FAR 21.53 — Statement of Conformity

FAR 21.53 governs how applicants seeking type certification confirm that what they're presenting to the FAA actually matches the approved type design. It applies during the certification process for aircraft engines, propellers, aircraft, and parts submitted for FAA testing.

The rule has two parts:

• (a) Engines and propellers: Each applicant must provide, in a form and manner acceptable to the FAA, a statement of conformity declaring that each engine or propeller presented for type certification conforms to its type design.
• (b) Aircraft and parts for testing: For each aircraft (or part of one) presented for FAA tests, the applicant must submit a statement of conformity that also confirms compliance with § 21.33(a) — the inspection and test requirements — unless that paragraph authorizes otherwise.

Why it matters operationally: this statement is the manufacturer's formal accountability that the test article is built to spec. Without it, FAA inspectors and test pilots have no documented basis to begin certification flight or ground testing.