National Aeronautics and Space Administration
ECFT-2.1 Large quantity of water from vent loop leaked into helmet during EVA 23. (Intermediate Cause 5) Supporting Evidence: The MIB determined through video transcripts of EVA and ground communication loops, and interviews that the water in EV2’s helmet was originating somewhere behind the crewmember’s head near the neck/lower head area. Post EVA, water was noted in and around the T2 vent port which is at the base of the crewmember’s head at the back of his neck (reference Figure 3-6). The MIB confirmed through video, that the quantity of water in the Astronaut’s helmet was estimated to be 1 to 1.5 liters. Given the limited volume of the helmet and the behavior of the water, this condition was life threatening. The MIB in conjunction with the ISS Investigation Team evaluated multiple sources of water in the suit. A significant effort was put into developing a detailed Fault Tree for the hardware failure (see Appendix G). This fault tree was developed and controlled by the ISS Investigation Team, but the MIB participated with the ISS Investigation Team and concurred with its accuracy and sufficiency. Investigations are continuing to resolve the cause(s) of the water in the vent loop. Additional root causes will be found. Proximate Cause ECFT-3 addresses the fact that no one called to terminate EVA 23 as soon as water was identified in the helmet which contributed to the severity of the event. The discussion below addresses the events and conditions relative to each team, starting with the EVA 23 Crew (Figure 3-46).
Flight Control Team/Crew did not terminate EVA as soon as w ater w as reported in the helmet. ECFT-3
EVA 23 Crew did not immediately recognize the severity of the event
Ground Team did not immediately recognize severity of the event.
Figure 3-46 Intermediate Causes Directly Under ECFT-3 ECFT-3.1 – EVA 23 Crew did not immediately recognize the severity of the event. (Intermediate Cause 6) Supporting Evidence: The MIB learned through discussions captured on audio loops between the ground control teams and the EVA crew members that neither of the EVA 23 crew initially recognized the severity of the water pooling at the back of EV2’s head. EV2 did not indicate a sense of urgency with
Published on Feb 27, 2014
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