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Description of Driving Event:

The practice of cannibalization has almost become a standard procedure during orbiter processing due to insufficient spare parts. This causes a significant increase in the overall processing effort. The removal of a needed LRU from the orbiter being cannibalized is an unplanned activity. A second activity, installing the removed LRU in the receiving orbiter, has usually been allowed for in the overall contingency planning; but the process flow time is impacted because it takes longer to cannibalize a part than to retrieve one from storage. When a LRU is obtained and reinstalled in the cannibalized orbiter, it must be retested. The replacement of the removed LRU and its retest are added work. Also, the increase in activity required for the unscheduled removal/replacement always increases the potential for damage. The follow-on tests that are performed to verify that no damage occurred are another unplanned addition to the workload. Three hundred parts were required during the launch processing of challenger for the STS 51-L mission. Of these, 45 were cannibalized from OV-103. In future decisions on whether to use a spare LRU or cannibalize, the use of a spare, when available, should be considered the first choice. Overall, cannibalization is an inefficient way to process an orbiter.