scope:

Description of Driving Event:

Low flow rates were observed in the shuttle orbiter freon coolant loops when the temperatures in the radiator panels dropped below minus 60 degrees Farenheit during a mission. An investigation of the problem revealed that the system filters were clogged with teflon particles. The origin of the particles was traced to the krytox fluoropolymer thread lubricant grease used during loop assembly. Corrective actions were taken to remove, clean, and replace the system filters, several valves, a flow proportioning module, and a pump assembly.