Description: probability for an item to be in a state to perform as required at a given instant; Name: immediate Availability
Description: Probability that an item is in a state to perform as required at a given instant, under given conditions, assuming that the necessary external resources are provided ; Name: Instantaneous availability
Description: Rotor resonant frequency calculated assuming that the rotor is supported only at its bearings and that the bearings are of infinite stiffness ; Name: Dry critical speed