What happened
On January 23, 2007, an EMB 201A agricultural aircraft, registration PT-GTS, was performing a flight over a crop area near Rincão de São Donato, in Itaqui, Rio Grande do Sul. After departing from São Borja, the pilot attempted a landing on a dirt runway located on a farm.
During the landing roll, the aircraft began to veer to the left. In an attempt to correct this directional deviation, the pilot applied the brakes abruptly. This sudden deceleration caused the aircraft's nose to dip and strike the ground, resulting in the aircraft capsizing. The aircraft slid approximately 10 meters on its back before coming to a stop in the center of the runway. The pilot sustained minor injuries, but the aircraft suffered severe damage to the engine, propeller, cockpit, empennage, and rudder.
The investigation
CENIPA investigators examined the aircraft's configuration and the pilot's actions. At the time of the accident, the aircraft's hopper (liquid compartment) was half-full, containing approximately 300 liters of liquid. While the aircraft's center of gravity (CG) was within manufacturer limits, investigators performed force calculations and determined that the sudden braking created a significant longitudinal force.
The investigation found that the momentum of the liquid in the hopper, combined with the aircraft's weight, shifted the CG excessively forward during the abrupt deceleration. Although the hopper was equipped with a "wave breaker" device, it was insufficient to prevent the liquid from surging forward. Additionally, while the aircraft manual advised using minimal braking to prevent tire and brake wear, it did not contain a specific warning regarding the risk of capsizing due to excessive braking.
Findings
- Excessive braking application: The pilot used heavy braking to correct a yaw tendency that could have been managed using the rudder.
- Center of gravity shift: The sudden deceleration caused the liquid in the partially filled hopper to surge forward, shifting the CG beyond operational limits.
- Inadequate liquid damping: The existing wave breaker in the hopper failed to mitigate the forward movement of the liquid during heavy braking.
- Lack of operational warnings: There was no specific alert regarding the risks of operating with a partially filled hopper or the danger of capsizing during heavy braking.