We constructed an analytical model of the loading of a specimen with a fatigue crack. We also designed instruments to detect a signal proportional to the change in the compliance (stiffness) of the test specimen. An instrument system was also developed to record the kinetics of cracks during long fatigue tests. Examination of the system in preliminary tests showed it to be highly reliable, providing stable readings of the parameters being recorded. A method was devised for experimentally studying the kinetics of fatigue fracture of specimens of alloy EP718ID and a cycle of tests was conducted. It was shown that life of the specimen after the formation of a fatigue crack depends on the level of the cyclic stresses and stress concentration.