scope:

Description of Driving Event:

The throat plug and purge adapter assembly, located in the reaction control system (RCS) primary thruster, provides the means for sealing the RCS primary engine throat during activation, decontamination, and purging. The assembly consists of a tubular structure terminating in an expandable seal, which is inserted through the nozzle skirt. The plug is hand operable from the opposite end and expands the seal to a diameter larger than the nozzle throat, providing a positive mechanical interference to preclude blow-out. The plug end gasket is removable to permit inspection for cleanliness or deterioration. The assembly also includes a passage for ducting purge fluid during deactivating and purging to a toxic vapor disposal system. Improperly grounding or a lack of grounding may cause static electricity build-up and electrical sparks which could act as an ignition source for any flammable vapors present.