Abstract: Notions of probability of structural function failure, probability of function failure for one aircraft and probability of function failure for a fleet are presented. Based on the binomial distribution, a calculating model of structural function failure probability for a durability critical component, one aircraft and a fleet is established. It accounts for structural maintenance procedure after a certain service time. An analytical method capable of determining the repair maintenance time and estimating the service life for aircraft structures is developed based on the function failure probability control. A practical aircraft structural service life estimation, as an example, to demonstrate the application of the methodology is given.