Economic Impact Assessment of Structural Health Monitoring Systems on the Lifecycle of a Helicopter Blade

Structural Health Monitoring Systems (SHMS) are widely investigated in the literature, however, their application in the aerospace industry is still limited. One of the reasons lies in the lack of methods evaluating their economic impact on the lifecycle of the structures. In this work, the economic impact of a Fibre Bragg Grating (FBG)-based SHMS is assessed on a composite helicopter tail rotor blade, considering two perspectives: Beginning Of Life (BOL), and Middle Of Life (MOL). Two scenarios are compared according to the Life Cycle Costing methodology: the current one, and the one including the SHMS. In the BOL, the FBG's replace the thermocouples, adopted for the development of the curing cycle; while during the blade certification tests, the FBG's replace the strain gauges. In the MOL the SHMS performs automatic scheduled inspections of the tail rotor blade. The lifecycle of the helicopter is implemented in the Probabilistic Damage Tolerance Analysis to compare two scenarios having the same blade Probability Of Failure. The detection performance and false alarms of the SHMS are considered. Results show that an economic benefit may be achieved using the SHMS in the development of a new blade, potentially reducing the number of blade tested and the number of autoclave curing cycles. Moreover, the scheduled detailed inspection interval can be extended if automatic SHMS inspections are performed in addition to it, maintaining the same Probability Of Failure. However, due to the frequent impacts with foreign objects, the repair complexity of a sensorized structure, and its higher cost compared to a standard blade, the economic impact of the SHMS is evaluated as negative on the lifecycle of the blade.