Page 102

National Aeronautics and Space Administration

EVA23Water Intrusion

helmet, the air flow from the vent loop would force the water to streak over the top of the helmet and down the front of the visor, possibly affecting the crew member’s visibility. From evaluation of this event, the MIB and ground teams now know that the water entered the helmet, but did not streak over the top and down the visor. Instead, surface tension forced the water to form near the outlet of the vent line until the quantity was sufficient enough to contact the back of EV2’s head. At that point, surface tension brought the large amount of water to the back of EV2’s head and it eventually made its way to the front of EV2’s head, covering his eyes and nostrils. No further analysis was done on this ECFT leg—Root Cause was reached. ECFT- – FMEA/CIL did not undergo thorough review and update periodically. (Contributing Factor 9) Supporting Evidence: From a review of the EMU FMEA/CIL documentation and interviews, it was determined that the last re-baselining of the EMU FMEA/CIL was after the Challenger accident in 1986. As configuration changes are made to the hardware, appropriate changes to the FMEA are made and the CIL is reviewed and updated. During the CoFR process changes in dash numbers are noted and it is confirmed that no FMEA updates are required. The review and updates to the FMEA are not comprehensive and usually only the minimum necessary changes are made. The MIB noted several instances where the failure history associated with a FMEA was either incomplete or in error. See section ECFT- for more detail. The MIB determined that lack of FMEA/CIL review may not be determined causal but increased the likelihood that the FMEA/CIL did not reflect the failure mode seen in this HVCC. ECFT- – ISS program FMEA/CIL requirements did not require complete FMEA/CIL periodic review. (Contributing Factor 11) Supporting Evidence: From reviews of applicable ISS Safety and Mission Assurance documentation (SSP-30234, Failure Modes and Effects Analysis and Critical Items List Requirements for Space Station) and interviews with personnel, the MIB can find no requirement within the ISS Program to periodically perform a comprehensive review of FMEAs. See ECFT- for more detail. ECFT- – Program cut funding. (Contributing Factor 12) Supporting Evidence: From interviews and discussions with personnel, it was determined that an effort was underway to bring the EMU FMEA/CILs and hazard reports into compliance with the ISS Program requirements which should have resulted in a major review of the all of the documentation. This work was suspended due to budget cuts this year. ECFT- – Community had lost sight of the value of the FMEA/CIL effort. (Contributing Factor 13) Supporting Evidence: From SSP-30234 on the purpose of the FMEA post design phase: “The FMEA provides documentation of the failure modes present in the system, the effects of failure mode occurrence, the methods of detecting the failure, and corrective action taken to prevent effects of failure (including restoration of function). For critical failure modes, and when required to be submitted


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...