What happened
On April 21, 2018, a Neiva EMB-201A, registration PP-EOQ, was performing a ferry flight from Santo Antônio do Leverger to Tangará da Serra, Mato Grosso. Approximately ten minutes after takeoff, while the aircraft was in its climb phase, the pilot experienced a significant loss of engine power accompanied by rising temperatures and a drop in oil pressure.
To avoid a more serious accident, the pilot executed an emergency landing on a section of the BR-070 highway near Nossa Senhora do Livramento. After clearing the roadway, the aircraft came to rest on a nearby dirt road. The pilot was uninjured, and the aircraft sustained light damage.
The investigation
CENIPA investigators examined the Lycoming IO-540-K1J5D engine and the aircraft's maintenance records. While the propeller governor, magnetos, and fuel system were functioning correctly, the investigation uncovered several irregularities in the engine's maintenance history. The aircraft's logbooks contained erasures and unrecorded entries, and there was no official record of a previous engine overhaul that had clearly taken place.
Technical analysis of the engine revealed significant internal issues. Investigators found that the engine oil pump had been reused and showed signs of internal wear. Furthermore, the investigation identified cracks in the spark plug housings of cylinders 3 and 4. In cylinder 5, a bushing had been installed in the lower spark plug housing in a manner that deviated from the manufacturer's specifications. This improper installation caused combustion gas leaks and prevented effective heat dissipation.
Findings
- The engine experienced a loss of power due to excessive operating temperatures caused by mechanical discrepancies.
- Cracks were present in the spark plug housings of cylinders 3 and 4.
- An unauthorized bushing was installed in the cylinder 5 spark plug housing, leading to carbon buildup and heat retention.
- The piston in cylinder 4 showed signs of overheating and the onset of seizure.
- Improper maintenance practices and inadequate maintenance supervision contributed to the engine's failure.
- Maintenance records for the airframe and engine were inconsistent and lacked proper documentation for certain interventions.