Transmission is a core component of helicopter to transmit power from engine to rotor and must have a endurance to be able to show satisfactorily its performance required during its life time. When developing a new helicopter, both military and civil airworthiness authorities require a tie-down test to verify its endurance. Procedure for transmission endurance test is described in FAR part 29 or US military specification but its details are more or less ambiguous. In this paper, we have proposed a proper procedure for transmission endurance test by giving KUH transmission endurance test example including determination of applicable torque, load and test profile.