methods and apparatus are provided for predicting ice formation on and shedding from blades of an air cycle machine turbine . the method comprises generating operational condition data representative of acm turbine operating conditions using a software model of the acm , determining an amount of ice formation on the blades of the acm turbine , and determining an amount of ice shed from the blades of the acm turbine . the apparatus comprises means for generating operational condition data representative of acm turbine operating conditions using a software model of the acm , means for determining an amount of ice formation on the blades of the acm turbine , and means for determining an amount of ice shed from the blades of the acm turbine . in some embodiments , the means and apparatus may also involve predicting acm wear , based at least in part on the predicted ice formation and shedding .