The Most Recent Rules on Fatigue and Damage Tolerance - Application and Challenges at Airbus Helicopters

This paper shows the history and background of the motivation for the recently modified rules concerning the evaluation of fatigue and damage tolerance of metallic and composite structures. The most significant modifications which were made compared to the previous ones are discussed, specifically the split into two paragraphs for metallic and composite structure and the change towards performance based regulations. Examples to demonstrate the application on Airbus Helicopters products are the H145 Fenestron™ hub and blade and the H160 main rotor hub plate. For the metallic parts of the Fenestron™ hub a substantiation according to the flaw tolerant fatigue evaluation requirements of the FAR 29.571 was chosen. The thermoset carbon composite blade of the H145 Fenestron™ as the second example illustrates the application of the newly introduced composite requirements. Finally the thermoplastic carbon composite main rotor hub plate for the H160 is presented as a new technology in the first case of full applicability of the new rules to complete new helicopter model.