The greats machines need to have great attention with the components of Tail, gear boxs, couplings and tail rotor, shafts, fatighe of tail boom structure normaly are noted when the machine start up of ground for hover the structure give signals of deformations and torsion with waves noteds on boom near to root and body, these items are the main cause of crashs, also the vibrations of tail are minus noteds because the big ships not transmit it as a litle helicopteres and are not noteds per pilots on the peddals of command, the hight frequecy vibreations destroying the balls of bearings and crash the gears making lost of action of tail rotor, is need to make analisys of vibrations with more frequency per mechanics it is very necessary for safety.