Engine validation tests are important stages of the production development process. Time and cost of these tests have important role in this process. Validation tests investigate performance (function) and durability of engine systems and parts. In recent markets developing of vehicles has accelerated and the validation process should be decreased. Farther more some concepts such as reliability has been serious in this field. Durability tests are longer stages of the validation process and some of them last some weeks. The subject of the accelerated life tests (ALT) is the acceleration of the durability tests without reliability variation. Two manners developed for accelerating durability tests (and decreasing test duration): increasing the severity of loading or removing the cycles that have no (low) influence on failures. In the present research the accessory belt tensioner bracket (feadbracket) tested with the engine supplier procedure for 436 hrs without any failure. In order to accelerating durability test, the belt load increased 1.4 times and bracket was fractured after 200 hrs. After that failure time of the bracket in the usual test extracted via finite element method (FEM) and fatigue models, then the accelerated test time calculated by reliability equations. Results show that ALT duration become less than 200 hrs.