FAR 21.620 — TSO Quality System Changes
FAR 21.620 requires TSO authorization holders to notify the FAA in writing of any quality system change affecting inspection, conformity, or airworthiness.
FAR 21.620 governs what happens after a manufacturer receives a Technical Standard Order (TSO) authorization — the FAA approval that lets them produce a specific aviation article (like a seatbelt, altimeter, or emergency locator transmitter) to a defined performance standard.
Once that authorization is issued, the manufacturer's quality system isn't frozen in place — it can evolve. But the FAA keeps oversight. Specifically:
- Every change to the quality system is subject to FAA review.
- The TSO authorization holder must immediately notify the FAA in writing of any change that may affect:
- Inspection procedures,
- Conformity of the article to its approved design, or
- Airworthiness of the article.
Why it matters operationally: pilots rely on TSO'd parts being built consistently to a known standard. If a manufacturer quietly alters its inspection or production process, the part you're trusting in flight may no longer match what was certified. This rule keeps the FAA in the loop so safety-critical articles remain trustworthy throughout production.