scope:

Description of Driving Event:

During removal of the purge adapter from thruster R4D, liquid MMH was observed leaking from the thruster nozzle. When the leak was discovered the OPF high bay hypergolic exhaust fans were actuated, the high bay evacuated, and fire and medical support were requested to stand by. The leaking MMH was caused by a liquid trap present in the fuel suction hose. The trap was formed by excessive hose length, which was routed to the next level above, then down to the purge adapter. The routing and hose length was left over from a previous operation on the left side of the orbiter.