That caused a short circuit in two separate main engine controllers during launch of mission STS-93.

In the orbiter Columbia's payload bay, the head of a screw (shown here) is identified as the probable cause of damage to a wire that caused a short circuit in two separate main engine controllers during launch of mission STS-93. As a result of the findings of electrical wiring inspections, Shuttle program managers have decided to inspect the wiring in Endeavour's payload bay before its next mission, STS-99. The inspection and possible repair work will lead to a delayed launch date no earlier than Oct.7. The primary payload of the mission is the Shuttle Radar Topography Mission, a specially modified radar system that will gather data for the most accurate and complete topographic map of the Earth's surface that has ever been assembled