Products of the metal founding industry are manufactured in a single step from liquid metal without intermediate operation of mechanical working. The advantage of this process is the shaping of all types of pieces either tall, thick or with a complex geometry. However, they may contain several casting defects such as shrinkage defects due to the dendritic growth during solidification. Defects can have an influence on the fatigue limit of the material because of local stress concentration. In the naval industry, before launching, big casting products like marine propellers pass a conformity check through penetrant testing. It is a non-destructive method that allows to reveal surface defects in order to determine critical defects through acceptance criteria based on norms and reference documents. The objective of the study is to understand the acceptation criteria of defects in order to avoid rejects and numerous repairs on CuAl casting propellers. The step of the work are firstly to understand the fatigue behavior of the alloy in the presence of natural defects, then to analyze the reduction of the fatigue limit depending on the size of defects through a Kitagawa-Takahashi diagram. All of the fracture surfaces are analyzed to determine the origin of crack initiation. The final aim is to establish the link between fatigue and penetrant testing, as the results will be described with a Kitagawa-Takahashi / NDT diagram which shows the fatigue limit depending on the size of the penetrant testing indication.