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From: fosler@inmet.inmet.com
Newsgroups: sci.space.shuttle
Subject: Re: Shuttle scrubbed again (and a N
Message-ID: <18600001@inmet>
Date: 29 Sep 90 00:46:00 GMT
Lines: 21
Nf-ID: #R:<0093CF36.C756BB00@KING.ENG.UMD.:-36:inmet:18600001:000:1089
Nf-From: inmet.inmet.com!fosler    Sep 28 20:46:00 1990


     For thoose of you who do not get AW&ST, an article on the shuttle
delay says that NASA managers say the problem is not caused by
aging orbiter systems or by plumbing repeatedly subjected to flowing
hydrogen.  The orginal faults were traced to the umbilicals,
and the last set of leaks were confined to the orbiter aft engine
compartment and were not cause by the umbilicals.  The orginal
limits was 600 ppm, which was raised by Crippen to 1,000 ppm on
Sept 14.  During the fueling on Sept. 17, after switching from
slow flow to fast flow, hydrogen reached 2,200 ppm, flow was
reduced in hope that concentraction would revert to acceptable
limits, but when level peaked at 4,000ppm, the fueling was stopped.
    There is some belief amoung NASA's shuttle contractors that the
agency is being overly conservative in its assessment of the
hydrogen danger.
    It goes on to say that a manager of NASA says that NASA is comfortable
with levels of 10,000 ppm and that trobule-shooting would have been done
in that enviroment readily, but I do not understand what this means.


Carl Fosler