Failure analysis of an aircraft nose landing gear piston rod end

• A failed piston rod end used in an aircraft landing gear has been examined for the cause of failure.
• The fracture surface presents typical features of fatigue failures.
• Fatigue fracture was initiated at the surface close to the mechanically damaged region.
• Mechanically damaged region act as stress raisers and in the present case can be additive factor.

A failure investigation has been conducted on a piston rod end used in a hydraulic actuating cylinder of an aircraft landing gear. The failed piston rod end was found to be broken. An evaluation of the failed piston rod end was undertaken to assess its integrity that included a visual examination, photo documentation, chemical analysis, hardness measurement, tensile testing, and metallographic examination. The failure zones were examined with the help of a scanning electron microscope (SEM) equipped with EDX facility. A stress analysis is also carried out by the finite element technique for the determination of highly stressed regions on the piston rod end. The results indicated that the piston rod end failed by fatigue with cracks initiated at the surface close to the mechanically damaged region due to high stress concentrations.