What happened
On March 1, 2008, at approximately 19:30 UTC, a Neiva EMB-202 agricultural aircraft, registration PT-UPC, took off from a private airstrip at Fazenda Leonardo in Itiquira, Mato Grosso, for a local mission involving the application of pesticides. Shortly after departure, the engine experienced a significant loss of power. To mitigate the risk, the pilot jettisoned the chemical load from the hopper and performed a forced landing in a nearby cotton field. The aircraft sustained substantial damage, but the pilot escaped the wreckage uninjured.
The investigation
CENIPA investigators examined the wreckage and conducted several technical tests to determine the cause of the power loss. Upon inspecting the propeller, investigators found that all three blades had bent backward, a deformation consistent with an impact without engine traction. While the guide pins for all three blades were found broken, investigators determined that the simultaneous breakage of all pins during flight was highly unlikely; instead, they concluded the pins likely broke upon impact with the ground.
Engine components, including the fuel pump, fuel metering unit, magnetos, and cables, were tested on a bench and were found to be functioning normally. However, the investigation revealed significant internal engine issues. Specifically, three lobes on the camshaft exhibited approximately 3.5mm of wear, affecting the intake valves of cylinders 1 and 2 and the exhaust valve of cylinder 5. Additionally, metal shavings were found in the oil filter, and irregular cylinder head edges indicated abnormal fuel combustion due to burnt material buildup.
Findings
- The engine experienced a loss of power due to camshaft lobe wear.
- The wear on the camshaft lobes likely caused a failure in the timing of the intake and exhaust valve operations.
- The presence of metal shavings in the oil filter and irregular cylinder head surfaces indicated internal engine degradation.
- The aircraft was within weight and balance limits, and the pilot was properly licensed and experienced.
- The propeller damage was a result of the impact with the terrain rather than an in-flight failure.