What happened
On May 7, 2013, an AN-2 aircraft was performing a repositioning flight from Radom-Piastów (EPRP) to Koszalin-Zegrze Pomorskie (EPKZ). Approximately three minutes into the flight, specifically 10 km after passing the KRN (Karnice) radio navigation aid, the engine began operating irregularly. In response to the engine instability, the pilot decided to perform a precautionary landing at the nearest available airfield, Sochaczew. The aircraft landed safely at 10:45.
Following a preliminary inspection on the ground, it was determined that one of the engine cylinders had failed. The aircraft was subsequently secured and left at the airfield.
The investigation
The investigation, conducted by the operator's commission, focused on the engine failure. After the engine was replaced, the aircraft returned to service under an Aerial Works Certificate (AWC). The failed engine was inspected, and upon removing cylinder number 9, investigators discovered damage to the piston. While the physical damage was confirmed, the specific origin of the piston failure could not be determined.
Findings
- The irregular engine operation was caused by the failure of cylinder number 9.
- The investigation identified damage to the piston as the primary factor, though the underlying cause of this damage remains unknown.
- Since the incident, the AN-2 fleet operated by the user has completed approximately 1,000 flight hours without similar engine malfunctions.