In this simple exercise, we want to monitor the degradation of a wind turbine over a period of a few years. We already know the physical model of a turbine and we also know that the efficiency of a wind-turbine can decrease linearly by about 16% every 10 years (How does wind farm performance decline with age? Renewable Energy, Volume 66, June 2014, Elsevier, available at https://www.sciencedirect.com/science/article/pii/S0960148113005727).