FAR 21.301 — PMA Applicability

FAR 21.301 is the opening section of Subpart K of Part 21, which deals with Parts Manufacturer Approvals (PMAs). A PMA is the FAA approval that allows a company to manufacture and sell replacement and modification parts for installation on type-certificated aircraft.

This section simply tells you what the rest of the subpart will cover. Specifically, Subpart K prescribes:

• Procedural requirements for issuing PMAs (how a manufacturer applies for and obtains approval), and
• Rules governing holders of PMAs (the ongoing responsibilities once a company has been granted a PMA).

Why it matters operationally: As a pilot, you generally won't apply for a PMA, but you should understand that any non-original-equipment part installed on your aircraft must be FAA-approved, often via a PMA. When reviewing maintenance logbooks or 8130-3 tags, you'll see PMA references — knowing where these approvals come from helps you verify your aircraft is airworthy and legal to fly.