Managing spare parts inventories in commercial aviation is particularly difficult because parts are expensive, safety standards are high, and demand patterns are often unpredictable~\cite{ref1}. Traditional inventory policies have usually put cost-cutting and service-level goals first, with environmental sustainability coming in second place~\cite{ref2}. The International Air Transport The world is changing quickly. The International Air Transport Association (IATA) has told airlines that they must have net-zero carbon emissions by 2050. This changes sustainability from a reporting requirement to an operational requirement. Maintenance, Repair, and Overhaul (MRO) operations add a lot to an airline's Scope 3 emissions, mostly by buying new parts and getting rid of old stock. Therefore, a major problem for the industry is how to reduce this footprint without affecting the availability of aircraft. This paper fills in the gaps by suggesting a unified framework that balances three goals at once: being ready for business, being cost-effective, and being environmentally friendly. The specific contributions are: (1) a hybrid XGBoost-LSTM forecasting model that takes into account environmental factors when predicting demand; and (2) a multi-objective inventory optimization formulation that directly punishes carbon footprint alongside cost and stockout risk; and (3)~a circular economy recommendation engine that extends part lifecycles through structured reuse, remanufacture, and recycling pathways.

Commercial aviation faces unique challenges in spare parts inventory management due to expensive components, stringent safety requirements, and irregular demand patterns. Conventional inventory strategies have typically prioritized cost reduction and service levels, while treating environmental sustainability as a secondary concern. The landscape is shifting rapidly. The International Air Transport Association (IATA) has mandated that airlines achieve net-zero carbon emissions by 2050, transforming sustainability from a compliance issue into an operational imperative. Maintenance, Repair, and Overhaul (MRO) activities contribute significantly to an airline's Scope 3 emissions, primarily through new part procurement and obsolete inventory disposal. The industry now faces a critical challenge: minimizing this environmental impact while maintaining aircraft availability. This paper addresses these gaps by proposing an integrated framework that simultaneously optimizes three objectives: operational readiness, cost efficiency, and environmental responsibility. The key contributions include: (1) a hybrid XGBoost-LSTM forecasting model that incorporates environmental considerations into demand prediction; (2) a multi-objective inventory optimization approach that directly penalizes carbon footprint along with cost and stockout risk; and (3) a circular economy recommendation system that maximizes part lifecycles through systematic reuse, remanufacturing, and recycling processes.