16. The computer readable program storage device according to claim 11 , wherein the initial crack size PDF is determined by: p ⁡ ( A | D ) = f A | D ⁡ ( a ) = 1 a ⁡ ( σ ɛ / β ) ⁢ ϕ ⁡ ( ln ⁢ ⁢ a - ( ln ⁢ ⁢ a ′ - α ) / β σ ɛ / β ) where a is an actual size of a flaw, α and β are fitting parameters, σ ε is a standard deviation, a′ is a value of a reported flaw size and Φ(·) is a standard normal probability density function.
11. A non-transitory program storage device readable by a computer, tangibly embodying a program of instructions executed by a fatigue life prediction processor to perform methods steps for probabilistic fatigue life prediction for a part of a turbine, the method comprising the steps of: in the fatigue life prediction processor, receiving a probability of detection model; in a fatigue life prediction processor, receiving an initial crack size probability density function (PDF) for the turbine part based on the received probability of detection model; in the fatigue life prediction processor, receiving probabilistic identification of model parameters; in the fatigue life prediction processor, receiving a model parameter PDF based on the received probabilistic identification of model parameters according to: 
 ƒ(ln C,m )˜MVN(μ (ln C,m) ,Σ (ln C,m) ), where MVN is a multivariate normal distribution, C and m are model parameters from fatigue testing data, μ (ln C,m) is a mean vector and Σ (ln C,m) is a covariance matrix; providing a crack growth model based on the received initial crack size PDF, the model parameter PDF and material/load factors; determining uncertainty propagation using an analytical or simulation-based method based on the crack growth model based on uncertainty of at least one of material properties, geometries, sensitivity of instruments, and loading of the turbine part; providing fatigue life prediction based on the uncertainty propagation and crack growth model; and implementing a maintenance plan for the turbine part based on the fatigue life prediction.