scope:

Description of Driving Event:

During LOX transfer operations in preparation for a Space Shuttle Main Engine (SSME) test (904- 362) on the B-1 test stand, a LOX pump (barge #1, pump B) over pressurized, initiating a fire on barge #1. The fire was extinguished and mishap investigation procedures were initiated. The primary cause (determined by the board) was the backing out of a retaining screw during LOX pump B operations. Further investigation highlighted the following:

1. SSC's procurement (post 1988) of pump casings with configurations that were not per design (beveled area around retaining screw area), and

2. Wear rings for the pump are re-used after pump rebuild if no evidence impeller to wear ring wear exists.

The incident caused no injuries; however, damage to equipment including the barge, motors, lines, and decking is estimated at approximately $250,000. In addition, the pending SSME test was cancelled and rescheduled.