Off-Nominal Performance and Reliability of Novel Aircraft Concepts During Early Design

Abstract

To achieve improvements in aircraft efficiency and reduced environmental footprint, aircraft must incorporate novel concepts, architectures, and technologies, such as distributed electric propulsion. These new concepts, architectures, and technologies pose an uncertainty related to risk associated with off-nominal operation due to limitations of traditional safety analysis applied to new technologies. Surveyed literature does not completely address the limitations caused by insufficient knowledge and experience with transformative technologies. The present work proposes an integrated safety assessment framework developed previously by the authors to evaluate off-nominal performance and reliability using information that is typically available in conceptual or preliminary design phases. A case study on the electric power architecture of a test distributed electric propulsion aircraft inspired by the NASA Maxwell X-57 Mod-IV is provided. A maximum potential flight-path angle metric and trimmability considerations using a six-degree-of-freedom model help determine hazard severity of power degradation scenarios. Bayesian failure rate posteriors are constructed for the different components in the traction power system, which are used in a Bayesian decision framework to make a compliance assessment.