Bilateral Aviation Safety Agreements (BASAs) between the US and partner countries—such as the EU, Canada, Brazil, and Japan—allow airworthiness approvals issued by one authority to be accepted by the other, streamlining customs entry and reducing duplicative testing. Without a BASA, imported parts may require independent FAA validation, adding time and cost to the supply chain.

Complete civilian aircraft above a certain weight threshold typically enter under a duty-free or low-duty HTS provision, but the specific treatment depends on the aircraft's type certificate, country of manufacture, and applicable trade agreements. Importers of complete airframes should file a formal entry and confirm classification at the 10-digit HTS level, as engines, avionics, and structural parts each carry separate tariff treatment.