8409.10.00.40 - For use in civil aircraft

This HTS category, 8409.10.00.40, specifically encompasses parts and accessories that are designed and intended for use solely or principally with the engines of civil aircraft. This includes components that are essential for the operation, maintenance, or repair of these specialized engines, such as turbine blades, fuel injectors, combustion chambers, and various sealing components, provided their primary application is within the civil aviation sector.

This classification is distinguished from its sibling category, 8409.10.00.80 ("Other"), by its exclusive focus on civil aircraft engine components. The "Other" category would capture parts for engines of headings 8407 or 8408 that are not specifically intended for civil aircraft, potentially including those for military aircraft, industrial machinery, or other non-aviation applications. Therefore, the critical distinguishing factor is the intended end-use in civil aviation.

As this is a leaf node within the HTS, there are no further subcategories. Classification within 8409.10.00.40 is therefore determined by the part's suitability for use with civil aircraft engines, its role within the engine's overall function, and its origin (i.e., not being parts for engines of heading 8407 or 8408 not for aircraft). The guiding principle is the definitive connection to the operation of engines powering civil aircraft.