Aircrafts and or its components are subject to failure during its normal.operation. These failures may be recti-fied at different repair rates Al, A2, A3....Ak with corresponding repair costs rj, r2, r3....rk. If a unit fails, (A/C or component), it costs C per unit time, where n is the state of the system. The problem is to choose repair policy; as a function of the state of the system; which minimizes the long run expected total costs of the system repair. A model is constructed to deal the problem in two cases: — Case of poission arrivals and exponential repair time. Case of general arrivals and exponential repair time. An optimization procedure is deduced for both cases, then the problem is computerized through a FORTRAN IV program, the model is then applied through a case study on EGYPTAIR fleet and the optimum policy is deduced through the model's computer program.