What happened
On June 13, 2019, a Tecnam P2006T, registration SP-DZW, was performing a flight test for a Commercial Pilot License (CPL) evaluation. The flight began with a departure from EPBY, including a flight through the patrol zone and a landing at EPTO, where a go-around was performed. Following several circuits at EPWT, the aircraft climbed to approximately 300 ft AGL. At this altitude, the right engine experienced a sudden and violent shutdown, accompanied by the immediate stoppage of the propeller. The entire engine shutdown process lasted between 3 and 5 seconds. The examiner took control of the aircraft and executed a circuit to land at EPWT using maximum power from the remaining left engine. The landing was completed safely at 08:40 LMT without further incident.
The investigation
The PKBWL examined the engine, which was under warranty and had only 2 hours and 35 minutes of time since its last overhaul. An initial teardown performed in Poland revealed extensive internal damage, including material loss on piston number 1, seized pistons in cylinders 2 and 3, broken connecting rods, and significant metal shavings throughout the crankshaft and cylinders. The engine was subsequently sent to the manufacturer, BRP - ROTAX GmbH & Co KG, in Austria, for further analysis. While the manufacturer hypothesized that engine detonation might be the cause, the PKBWL investigated this theory against the physical evidence and operational data.
Findings
- The investigation determined that the primary cause was the failure of the piston rings in cylinder number 1.
- This failure allowed oil to enter the combustion chamber, leading to oil combustion and increased frictional resistance, which ultimately seized the engine.
- Physical evidence showed that fragments from the damaged piston rings had become embedded in piston number 1, causing mechanical gouges and material loss.
- While the manufacturer suggested detonation, the PKBWL found no evidence of factors that would cause detonation to affect only a single cylinder.
- Observations during a subsequent test flight with new engines noted higher oil and coolant temperatures on the right engine, suggesting a potential underlying factor contributing to increased operating temperatures.