Manufacturing‑Induced Surface Damage as a Driver for Failure in Aircraft Landing Gear

An investigation was performed to understand the origin of surface damage and cracking observed in aircraft landing gear components manufactured from high‑strength steel. The study combined examination of a fractured in‑service component with comparative analyses of similar parts removed during inspection activities. The objective was to determine how internal surface features influenced crack initiation.

Visual, non‑destructive, and laboratory techniques—including optical and electron microscopy, chemical analysis, and hardness testing—were used to characterize the damage. Smooth, crater‑like features were consistently found on internal surfaces at geometric transitions. These features exhibited evidence of localized thermal damage and microcracking. Chemical analysis identified residues associated with protective surface processing, and localized hardness reductions were measured near the damaged regions, while bulk material properties met specification requirements.

Analysis showed that cracks initiated at the internal surface damage and propagated over time before final overload failure during service. The results demonstrate how manufacturing‑induced surface damage can act as a stress concentrator, promoting crack initiation and emphasizing the importance of process control and internal surface inspection for critical structural components.