A shock absorber cylinder of aircraft landing gear leg was used as object of investigation. In process of testing the fatigue crack was grew during action of periodic loading which imitates full cycle including take-off landing and running at the ground. This testing was finished by destruction of the piston rod of shock absorber. Different acoustic emission (AE) parameters have been measured during object loading. It was noted great irregular changes of AE parameters in the different stages of loading. Correlation of AE signal and crack growth development was set by fractal analysis, which carried out by electron-scan microscope and X-ray spectrum analyzer. The relief changes and spectral characteristics of material are researched. It was that fatigue destruction was begun from international surface and an intra-grain crack has been initiated destruction of the material. It is shown that cumulative AE may be used for determination of initiation of fatigue crack and principal stages of their development.