scope:

Description of Driving Event:

The Orbiter Processing Facility (OPF) Bay 2 Firex Deluge Zone 3 Viking arm valve AV1.3-2 was leaking, and on September 21, 1989, Problem Report (PR) number PV-6-140247 was initiated to replace defective parts. During system leak check operations following valve repair, water flow from zone 3 (directly over the Orbiter) occurred in OPF Bay 2. The time of first flow was established as 10:28 AM on September 24, 1989, as recorded by OPF Water Pump House instrumentation due to diesel pump startup. The Zone 3 water flow over the Orbiter was at a reduced rate, with only a partial nozzle discharge pattern.

Shuttle Processing Contract (SPC) Water Systems technicians were cycling the manual arming and firing valves while leak checking the system. Only a few minutes had passed from the time they cracked open (2 turns) the system manual supply valve until they heard about the water flow problem in Bay 2. The SPC Lead Water Systems technician ran into the OPF to see what was wrong and noted the deluge flow. He returned to the manual activation station behind the OPF and found that two SPC ground support equipment (GSE) technicians had opened the manual arming and firing valve to Zones 1, 2, 3, 4, and 5. (It is presumed Zone 3 did not flow additional water and had been deactivated by this time.) The Lead Water Systems technician then closed all the open manual arming and firing valves, as well as the manual supply isolation valves to stop all Bay 2 water flow.

The scenario that lead to the two GSE technicians being at the deluge system manual flow control valve station is as follows:

After the flow from Zone 3 occurred, the SPC OPF Bay 1 Site Division Manager asked a GSE technician to find someone who could turn the system off. This GSE technician, accompanied by a co-worker, proceeded to the manual activation station behind Bay 2. Upon arrival, they proceeded to position the manual arming and firing valves to Zones 1, 2, 3, 4, and 5 to the "on" position, thinking they were turning the firex system off. This turned on deluge system Zones 1, 2, 4, and 5 (Zone 3 had already been deactivated) to the "full on" mode. The Lead Water Systems technician then returned to the manual valve panels, proceeded to turn the manual arming and firing valves to the "off" position, and then helped his technicians close the manual supply isolation valves to Zones 1 through 5, which stopped all water flow.