The theoretical underpinnings of spare parts optimization are rooted in Sherbrooke's METRIC model~\cite{ref3}, which established the inaugural multi-echelon control framework for recoverable items and served as the prototype for both military and commercial MRO systems. Muckstadt~\cite{ref4} later expanded this to multi-indenture structures, which are like the hierarchical structure of aircraft assemblies. Ghobbar and Friend~\cite{ref5} focused on the demand side by listing the uneven and sporadic patterns that are typical of aviation spares and comparing the accuracy of traditional forecasting methods. These contributions collectively established a substantial optimization literature, predominantly centered on cost and availability rather than environmental impact.

Spare parts optimization theory traces back to Sherbrooke's METRIC model, which created the first multi-echelon control system for recoverable components and became the foundation for military and commercial MRO operations. Muckstadt built upon this work by incorporating multi-indenture structures that mirror the hierarchical organization of aircraft assemblies. Meanwhile, Ghobbar and Friend examined demand patterns, documenting the irregular and intermittent characteristics common to aviation spare parts while evaluating how well traditional forecasting approaches performed. These foundational works created an extensive body of optimization research that has primarily emphasized cost considerations and availability metrics rather than environmental concerns.