Krasnodar Krai

The aircraft collided with the wires of an overhead power line, which had no night markings, with subsequent collision with trees and ground.
The following contributing factors were identified:
- Inadequate experience of the pilot in night flying conditions,
- Violation of the AN-2 flight manual, which prescribes instruments night flights,
- Decision to fly at night to a landing site without adequate light equipment,
- Flying at an altitude lower than the prescribed altitude of unlit obstacles, of which the pilot was aware,
- Decision of the pilot to perform the flight in a reduced crew configuration (without a copilot).

The aircraft overrun, destroying and damage by fire were caused by the following factors:
- repeated disregarding of the windshear warnings which when entered a horizontal windshear (changing from the head wind to tail one) at low altitude resulted in landing at distance of 1285 m from the RWY threshold (overrunning the landing zone by 385 m) with the increased IAS and tail wind;
- landing to the runway, when its normative friction coefficient was less than 0.3 that according to the regulations in force, did not allow to land.
The factors contributed the accident:
- the crew violation of the AFM and Operator's OM requirements in regards to the actions required a forecasted or actual wind shear warning;
- use of the automatic flight mode (autopilot, autothrottle) in the flight under the windshear conditions which resulted in the aircraft being unstable (excess thrust) when turning to the manual control;
- lack of prevention measures taken by the Operator when the previous cases of poor crew response to windshear warning were found;
- insufficient crew training in regards to CRM and TEM that did not allow to identify committed mistakes and/or violations in good time;
- the crew members' high psychoemotional state caused by inconsistency between the actual landing conditions and the received training as well as the psychological limit which was determined by the individual psychological constitution of each member;
- insufficient braking both in auto and manual mode during the aircraft rollout caused by the insufficient tyre-to-ground friction aiming to achieve the specified rate of braking. Most probably the insufficient tyre-to-ground friction was caused by the significant amount of water on the RWY surface;
- the aerodrome services' noncompliance of Sochi International Aerodrome Manual requirements related to the RWY after heavy showers inspection which resulted in the crew provision of wrong normative friction coefficients. In obtaining of the increased overrun speed of about ≈75 kt (≈140 km/h) the later setting of engines into reverse mode was contributed (the engines were set into reverse mode 16 s later than the aircraft landed at distance of about ≈200 m from the runway end).

The accident was the consequence of a loss of control that occurred during initial climb by night over the sea after the pilot-in-command suffered a spatial disorientation due to an excessive neuropsychic stress combined with fatigue.

The accident with An-2 RA-17890 aircraft was caused by its nosing-over during the emergency landing at the submerged rice bay. The emergency landing was due to the engine power loss in flight caused by the destruction of the can type combustor of the exhaust collector and burnout of the carburetor intake valve with the following high-temperature gases ingestion in the intake areas of the engine carburetor. The fatigue destruction of the can type combustor of the exhaust collector was caused along the main crack near the intake flex socket, it started from the surface of the damaged inlet port under the tube attachment pin towards the exhaust collector. By the moment of the main crack formation both inlet ports in left can type combustor under the tube attachment pin towards the exhaust collector had intolerable damage and size. During the last overhaul of the engine exhaust system of An-2 RA-17890 aircraft the left can type combustor had intolerable damage in its attaching lug to the exhaust collector which wasn't eliminated. The destruction of the inlet port valve was caused by the fusion of the boundaries of it material grains in conditions of acute temperature exposure induced by the destruction of the left can type combustor wall towards the main crack. Inadequate material (aluminum alloy D-16) of the valve specified by the drawing of aluminum allow AL-9T contributed to the valve destruction.

The accident was caused by its nosing during the emergency landing on water surface. The emergency landing was caused by the engine power loss and flameout in the air due to the destruction of the exhaust collector can type combustor and burn through of the carburetor intake valve followed by high temperature burnt gases ingestion into the engine carburetor intake. The destruction of the exhaust collector can type combustor most probably occurred on the corrosion mechanism energized in conditions of the material heat during the engine operation using motor petrol. Power factor resulted in initial crack formation most probably was caused by residual tenses in the material of manufacture origine caused during can type combustor manufacture. In accordance with the passport the latest can type combustor overhaul was performed on January 27, 2009 in "Shakhtinsky ARZ DOSSAAF" CJSC. The commission didn't find the actual confirmation of the can type combustor overhaul as the marking at the single remained label indicates that the specified section had overhaul at the plant n° 420GA in October 1983.

The cause of the accident without casualties to the plane An-2 RA-81514 was a violation of the established safe obstacle clearance in the performance of aviation-chemical works, which led to a collision with the lightning protection wire transmission line and the ground. A contributing factor was the performance of an incomplete flight crew. According to the An-2 Flight Manual the minimum crew for aerial chemical works is the commander of the aircraft and a copilot.