National Aeronautics and Space Administration
4.0 Findings This MIB found the following issues that contributed to this incident. Root Causes, Proximate Causes, Intermediate Causes, Contributing Factors, and Observations are listed in this section. Since the investigation of the Fan/Pump/Separator is still ongoing, not all root causes have been identified.
4.1 Proximate Causes A Proximate Cause is the event(s) that occurred, including any condition(s) that existed immediately before the undesired outcome, which directly resulted in the occurrence of the undesired outcome and, if eliminated or modified, would have prevented the undesired outcome. Based on this definition, the MIB noted three (3) proximate causes for this HVCC. P-1.
The ISS Program conducted EVA 23 without recognizing the EMU failure which occurred on EVA 22
EMU 3011 Helmet had large quantity of water during EVA 23
Flight Control Team/Crew did not terminate EVA 23 as soon as water was reported in the helmet
4.2 Intermediate Causes An Intermediate Cause is an event or condition that created the proximate cause that, if eliminated or modified, would have prevented the proximate cause from occurring. Based on this definition, the MIB noted 19 intermediate causes. I-1.
Flight Control Team and Crew incorrectly attributed the water in the helmet during EVA 22 to the drink bag.
Flight Control Team did not perform investigation of the water source following EVA 22.
Flight Control Team accepted the explanation that the water during EVA 22 was from the drink bag.
Ground Team allowed time pressures of impending EVA to influence actions.
Large quantity of water from vent loop leaked into helmet during EVA 23.
EVA 23 Crew did not immediately recognize the severity of the event.
Crew member Training did not include this failure mode.
Flight Control Team focused on the drink bag as the source of the EVA 23 water.
Critical Information was not communicated between Crew and Ground Team.
Airflow Contamination procedure did not address the failure mode.
Flight Control Team did not understand the failure mode.
Team had Channelized Attention on the drink bag as the primary source of water in the helmet.
Team's set of responses led to a delay in identifying the vent loop as the source of the water leak.
Published on Feb 27, 2014
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