Accident Overview
An aircraft conducting a survey flight as part of a fire fighting program experienced an engine failure in flight. The crew initiated an emergency landing, but the aircraft stalled and impacted the Varnavka River. The two pilots and one passenger were injured, and the aircraft sank, sustaining damage beyond repair.
Engine Failure and Forced Landing
The engine failed during the survey operation, prompting the crew to attempt an emergency landing on the water surface. During the approach, the aircraft lost lift and stalled, resulting in a crash into the river. The exact circumstances leading to the stall are part of the official investigation.
Official Probable Cause
The investigation determined that the forced landing on water was due to unstable engine operation after a loss of power. The power loss was caused by a re-enrichment of the fuel-air mixture, which resulted from the jamming of the needle valve in the left float chamber of the carburetor. The most likely cause of the valve jamming was clogging by foreign particles. This contamination was attributed to non-compliance with section 2.02.01.20 of the AN-2 maintenance rules during 100-hour maintenance works, compounded by the absence of mandatory compliance requirements from the relevant regulatory technical organization (RTO).
Conclusion
No further analysis or commentary is provided. The facts are as stated in the official accident investigation report.