FAR 21.16 — Special Conditions
FAR 21.16 explains how the FAA issues special conditions when existing airworthiness rules don't cover novel or unusual design features of aircraft, engines, or propellers.
FAR 21.16 gives the FAA authority to write special conditions when the existing airworthiness rules in this subchapter don't adequately cover an aircraft, aircraft engine, or propeller because of a novel or unusual design feature.
In plain terms: when a manufacturer brings something new to certification — think canard configurations, composite primary structure, fly-by-wire systems, or unconventional engine architectures — the standard Part 23, 25, 27, 29, 33, or 35 rules may not address the safety risks. Rather than letting the design slip through a regulatory gap, the FAA prescribes extra, tailored safety standards for that specific product.
Key points to remember:
- Special conditions are issued under the rulemaking procedures of Part 11.
- They must establish a level of safety equivalent to that already required by existing airworthiness regulations.
- They apply to the specific aircraft, engine, or propeller with the novel feature.
Why it matters operationally: as a pilot, you may fly aircraft (especially newer or experimental-derived type-certificated designs) whose type certificate data sheet references special conditions. Those conditions are part of the certification basis and explain why the aircraft is considered airworthy despite not fitting neatly into the standard rules.