8411.91.90 - Other

This HTS category, 8411.91.90, covers "Other" parts of turbojets or turbopropellers that are not cast-iron parts advanced beyond cleaning and machined only for the removal of fins, gates, sprues, and risers, or to permit location in finishing machinery (as specified under 8411.91.10). Therefore, this heading encompasses a broad range of components for turbojet and turbopropeller engines that do not fit the specific exclusion of partially processed cast-iron parts. This can include machined components, fabricated parts, and any other specialized components utilized in the construction and operation of these types of jet engines.

To understand the scope of 8411.91.90, it's crucial to differentiate it from its sibling. While 8411.91.10 is narrowly defined for specific preliminary processing of cast-iron parts, 8411.91.90 serves as a residual category for all other qualifying parts of turbojets and turbopropellers. This means that any part of these engines, made from various materials and undergoing more advanced manufacturing processes, would likely fall under this classification, provided it is not specifically enumerated elsewhere.

This category further subdivides to distinguish between parts intended for different applications. The subcategories delineate between parts for non-aircraft turbines (8411.91.90.40) and those specifically for aircraft turbines. This distinction is critical for customs purposes, as the intended use, regulatory requirements, and market factors often differ significantly between aviation and non-aviation gas turbine components.