Abstract For advanced airplane, the Safety of Flight tends to be dependent on complex flight control system. The result is a greatly increased emphasis on flight control system failure effects. FAR25 airworthiness standards are based on, and incorporate, the techniques of the fail-safe design concept. Critical FAR25 airworthiness clauses and Special Conditions about flight control system failures are analyzed. Airworthiness requirements and methods of compliance are studied. Key works in flight control system development are summarized. System safety assessments and failure state verification test are conducted for showing the compliance with airworthiness requirements.