A method for performing condition-based maintenance of an engine is presented. The method includes obtaining one or more parameters corresponding to the engine. Also, the method includes determining a temperature profile corresponding to a portion of a fluid flow component based on a first parameter and one or more thermal models. The method further includes estimating a solid deposit in the portion of the fluid flow component corresponding to each cycle of the engine based on the temperature profile and deposition kinetics parameters. Further, the method includes predicting a total solid deposit in the portion of the fluid flow component based on the estimated solid deposit corresponding to each cycle of the engine. Moreover, the method includes performing the condition-based maintenance of the engine based on a value of the predicted total solid deposit.