Aircraft Systems Qualification Test Definition by Structural Analysis Techniques 2022-28-0081

Aircraft systems have a stringent requirement governed by the certifying authorities demanding that the system and components are qualified for all the applicable requirements. Conducting qualification tests on all the components in a system for all operational requirements, environmental loads, and the loads for uncertainties such as limit and ultimate cases would consume a significant time in the product design cycle. With improved computational power and with validated higher fidelity models, structural analysis is proving to be a way forward in reducing the product design cycle time.

This paper discusses about the structural analysis driven qualification test definition aligning with modes of compliances defined by CS25 / FAR 25 with an objective to minimize and simplify the tests carried out as a step towards certification by analysis. Various aspects such as test simplification, test rationalization, test article selection and test waivers are discussed as part of this paper with the aid of case studies. For instance, fatigue and endurance requirement could be complex in nature with varying load profiles depending on the operational environment such as temperature and flight condition etc. Considerable time is required for setting up test rigs for different profiles. Simplifying test profile by reducing number of cycles, reducing fluctuations, and revolutions save time. Equivalent damage method is proposed for test rationalization; design of loads spectrum block along with truncation of insignificant loads is proposed for test simplification. Similarly test article selection out of various identical LRUs in an aircraft system can be made based on structural analysis considering the severity of the loads applied, static and dynamic similarity as required based on the test requirements.