What happened
On March 30, 2001, a PIPER PA-36-285, registration EC-ERI, was performing agricultural spraying operations near El Judío, Córdoba. During the tenth and final flight of the day, the aircraft departed from a temporary dirt runway and initiated a right-hand turn. During this maneuver, the aircraft experienced a sudden descent. In an attempt to recover altitude, the pilot performed an emergency release of the chemical payload.
Following the release of the load, the aircraft's nose pitched up significantly. This maneuver caused the aircraft to enter a stall, leading it to plunge into the ground. The aircraft struck the terrain with its right wing first, followed by the lower fuselage. The pilot survived the impact without injury.
The investigation
The investigation examined the aircraft's configuration, weight and balance, and the flight conditions at the time of the accident. The aircraft had previously undergone a re-motorization, replacing the original 285 HP engine with a more powerful 375 HP LYCOMING IO-720-DICD engine. While this increased the engine's capability, the official maximum takeoff weight (MTOW) documentation had not been updated to reflect the higher performance potential.
Investigators also analyzed the payload. The pilot had loaded the hopper to use the remaining fumigant, which was approximately 800 liters. However, due to the aircraft not being perfectly level during loading, the actual amount may have been higher, potentially reaching 900 liters. Calculations indicated that the aircraft's takeoff weight exceeded its approved maximum by approximately 75 kg (165 lbs).
Findings
- The primary cause of the accident was an aerodynamic stall caused by an excessive increase in the angle of attack following the emergency load release.
- The aircraft was operating significantly above its approved maximum takeoff weight.
- The aircraft was experiencing a tailwind component during the right-hand turn due to the prevailing westerly winds.
- The sudden reduction in weight from the emergency discharge caused the nose to pitch up, which the pilot failed to counteract with sufficient downward elevator input and power management.