What happened
On January 31, 2021, a Cessna T188C, registration PT-WUU, was engaged in agricultural spraying operations at Colorado Farm in the municipality of São Félix do Xingu, Brazil. The aircraft was carrying a 500-liter mixture of adrazine and water in its hopper. After completing several spraying passes, the pilot attempted a reverse turn to reposition the aircraft for a final pass. During this upward left turn, the aircraft lost lift and altitude, impacting the ground in a nose-down attitude. The impact destroyed the aircraft and resulted in the fatal injuries of the pilot.
The investigation
CENIPA's investigation focused on the sequence of events and the technical state of the aircraft. Investigators found no evidence of engine failure, fuel system malfunction, or mechanical issues contributing to the crash, noting that the engine continued to run after the impact. However, the investigation revealed significant irregularities regarding the aircraft's maintenance and fuel usage. Evidence showed the engine had been modified to operate on ethanol without the required certification process. Furthermore, while the aircraft's airworthiness certificate (CVA) was valid, the modification to use ethanol had not been officially documented or approved by the competent authorities.
Additionally, investigators could not verify the aircraft's weight and balance status due to the absence of technical logbooks and operational documentation. There were also concerns regarding the management of fuel, as ethanol was being stored in tanks labeled for aviation kerosene (JET-A1).
Findings
- Inappropriate piloting judgment during the repositioning maneuver, which likely involved a turn so tight that it induced a stall and subsequent loss of control.
- Potential inadequacy in the use of flight controls during the recovery phase of the turn.
- Unauthorized engine modifications to allow for ethanol operation without proper regulatory approval.
- Lack of available maintenance and operational documentation to confirm weight and balance compliance.