What happened
On January 3, 2020, at approximately 21:15 UTC, a Neiva EMB-202A agricultural aircraft, registration PT-UTS, took off from a landing strip at Fazenda Cajú in Leme, São Paulo, to perform fertilizer application. Shortly after departure, the pilot experienced a sudden engine failure. The pilot performed an emergency landing in a cultivation area at the end of the runway. While the aircraft sustained substantial damage, the pilot emerged from the incident uninjured.
The investigation
The investigation examined the engine, fuel, and maintenance records. The pilot was found to be fully qualified with valid medical and agricultural ratings. The aircraft's airworthiness certificate was valid, and all maintenance logs for the airframe, engine, and propeller were up to date. Meteorological conditions were favorable for the flight.
Laboratory analysis of the fuel revealed that the ethanol contained in the tanks was contaminated, showing a higher specific gravity and lower alcohol content than required by technical specifications. However, investigators could not definitively determine if this contamination caused the engine malfunction. Analysis of the engine oil showed that lubricant properties were within standard parameters.
Upon disassembly of the Lycoming IO-540-K1J5 engine, investigators found that a nut on the capillary tube of cylinder number one, near the fuel distributor, was loose. This allowed fuel to leak, reducing the pressure and flow to the remaining cylinders and compromising engine performance. Additionally, the fuel injector for cylinder number one was found to be obstructed. While the obstruction was caused by agricultural chemicals penetrating the loose connection after the crash, the loose nut was the primary mechanical discrepancy identified.
Findings
- The engine failure was caused by a loose capillary tube nut on cylinder number one, which led to fuel leakage and reduced pressure/flow to the other cylinders.
- The fuel in the aircraft tanks showed signs of contamination.
- The aircraft was operating within weight and balance limits with all required documentation in order.
- The maintenance cause for the loose nut remained undetermined.