CCAR25.671(d) specifies that the airplane must be designed so that it is controllable if all engines fail. Aiming at the above requirement specified in Transport Category Airplanes Airworthiness Standards issued by Civil Aviation Administration of China, compliance methods of Flight tests(MOC6) and Engineering Simulator Tests (MOC8) are proposed for the Flight Control System of a certain type civil aircraft. First, FAA Aviation Rulemaking Advisory Committee (ARAC) explanation and suggested evaluation approaches for CCAR25. 671(d) are expatiated; Second, effects of all engines fail on a certain type civil aircraft and its flight control system are analyzed; Third, the compliance validation approaches, fault simulated methods,test procedures and the acceptable criterions for MOC6 and MOC8 methods are detail introduced separately. Methods presented herein provide a valid approach for justifying that the design of the Flight Control System of civil aircraft is compliant with CCAR25.671(d).