Feasibility of Developing and Implementing a Fatigue Monitoring System for Rotorcraft

Department of Transportation in the interest of information exchange. The United States Government assumes no liability for the contents or use thereof. The United States Government does not endorse products or manufacturers. Trade or manufacturer's names appear herein solely because they are considered essential to the objective of this report. This document does not constitute FAA certification policy. Consult your local FAA aircraft certification office as to its use. The purpose of this study was to investigate the feasibility of a unified Health Usage Monitoring System and damage tolerance approach for the continued airworthiness of rotorcraft. An essential question of feasibility is whether components can be instrumented to monitor precrack fatigue damage. In this feasibility study, a simple specimen was instrumented with sensors for active (pitch-catch) ultrasonic measurements. The specimen was tested in a fatigue test machine. The data from the microsensor system was interpreted and used in a probabilistic fatigue damage procedure that was developed. This procedure provided statistical data on the appearance of a macrocrack that was compared with measurements.