Impact Analysis of Uncontained Engine Rotor Debris on Rotorcraft Structure

Engine failure hazard effect analysis has to be demonstrated by all rotorcraft manufacturers. To meet the safety objective, the hazardous effects of uncontained rotor burst debris on the aircraft structure and occupants are evaluated. A qualitative assessment for each critical system/component is studied for uncontained rotor burst fragments including translational and spread risk angles using the geometrical method as per AC 20-128A. In this paper, the critical power turbine uncontained disc fragment is considered for hazard assessment as per FAR/CS 29.903(d). The LS-Dyna nonlinear transient code is used as a part of risk analysis to show airworthiness compliance. A simulation model using LS-Dyna is developed for structural elements like the engine deck, instrument panel, and floorboard with detailed FE idealization and contact definitions to accurately predict debris penetration through structural elements. The energy absorption in each structural member is calculated.