scope:

Description of Driving Event:

On July 26, 1990, 14:06 EDT, a Payload Hazardous Servicing Facility (PHSF) fire alarm indication was received at the Protective Services Control Center (PSCC) in the Launch Control Center (LCC). Fire services responded and found no alarm indications at the facility. Initial troubleshooting by EG&G Fire Alarm (F/A) technicians indicated the trouble was on the communications pair between the PHSF and the PSCC.

At 17:48 EDT, a communications technician was dispatched to the PHSF, to support troubleshooting of the problem. The technician arrived at the PHSF Control Building and checked the signal pair at Frame 102. Indications were that the problem was at the Service Building end of the line. He then proceeded to the Service Building and, upon entering, heard an audible alarm. Reporting the alarm, via radio, to the trouble desk at the Communications Distribution & Switching Center (CD&SC), he proceeded to the other side of the facility to find someone to ask about the alarm.

Meanwhile, the security guard having reported the audible alarm to the PSCC, via radio, performed a perimeter sweep of the building and encountered the LSOC technician. After some discussion the technician resumed his troubleshooting and the guard continued the sweep.

Fire Services responded to the facility and found a Fire Alarm Indication for Zone 19, indicating the Water Deluge System had been activated. Checking showed that the ARM valves had been activated, which caused the Fire Alarm indication. However the ACTIVATE valves were still closed and no water was flowing.

The Gamma Ray Observatory spacecraft was located in Zone 1 of the Service Building highbay. The Water Deluge System for Zone 2 had been armed. Water flow from Zone 2 would not have caused direct impingment on the spacecraft but could have caused extensive water damage requiring retesting and repair.

Analysis of the system uncovered several design and implementation deficiencies that could have contributed to the close call, but no positive evidence was found to explain the anomaly.

Possible causes:

1. Manual activation of pushbutton by an unknown party.

2. Inadvertent short of terminals by the LSOC technician.

3. Intermittent short in cable plant.

A rash of recent false alarms at the PHSF uncovered a problem with the underground cable plant. Due to a malfunction with the air dryer, water was being pumped into the cables along with the air purge, which caused numerous shorts. A similar set of circumstances could explain the July 26, close call. Several recommendations have been made in this report to correct these deficiencies and ameliorate the possible causes. Other facilities with similar system configurations should also be reviewed.