Failure-Informed Standardization of Pulse-Echo Ultrasonic Inspection for Motor Grader Spindle Shafts After Field Fractures

Sanchez Collque R.A.; Huarca Pulcha A.; Mamani-Calcina E. · Journal of Failure Analysis and Prevention (2026) · DOI: 10.1007/s11668-026-02482-x

Resumen

Failures of steering-related spindle shafts in heavy motor graders can lead to unplanned downtime and high repair costs. In field ultrasonic testing (UT), false-negative outcomes may occur when equipment configuration, scan coverage, and interpretation criteria are not standardized, particularly in components with complex internal geometry and limited inspection access. This case history presents a practical and repeatable pulse-echo ultrasonic inspection protocol for motor grader spindle shafts. The protocol specifies equipment configuration, pre- and post-inspection calibration checks, fixed baseline settings with controlled gain adjustment, failure-informed inspection zone, a consistent scanning sequence, and a quadrant-based reporting scheme to reduce operator-dependent variability. The procedure is documented step-by-step and supported by documented field observations, including a fracture event in which a conventional UT inspection reported no relevant indications shortly before component failure. When the standardized protocol was subsequently applied to similar components in service, repeatable A-scan indications consistent with crack-like responses were observed within the failure-associated inspection region, supporting conservative maintenance decisions, including component replacement or short-interval re-inspection. The contribution of this work lies in the failure-informed formalization of a traceable inspection workflow. The presented field evidence supports the practical value of procedural standardization for providing a more consistent and traceable framework for the interpretation of crack-like indications through calibration control, focused scan coverage, and alignment with observed failure mechanisms. The evidence is qualitative and case-based, emphasizing repeatability and failure correlation rather than probabilistic detection metrics, and was obtained without introducing new ultrasonic technology. © ASM International 2026.

Instituciones: Universidad Nacional de San Agustín de Arequipa