Russia

The failure of the right engine is most likely due to an interruption in the fuel supply due to the presence of dirt in the fuel filter. The left engine lost power presumably due to wear on the cylinders and pistons that had exceeded their life limit. A lack of an effective check of the fuel filters and the life of the various components of the left engines remains contributing factors.

The accident was the consequence of erroneous actions on part of the crew while climbing in instrument meteorological conditions at unreliable readings of instrument speed caused by icing (blockage with ice) of all three Pitot tubes. This caused the aircraft to become uncontrollable, enter a dive and eventually collide with the ground. The accident was then considered as a loss of control in flight (LOC-I). The investigation revealed systemic weaknesses in the identification of hazards and risk control, the inoperability of the airline's flight safety management system and the lack of control over the level of training of crew members by aviation authorities at all levels, which led to the issuance of certificates of aviation personnel and the admission to the flights of the crew, which did not fully meet the qualification requirements. The following contributing factors were reported:
- Hurry of the crew in preparation for the flight due to the late arrival of the aircraft from the previous flight and attempts to "catch up" with the time,
- Skipping by the crew of the operation to switch on the Pitot tube heating before takeoff and failing to comply with the section of the check list "BEFORE TAKE-OFF", which provides for the control of this action,
- Design features of the An-148 aircraft in terms of the restrictions on the duration of Pitot tube heating operation on the ground, which led to the need to carry out operations to control the inclusion of Pitot tube heating and compliance with the principle of "dark cockpit" in a separate section of the "BEFORE THE FLIGHT" check list, which is performed immediately before the start of the takeoff run, which creates additional risks of missing these operations. These actions are provided in the section "ON THE RUNWAY START",
- Systematic failure of the airline's crews to comply with the "dark cockpit" principle and the requirements of the radar, which contributed to "getting used" to the takeoff with the presence of emergency and warning messages on the Integrated system and alarm indicator (KISS) and did not allow to identify the fact that the Pitot tube heating was not included. In the accident flight before takeoff, six warning messages were displayed on the KISS, including three messages about the absence of Pitot tube heating,
- Design features of the An-148 aircraft, connected with the impossibility to disable the display of a number of warning messages on the KISS even when performing the whole range of works provided for by the MMEL while ensuring the flight with delayed defects,
- Low safety culture in the airline, which was manifested in: systematic failure to record in the flight log the failures detected during the flight, as well as in the performance of flights with the failures not eliminated and/or not included in the list of delayed failures, accompanied by the corresponding messages on the KISS,
- Failure to take necessary measures in case of detection of previous facts of untimely activation of Pitot tube heating by crews based on the results of express analysis of flight information,
- Unreadiness of the crew to take actions in case of triggering the alarm "Speed of Emergency" due to the lack of appropriate theoretical training in the airline and the impossibility to work out this special situation on the flight simulation device and / or during airfield training and, as a consequence, failure to comply with the procedures provided for after triggering of this alarm,
- Absence of federal aviation regulations for certification of flight simulators, the development of which is provided for by the Air Code of the Russian Federation,
- Approval for the existing AN-148 flight simulators of the IFC Training LLC and the CTC of the Saint-Petersburg State University of Civil Aviation without taking into account their actual capabilities to reproduce special flight cases, as well as the provisions of FAR-128,
- Absence of specific values of flight parameters (engine operation mode, pitch and roll angles, etc.) in the aircraft's flight manual, which must be maintained by the crew of the airspeed alarm system, as well as absence of the situation with unreliable instrument speed readings (Unreliable Airspeed Procedure) in the list of special flight cases,
- Increased psycho-emotional tension of crew members at the final stage of the flight due to inability to understand the causes of speed fluctuations and, as a consequence, the captain falling under the influence of the "tunnel effect" with the formation of the dominating factor of speed control according to the "own" (left) airspeed indicator without a comprehensive assessment of flight parameters,
- Insufficient training of pilots in the field of human factor, methods of threat and error control and management of crew resources,
- Individual psychological peculiarities of pilots (for the captain - reduction of intellectual and behavioral flexibility, fixation on their own position with the inability (impossibility) to "hear" prompts from the second pilot; for the second pilot - violation of the organization and sequence of actions), which in a stressful situation in the absence of proper level of management of the crew resources came to the fore; loss of the captain's psychological performance (psychological stupor, psychological incapacitation), which resulted in complete loss of spatial orientation and did not allow reacting to correct prompts and actions of the co-pilot, including when triggering the PULL UP warning of the EGPWS system,
- Absence of psychological incapacitation criteria in the airline's AFM, which prevented the second pilot from taking more drastic measures,
- High annual leave arrears for special conditions, which could lead to fatigue and negatively affect the performance of the captain,
- Operation of the aircraft control system in the longitudinal channel in the reconfiguration mode with unreliable signals of instrument speed, not described in the operational documentation, related to a double increase in the transfer coefficient from the hand wheel to the steering wheel in the flight configuration and constant deviation of the steering wheel for diving (without deviation of the steering wheel) for about 60 seconds, which reduced the time required for the crew to recognize the situation.

Loss of control during initial climb due to the combination of an excessive weight (the total weight of the aircraft was 42 kilos above MTOW) and a CofG that was too far aft, well above the permissible limit (32%). Poor flight preparation.

The direct cause of the L410UVP-E20 RA-67047 A/C accident was the uncommanded inflight RH engine propeller blades setting to the angle of minus 1.8° which is significantly below the
minimum inflight pitch angle (13.5°) with TCLs set to forward thrust. It caused the significant rolling and turning moments, the A/C loss of speed and controllability, and the subsequent with the ground collision. The propeller blades' setting to the negative angles was caused by the failures of two systems: the BETA Feedback system and the Pitch Lock system. As the Propeller Pitch Lock system components that are to be tested during the PITCH LOCK TEST most probably did not contribute to the system malfunction, then it is unlikely that the crews' deviation of the PITCH LOCK TEST procedure could have make any difference in the detection of the said system malfunction before the flight. The said situation had been classified as extremely improbable during the aircraft type certification, so, there was no required crew actions in AFM for such situations, and the respective crew training was not required.

The crash of An-2 RA-02305 aircraft occurred during the forced landing. The necessity of the forced landing was caused by the engine stopping in flight due to the destruction of the cylinder head No.1 of the ASH62-IR engine No.K16509153. The destruction of cylinder head No. 1 is of fatigue nature and occurred due to exhaustion of fatigue life of the cylinder head material and reaching its limit state. Most likely, during the last repair of the engine the crack in the cylinder head was present, but was not through and was not revealed during the inspection. The most likely contributing factor to stopping the engine in flight was the impoverishment of the fuel-air mixture due to icing of the BAC filter mesh and the presence of a rubber plug on the filter flange of the corrector.

The most likely cause of the crash of the An-2 RA-35171 was the failure of the PIC to pilot the An-2 aircraft at high flight speeds (an increase in the time required for the aircraft to leave the bank due to the decrease in the angles of the aileron deflection due to the pulling of the cable line due to a significant increase in forces in the transverse of the control channel at speeds of 270-300 km/h), which did not allow the aircraft to arrest the descent when maneuvering with large angles of bank at an extremely low flight altitude.
The contributing factors were:
- Piloting the aircraft at modes beyond the limits set by the AFM of the An-2 aircraft;
- Maneuvering at an altitude less than that established for performing a demonstration flight over the aerodrome.

Loss of engine power due to the failure of the cylinder n°5 caused by a faulty manufacturing.

It was determined that during the approach, the instructor led the aircraft descending below MDA when he simulated an engine failure and positioned both power levers to idle. As a result of the failure of the propeller feathering system, the right engine stopped. After 14 seconds, the instructor mistakenly shut down the left engine that was running properly, causing the aircraft to lose speed, to stall and to crash.

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.