What happened
On July 19, 2013, at approximately 07:00 local time, a Piper PA-25-260, registration HK-419, was performing agricultural spraying operations over a field in the municipality of El Guamo, Tolima. The aircraft, operated by Fumigaciones Aéreas de Colombia S.A.S (FARCA S.A.S), had successfully completed its first flight of the day.
During the second flight, while the pilot was executing a right-hand turn to return to the spraying path, the aircraft experienced a sudden loss of flight control. The pilot reported that the control stick failed to respond. In response to the emergency, the pilot activated the emergency system, jettisoned the fungicide payload, and shut down the engine to prepare for an emergency landing in a nearby cotton field. During the maneuver, the aircraft struck the terrain, resulting in severe structural damage to both wings, the engine cowling, and the propeller, as well as the separation of the main landing gear.
The investigation
The GRIAA investigation focused on the mechanical failure of the flight controls and the maintenance history of the aircraft. Investigators located a break in the left-wing aileron control cable near the rudder pedals. Physical examination of the cable revealed high levels of corrosion, fraying, and fatigue-induced strand breakage. The investigation also identified that the pulley, bolts, and pins in this area showed significant deterioration due to corrosion.
Regarding maintenance records, the investigation found several irregularities. Although a 100-hour inspection had been performed 15 days prior to the accident, the technician's signatures were missing from critical inspection items related to aileron controls. Furthermore, the inspection was conducted using an outdated version of the company's maintenance manual. The investigation also noted that the required 1,000-hour inspection had not been performed, as the aircraft had reached 1,140 flight hours.
Findings
- The primary cause of the accident was the rupture of the left aileron control cable due to corrosion and fatigue.
- The 100-hour inspection was likely incomplete or insufficiently detailed, as the technician failed to sign off on control inspections and did not detect the corroded cable.
- Maintenance documentation was poorly controlled, evidenced by the use of an outdated inspection format and missing signatures on various maintenance tasks.
- The aircraft was operating beyond its scheduled 1,000-hour inspection interval.
- The pilot was unharmed and successfully exited the aircraft following the impact.