Abstract The aim of this paper was to determine the critical crack length of a structural component of a helicopter, the component was a flanged plate with a hole in the centre with the aim of making the component lighter. This was verified by setting an objective to develop a method to model and study cracks in aerospace components. Advanced fracture tools in ANSYS workbench were used to achieve this. First the tools were applied to a flat plate where the results were compared to theoretical hand calculations. There was a difference between the results that were usually between three and four percent, this was explained by the different assumptions that each method relies on. Justifications were made that the helicopter component could be considered similar to the flat plate and therefore the method was also applied to the helicopter component. A mesh sensitivity analysis was performed on each of the components to prove that the results were independent of the number of elements in the mesh. The data gathered for the helicopter component was analysed using a polyfit function in MATLAB which produced an equation for the data, this was then solved for when the stress intensity factor was 33.4 MPa.m0.5 and resulted in a crack radius of 4.6352 mm. This value fulfilled the aim of this project. The report concludes that there is a level of uncertainty that is associated with this value which would require experimental data to determine, but that there is reason to believe that the value of 4.6352 mm is close to the real value of critical crack radius.