7 ноября  Як-18Т RA-44302

     The Interstate Aviation Committee Investigation team has completed the investigation of the accident with Yak-18Т series 36 RA-44302 aircaft owned by Sasovo civil aviation flight school occurred in the Ryazan Region (RF) on November 7, 2012.
     The fatal accident with Yak-18Т RA-44302 aircraft was caused by flight speed loss by the crew and aircraft beyond stall angles and stall entry followed by ground impact performing emergency approach at the departure place. Decision of the pilot-instructor to perform emergency approach most probably was due to power unit instability at the low flight altitude after take-off resulted in substantial rotor speed oscillation.
     Power unit instability most probably was caused by M-14P 2nd series engine, AV 803-1 propeller, R-2 series 04 constant-speed governor and MS-20 oil joint operation out-of-balance. It wasn't possible to determine the cause of out-of-balance including possible influence of pilot spool bushing and R-2 series 04 governor pressure reducer valve seat avaliable damage in a shape of marks, scratches and depression marks and deviations of MS-20 oil from GOST requirements. 
     The following factors most probably contributed to the fatal accident (the factors are presented in logical order, without assessing the priorities):
     • non-compliance with required workscope on authorization of R-2 series 04 constant-speed governor for joint operation with AV-803-1 propeller as a component of power unit at Yak-18T series 36;
     • non-compliance with recommendations of the Investigation team of the major aircraft incident with Yak-18Т series 36 RA-44309 aircraft occured at Ulyanovsk (Baratayevka) airport on September 1, 2009; 
     • lack of recoomendations for the crew actions in case of uneven engine running;
     • lack of decision by the crew on flight interruption after multiple evidences of power unit abnormal operation in previous flights;
     • pilot-instructor insufficient training for actions in the situation without minimum requirements on proficiency and flight practice in the avaliable regulations on pilots-instructors training and flight practice as PIC at the type of aircraft for training.
     Low level of training flights at Pitelino landing place and nonoperation of flight safety control system in Sasovo civil aviation flight school resulted in unability of safe emergency straight ahead landing due to the lack of avaliable landing places performing 230° take-off heading.
     The appropriate safety recommendations based on the investigation results were developed.