VESTNIK of Samara University. Aerospace and Mechanical EngineeringVESTNIK of Samara University. Aerospace and Mechanical Engineering2542-04532541-7533Samara National Research University512110.18287/2541-7533-2017-16-2-75-80UnknownCriterion assessment of the possibility to prolong the service life limit of the helicopter tail drive shaftMashoshinO. F.<p><span lang="EN-US">Doctor of Science (Engineering), Professor<br />Head of Department</span></p>o.mashoshin@mstuca.aeroSemenikhinR. L.<p><span lang="EN-US">Candidate of Science (Engineering)<br />Product Support Engineer</span></p>airroman1980@gmail.comMoscow State Technical University of Civil AviationJSC “Helivert”2007201716275802007201720072017Copyright © 2017, VESTNIK of Samara University. Aerospace and Mechanical Engineering2017<p>Low life time of home-produced helicopter transmission elements in comparison with foreign analogues is one of the problems of Russian helicopter industry. For example, the service life limit of Mi-2 drive shaft is 4,500 hours, the time between overhauls is 1,500 hours. The time between overhauls for the drive shaft of a similar helicopter Bell 429 is 3200 hours, for the Eurocopter AS350 it is 3000 hours. The service life limit of the drive shafts of Bell 429 and Eurocopter AS350 is not specified. As the financing of operations to prolong the service life limit of high-load elements of aircraft structure is very limited it is necessary to suggest other, less labor-intensive ways of assessing the technical condition of these elements in order to prolong the service life limit. New criteria need to be introduced to solve this problem. New criteria for the assessment of the possibility of prolonging the assigned life of helicopter tail rotor drive shafts are proposed and scientifically justified in this article. The criteria indicate changes in chemical, physical and mechanical properties, as well as strength properties of products after some time of service. Comparing the properties with their maximum values we can make a conclusion about the possibility to prolong the life cycle of helicopter transmission components. An example of the criteria calculation for the Mi-2 helicopter tail drive shaft with an expired Service Life Limit of 4500 hours is given.</p>Вертолётхвостовой валпродление ресурсовтехническое состояниекритериихимические свойствафизико-механические свойствапрочностные свойстваHelicoptertail rotor drive shaftprolonging the service life limitcriteriachemical propertiesphysical and mechanical propertiesstrength properties[1. Semenikhin R.L. Assessment of Mi-2 drive shaft resourceability. Civil Aviation High Technologies. 2010. No. 160. P. 108-115. (In Russ.)][2. GOST 10006-80. Metaltubes. Tensile test method. Moscow: Standartinform Publ., 2010. 12 p. (In Russ.)][3. ГОСТ 4543-71. Structural alloy steel bars. Specifications. Moscow: Izdatelstvo Standartov Publ., 2000. 40 p. (In Russ.)][4. Mashoshin O.F. Diagnostika aviatsionnoy tekhniki [Diagnostics of aeronautical equipment]. Moscow: Moscow State Technical University of Civil Aviation Publ., 2007. 141 p.][5. Semenikhin R.L. Calculated evaluation of Mi-2 drive shaft strength reserve. Civil Aviation High Technologies. 2014. No. 205. P. 81-85. (In Russ.)][6. Borodin N.A. Soprotivlenie materialov [Strength of materials]. Moscow: Drofa Publ., 2001. 288 p.]