gerwitz@Kodak.Com (Paul Gerwitz) (11/13/90)
Now that Columbia seems to be back together and ready to launch... I don't recall any mention of the actual causes of the hydrogen leaks that plagued it over the summer. Maybe I just wasn't paying real close attention this time around. Any quick explanations ?? -- +----------------------------------------------------------------------------+ | Paul F Gerwitz WA2WPI | SMTP: gerwitz@kodak.com | | Eastman Kodak Co | UUCP: ..uunet!atexnet!kodak!eastman!gerwitz | +----------------------------------------------------------------------------+
gsh7w@astsun.astro.Virginia.EDU (Greg Hennessy) (11/13/90)
In article <1475@eastman.UUCP> gerwitz@Kodak.com writes:
#Now that Columbia seems to be back together and ready to launch...
#
#I don't recall any mention of the actual causes of the hydrogen leaks that
#plagued it over the summer. Maybe I just wasn't paying real close
#attention this time around. Any quick explanations ??
The problem over the summer was in the 17 inch disconnect valve, which
had scratches in the telfon seals. The scratches were caused by small
glass beads. How the beads got there is unknown, but I have hard at
least two theories. When they were putting back together the engines
after fixing the disconnect valve, two seals were crushed, causing
leaks. In fixing one leak they introduced two more. The procedures
were changed to prevent a reoccurance of this event.
--
-Greg Hennessy, University of Virginia
USPS Mail: Astronomy Department, Charlottesville, VA 22903-2475 USA
Internet: gsh7w@virginia.edu
UUCP: ...!uunet!virginia!gsh7wgregc@cimage.com (Greg Cronau) (11/14/90)
In article <1475@eastman.UUCP> gerwitz@Kodak.com writes: >Now that Columbia seems to be back together and ready to launch... > >I don't recall any mention of the actual causes of the hydrogen leaks that >plagued it over the summer. Maybe I just wasn't paying real close >attention this time around. Any quick explanations ?? > The result has been the bane of diagnosticians for a long time: When they set up a system to allow them to watch it real carefully, It didn't leak! gregc@cimage.com
Wales.Larrison@ofa123.fidonet.org (Wales Larrison) (11/16/90)
>Now that Columbia seems to be back together and ready to launch... >I don't recall any mention of the actual causes of the hydrogen >leaks that plagued it over the summer. Maybe I just wasn't paying >real close attention this time around. Any quick explanations ?? The scuttlebutt in the industry was that the Columbia problems were caused by the new MLP used, and some mis-judgements and untrained technicans. Now this is "third bar seat on the left" unoffical rumor data, but I've heard it from a couple of sources. The Mobile Launch Platform (MLP) used for the initial tanking test was a new one - and the cleaning procedures used on the cryo lines through the MLP through the aft end of the orbiter and into ET weren't really up to snuff. When they did the first tanking test, they found cleaning material grit in the fuel system filters (used to clean the MLP cryo lines before use...) - and since that is very highly abrasive, and not something you want to run through high speed turbopumps, and shouldn't have been there in the first place - they decided to dissamble and clean out the MPS (Main Propulsion System) feedlines in the aft end of the orbiter. The MPS system is pretty complex, since the systems are very complex physically, pretty sizable (each line is about 24" across), and are vacuum jacketed and foamed. There are about 83 pieces which have to be fitted back together and tested. Disassembly and reassembly has been done several times - each system is assembled and tested at the Rockwell manufacturing plant in Palmdale, California when each shuttle is built, and at the Arrowhead Products plant in Southern California, when they make the parts before shipping them to Rockwell Palmdale. Nobody knew of one being stripped and reassembled at KSC. The rumor goes that Rockwell Palmdale and Arrowhead Products quickly put together a team to go down to KSC and perform the work needed - figuring the most experienced team would do the job the quickest and best. However, NASA KSC and Lockheed, the Shuttle operations contractor to NASA KSC, have been pushing for more maintenance work to be done at KSC. (They figure after the Endeavour is built, all of the Rockwell technicans will be out of a job, so they'll have to fix it themselves...) So they decided that Lockheed shuttle techs would strip down, clean, and reassemble the MPS at KSC. However, in putting the system back together, several teflon seals were "crushed", which allowed the leaks. This required dissasembling and retesting the system, yet again. To their credit, the Lockheed techs did manage to get it put back together the right way, and the tested leak rate is the lowest of any shuttle. Remember - this is rumor - and unconfirmed by any published reports. -- Wales Larrison Internet: Wales.Larrison@ofa123.fidonet.org Compuserve: >internet:Wales.Larrison@ofa123.fidonet.org --------------------------------------------------------------------------