Currently, the analysis of crack propagation in typical metal components of helicopters in service, which are used for engineering purposes, mainly relies on empirical and engineering algorithm assessments. There is a lack of theoretical basis and effective crack propagation analysis methods. In this paper, based on finite element software and combined with the XFEM calculation method, the influence of loading methods for typical metal components, including initial defects (corrosion) and structural reinforcement (sheet metal stamping) factors, on crack propagation is studied. In addition, a crack propagation simulation analysis calculation is carried out for an example of a helicopter long boom structure with an initial crack. The calculation results are consistent with the actual crack propagation results. The methods and conclusions described in the article provide references for predicting the crack propagation path and damage tolerance design of typical metal structural components of helicopters, and have certain value for engineering practices.