FAR 23.2205 — Systems and Structures Interaction
FAR 23.2205 requires Part 23 applicants to account for systems that modify structural performance, including their influence and potential failures.
FAR 23.2205 is a Part 23 airworthiness rule that applies when an airplane uses systems that affect its structural performance. Examples include load-alleviation systems, fly-by-wire flight controls, or stability augmentation that reduces structural loads. Because these systems can change how the airframe experiences stress, the certification applicant can't just analyze the airframe in isolation.
Under this section, the applicant must:
- Account for the influence of any system that modifies structural performance, alleviates the requirements of Subpart C (Structures), or is used as a means of compliance with structural rules.
- Account for the failure of those same systems when demonstrating compliance.
Why it matters operationally: If a system that normally limits loads or augments stability fails, the airframe still has to handle the resulting flight conditions safely. This rule ensures the airplane is certified to be structurally sound both with the system working and after it fails — protecting pilots from structural surprises following a system malfunction.