What happened
On February 8, 2012, a Neiva EMB-202A aircraft, registration PT-UUJ, was performing agricultural spraying operations over a sugarcane plantation at Fazenda Harmonia, near Sonora, Mato Grosso. The aircraft had departed from Fazenda Sonora (SSUA) to apply insecticide.
As the pilot descended to the application altitude, an abnormal noise was heard from the engine, immediately followed by a loss of power. In an attempt to maintain control, the pilot applied maximum power and jettisoned the liquid load from the hopper. Despite these actions, the landing gear became entangled in the sugarcane foliage, leading to a ground impact. The aircraft sustained substantial damage, but the pilot escaped the wreckage uninjured.
The investigation
CENIPA investigators examined the engine components and the fuel used during the flight. The aircraft's documentation, including the airworthiness certificate and maintenance logs, were found to be up to date. The aircraft was within weight and balance limits, and the pilot was fully qualified with valid medical and agricultural ratings.
Laboratory analysis of the fuel conducted by the National Agency of Petroleum, Natural Gas and Biofuels (ANP) confirmed that the fuel met all required specifications. However, a detailed examination of the engine revealed severe mechanical degradation. Investigators found significant wear on one of the camshaft lobes, which had reduced in height from 100mm to 50mm, along with surface deformation and material loss on two tappet covers.
Analysis by the Department of Science and Technology of the Air Force (DCTCA) identified the presence of pitting and spalling on the camshaft and tappet surfaces. The investigation noted that because the engine operated on ethanol, it was subject to higher risks of corrosion due to the higher water content in ethanol compared to Avgas. The findings suggested that inadequate lubrication or the accumulation of moisture from ethanol evaporation could lead to the fatigue cracks and material loss observed.
Findings
- Engine component failure due to extreme wear on a camshaft lobe and damage to two tappet covers.
- The presence of pitting and spalling caused by high contact stress and repetitive cycles.
- Potential contribution of corrosion or inadequate lubrication, exacerbated by the use of ethanol as fuel.
- The landing gear's interaction with the sugarcane crop during the descent led to the final impact.