FAR 23.2240 — Structural Durability
FAR 23.2240 requires inspections and design features to prevent structural failure, ensure safe flight after decompression, and limit uncontained engine damage.
FAR 23.2240 sets the structural durability standards for Part 23 (small) airplanes. It requires the manufacturer (applicant) to develop inspections or procedures that catch strength degradation before it leads to a structural failure that could cause serious injury or unsafe operation. These inspections must be published in the Airworthiness Limitations Section of the Instructions for Continued Airworthiness required by § 23.1529 — which is why they're mandatory, not optional, for operators.
Key requirements:
- Level 4 airplanes: procedures must detect structural damage before it could cause failure.
- Pressurized airplanes: must remain capable of continued safe flight and landing after a sudden cabin pressure loss, including from door or window failures.
- Airplanes operating above 41,000 ft: inspections must catch damage to the pressurized cabin before it could cause rapid decompression resulting in serious or fatal injuries.
- The airplane must be designed to minimize hazards from high-energy fragments released by an uncontained engine or rotating machinery failure.
Operationally, this is why pilots see required structural inspections in the AFM/maintenance manual that cannot be deferred.