Aviation parts glossary
Plain-English definitions of the terms you'll see across our listings and paperwork.
Updated Sep 18, 2026 MST
- 8130-3 (FAA Form 8130-3)
- The FAA Authorized Release Certificate documenting that a part conforms to approved data and is in a condition for safe operation.
- Aircraft on Ground (AOG)
- An aircraft grounded by a missing or failed part — the highest-priority sourcing situation.
- Airframe & Powerplant (A&P)
- An FAA-certificated mechanic authorized to perform and approve aircraft maintenance.
- Airworthiness Directive (AD)
- A legally mandatory FAA instruction to correct an unsafe condition on a type of aircraft or part.
- Certificate of Conformance (CofC)
- A manufacturer statement that an item was produced to specification.
- EASA Form 1
- The European aviation safety authority's equivalent of the FAA 8130-3 release certificate.
- Illustrated Parts Catalog (IPC)
- The manufacturer's diagram-based catalog used to confirm the correct part for a specific aircraft.
- Inspection Authorization (IA)
- An A&P authorized to perform annual inspections and approve major repairs.
- NATO Stock Number (NSN)
- A 13-digit code (FSC + NIIN) identifying a standardized supply item.
- Overhauled (OH)
- Disassembled, cleaned, inspected, repaired as needed, and reassembled to service limits — with documentation.
- Parts Manufacturer Approval (PMA)
- FAA approval to produce a replacement or modification part.
- Repaired (RP)
- Restored to a serviceable condition by correcting a specific defect, with documentation.
- Service Bulletin (SB)
- A manufacturer notice recommending (not mandating) an inspection or modification.
- Serviceable (SV)
- Inspected and found fit for installation, typically supplied with a serviceable tag.
- Supplemental Type Certificate (STC)
- FAA approval to modify an aircraft from its original type design.
- Suspected Unapproved Part (SUP)
- A part whose conformity to approved data cannot be established — quarantined, never sold.
- Technical Standard Order (TSO)
- A minimum performance standard for specified materials, parts, and appliances.
- Time Between Overhaul (TBO)
- The manufacturer-recommended operating hours between overhauls of a component.