Page 74

National Aeronautics and Space Administration

EVA23Water Intrusion

sounded normal. TP B was closed, and no water leaks were observed. Cooling water flow was detected by noting a coolant temperature drop at the sublimator water flow outlet, displayed on the DCM. The helmet was installed and an internal suit pressure of about 0.8 psid was noted. A globule of water was observed near TP B, but the consensus was that this was left over from the “golf ball� effluent previously noted. The water was absorbed onto wipes, and no recurrence was noted over the remainder of the operation. The system was allowed to run for a total of about an hour and ten minutes with no leakage evident at any location. After the helmet was removed, another inspection was performed of the suit interior and, again, no evidence of leakage was found. The conclusion drawn was that the leakage problem encountered during EVA 23 was caused by a failure condition residing somewhere in the FPS water separator components. Figure 3-34 presents a comparison of fan speed before any of the replacement activities, and after the I-134, I-141 and I-123 replacements. This figure graphically illustrates the effect of water carryover on fan speed. The constant fan speed observed after the I-123 R&R is in stark contrast to the decrease in speed experienced while the failure condition was still present.

Figure 3-34. Comparison of Fan Motor Speed and UIA Current Before and After I-134, I141, and I-123 Replacement

67

ISS EVA Suit Water Intrusion Mishap Investigation Report  

Report of the NASA Mishap Investigation Board examining the high visibility close call event of July 16, 2013 when ESA astronaut Luca Parmit...

Advertisement