scope:

Description of Driving Event:

A liquid helium dewar used to service payload experiments ruptured and damaged ceiling tiles and a copy machine. In order to service the payload experiments, the dewar converts normal liquid helium to superfluid helium. During this process, air was ingested into the vent line through a valve stem. The ingested air froze, forming a solid blockage. The failure analysis of the liquid helium dewar revealed that 4 of the 8 valves used in the system were not designed for use in vacuum systems.