Strength Evaluation of a Sliding Helicopter Fairing/Door Subject To Load and Impact Velocity Interaction

This paper describes a multidisciplinary strength study of a helicopter sliding fairing/door submitted to dynamic loads coming from impact velocity. Those loads result both from opening/closing procedure before or during flight and from handling manoeuvres. They are typically not considered in helicopter regulations and might be more critical than the aerodynamic load cases required for strength substantiation and helicopter certification. These loads caused indeed incidents in service and were thus deeply analyzed. This paper intends to describe: • The technical approach used to determine those impact loads depending on the surrounding stiffness, friction/stroke on sliding mechanism and impact velocity. • The dedicated means to perform static, dynamic and fatigue substantiation of sliding parts considering these loads (based on finite element model and laboratory test analysis). • The importance of fractography analysis to understand failure modes of parts submitted to aerodynamic and impact loads. In conclusion, general concepts of design recommendations following this study are presented.