Abstract: Maintainability is a critical factor that will decide the maintenance quality and life cycle cost of product. Maintainability modeling plays an important role in maintainability design, and it affects maintainability of product significantly. Maintainability modeling method is deeply studied：Maintenance entities including maintenance object, maintenance resources and their status are described by places and colored tokens which are basic elements of colored stochastic time Petri net; the description method of relationship between maintenance entities and maintenance tasks, and logic relationship of maintenance tasks are also given with the basic elements including places, colored tokens and stochastic time transitions; and the colored stochastic time Petri net based maintenance process model is built on the basis of the above mentioned work. According to the model, maintenance time simulation algorithm based on Monte Carlo method is proposed, as well as demand quantity calculating method of maintenance resources. At last, an application case of maintenance process modeling, maintenance time simulation and maintenance resources demand calculation combined with nose landing gear system of a certain type of aircraft is given to illustrate the superiority of the model and method.

Key words: Maintainability evaluation, Maintainability modeling, Maintenance process, Monte Carlo method, Petri net