Case study: Analysis of the response of an aircraft structure caused by a propeller blade loss

Abstract

One of the most severe failures in an aircraft provided with turboprops is an airscrew blade loss. Design precautions must be taken to minimize the hazards to the airplane in the event of a propeller blade failure. One of the hazards which must be considered include structural damage, and the airplane must be designed for the imbalance loads resulting from the failure. The structure must absorb the dynamic loads while the rest of the aircraft continues flying. If the energy of the phenomenon increases until it behaves uncontrollably, the engine could be detached from the structure. There must be devices which react to decrease the risks of critical failure for the rest of the structure. This article is mainly focused on the response of the structure after the break of a propeller blade until the end of the phenomenon. The detached propeller blade is also studied in terms of the size that is lost and its influence on the system behavior. Moreover the effects of stiffness and strength changes on the engine mounting system are analyzed. The research covers different parameters which can influence the phenomenon, including flight condition, propeller rotational frequency, and angular position where the blade is lost. The engine and the engine mounting system have been modeled in a finite element method (FEM). The simulations are run in an explicit solver and the simulation methodology includes failure of elements and non-linear behavior.