Non-destructive testing was applied to an aircraft tow hook made of forged AISI 4130 alloy steels to evaluate its structural integrity under service conditions. Five inspection methods including magnetic particle, liquid penetrant, eddy current, ultrasonic, and radiographic testing were applied to the same component and correlated with finite element stress analysis. Eddy current, ultrasonic, and radiographic methods proved ineffective due to material ferromagnetism, complex geometry, and field equipment limitations, while liquid penetrant testing detected surface indications but suffered from a high level of non-relevant responses. In contrast, magnetic particle testing reliably identified a linear surface crack approximately 13 mm long at the inner curvature near the attachment region. Finite element analysis indicated a yield utilization of approximately 43%, corresponding to a safety factor of about 2.3 under nominal towing loads, and fracture-mechanics evaluation yielded a critical crack length of 19.6 mm, indicating that the observed defect had reached about 66% of the critical value. The strong agreement between experimental crack detection and numerical stress predictions demonstrates the value of integrating targeted NDT with finite element analysis and confirms magnetic particle testing as the most reliable inspection method for forged AISI 4130 aircraft tow hooks under realistic field conditions.
