Aviation parts glossary.

13-digit identifier the U.S. and NATO supply systems use to catalog every standardized item.

Last nine digits of an NSN — the unique item number worldwide.

First four digits of an NSN — the federal supply category.

Five-character code identifying a supplier or contractor.

Airworthiness approval tag for new and overhauled parts from FAA-approved sources.

European airworthiness approval — the EASA equivalent of FAA 8130-3.

Supplier statement that the part conforms to PO requirements and cited specs.

Trace pack standard for used-serviceable, surplus, or parts-out aviation material.

Continuous supplier history back to the last installed-on operator or OEM.

Aircraft grounded for maintenance — every minute is revenue lost.

Repairable aviation component that moves through the overhaul cycle.

Single-use aviation part replaced rather than repaired.

Non-installable aviation materials — lubricants, sealants, paints, packaging.

Restored to a known service condition by an FAA / EASA-approved repair station.

Used-serviceable with documented chain-of-custody and condition statement.

Pulled from service with last-operator pedigree but not yet inspected or repaired.

Part-number cross-reference that an operator may approve in place of the original.

Approved interchange relationship between part numbers — operator-controlled.

FAA-approved alternate to OEM under a PMA letter for a specified application.

Original Equipment Manufacturer — the airframe, engine, or component maker.