Design requirements usually include unavoidable stress raisers e.g. holes, fillets and keyways. In the design phase these stess raisers are accounted for by stress concentration factor (SCF), fatigue life of a component or a part is calculated assuming that the material does not have any flaw or initial cracks.The recent development of fracture mechanics open new possibilities to investigate the fracture behaviour of vehicles component and predicting crack propagation. This paper briefly describes crack propagation models and evaluation of structural behaviour under loads where cracks present. Using this approach, repair and inspection interval can be defined.