, plastic-like particles. Investigators found residues and mold within the wing tanks and fuel lines. Furthermore, the inspection of the fuel filter showed a corroded cover and a deteriorated stem. The investigation also identified a non-standard maintenance practice where the shut-off valve had been secured with wire, rendering it inoperable from the cockpit.
Findings
- Fuel contamination consisting of plastic-like particles and organic residue (mold) caused the engine power loss.
- The aircraft's flight patterns caused an uneven fuel distribution, leaving the left tank empty.
- Maintenance deficiencies were present, including the use of improper tools for filter inspection and the use of improper securing methods for the fuel shut-off valve.
- Inadequate operational supervision regarding flight maneuvers contributed to the fuel imbalance.
Safety action
- The operator was advised to perform detailed inspections of the fuel systems and wing structures across its entire fleet.
- The operator must strengthen maintenance programs to ensure fuel tank cleanliness and establish more frequent inspection intervals.
- An operational analysis is required to define limits on maneuvers to ensure balanced fuel usage between wings.
- The aeronautical authority will disseminate the report to agricultural spraying operators to reinforce Safety Management Systems (SMS).