Avions de Transport Regional (ATR) ATR72-500 frame-24 crack fatigue analysis

Typical passenger aircraft is usually susceptible to heavy landing, fatigue due to expansion and decompression of the cabin, and receiving lots of other external and internal load which eventually causing certain load-bearing structure to be defective, cracked or delamination especially for the composite structures. The idea of this study was initiated from several ATR 72-500 frame 24 cracks that were found during hangar inspection after reaching approximately 24,000 flight cycles. Thus, with regards to this statement, this paper aims to investigate the root cause of the crack and predict the crack occurrences on the frame 24 of the ATR 72-500. By understanding the load exerted and other accounted factors contributing to the crack and its growth, one will be able to find the root cause, provide clearer insights of the process and propose better repair scheme or certain required modification in order to enhance the lifespan of the respective structure. Various methods are being discussed, however the author intent to focus on using finite element method using computer aided engineering in order to simulate the expected results. Thus, by confirming it will be having crack propagation when reaching the required cycle will help operators in preparing suitable maintenance activities to rectify the problem before it occurs.