What happened
On January 17, 2011, an EMB-201 aircraft, registration PT-GHP, was performing an agricultural spraying mission over a rice plantation at Fazenda Porteira Velha in Mostardas, Rio Grande do Sul. Approximately two minutes after departing from the farm's runway, the aircraft's left wing detached during flight. This structural failure caused the pilot to lose control, resulting in a nose-first impact with the ground. The pilot was killed in the accident, and the aircraft was destroyed.
The investigation
CENIPA's investigation focused on the structural integrity of the aircraft and the maintenance practices of the operator, Mostardas Aviação Agrícola Ltda. Investigators examined the wreckage and discovered that the left wing had separated due to a fracture in the front spar. The investigation revealed that the aircraft had a history of significant downtime and previous accidents, including an eight-year period without use following a prior incident.
Technical analysis of the wreckage showed that maintenance performed on the left wing did not comply with the manufacturer's specifications. Specifically, the investigation identified corrosion cavities within the spar bolt holes that had progressed into a fatigue condition, eventually leading to the structural failure. Furthermore, there was no documented evidence of a certified engineer releasing the aircraft for flight following its previous repairs.
Findings
- The structural failure of the left wing was caused by a fracture in the front spar.
- The fracture originated from corrosion cavities in the spar wall that evolved into fatigue cracks.
- Maintenance procedures performed on the left wing were non-compliant with the manufacturer's manual.
- Organizational deficiencies within the company contributed to the accident, including a lack of adequate maintenance supervision and a culture where maintenance tasks were performed in disagreement with technical manuals.
- Communication breakdowns between company administration and employees regarding maintenance expenditures and operational requirements hindered safety oversight.
- The accumulation of duties, where a company partner acted as both a mechanic and a pilot, compromised the quality of maintenance supervision.