Incident Overview
On 7 May 2013, an AN-2 aircraft was conducting a repositioning flight from Radom-Piastów (EPRP) to Koszalin-Zegrze Pomorskie (EPKZ). During the third minute of flight, approximately 10 kilometers after passing the KRN (Karnice) radio navigation aid, the engine began to operate irregularly. The pilot-in-command decided to perform a precautionary landing at the nearest airstrip, Sochaczew, which was completed at 10:45.
Inspection and Findings
After landing, a cursory inspection revealed a failure of one of the engine cylinders. The aircraft was anchored, secured, and left at the airstrip. Subsequently, the engine was replaced, and the aircraft returned to service under its Aerial Works Certificate (AWC). The failed engine was examined: cylinder #9 was removed and damage to the piston was identified. However, the cause of the piston damage could not be determined.
Subsequent Operations
From the time of the incident until the user's report in February 2016, AN-2 aircraft operated approximately 1,000 flight hours without any further engine issues.
Probable Cause
According to the investigation, the probable cause of the incident was damage to the piston of cylinder #9 from an undetermined cause, which resulted in uneven engine operation and necessitated a precautionary landing.
Preventive Actions
The investigating entity conducted a refresher training on the principles of engine operation for AN-2 aircraft.
Safety Recommendations
No safety recommendations were issued by the commission.