OT: What can be so problematic about fuel sensors?

[Fred Bloggs]

...They argued that if the O-rings were colder than 53 °F
(approximately 11.7 °C), there was no guarantee the O-rings would seal
properly. ...

I don't believe any of that, except the typically wishy-washy
phraseology. Instead of 'no guarantee' they should have emphasized that
the risk of catastrophic failure would be *well* above the acceptable
threshold for mission safety. Also the commission criteria for
concluding NASA management 'knew' anything about it was predicated on
the accessible documentation and verbal communication. What they really
mean is 'knew or should have known'.

 

[Paul Hovnanian P.E.]

Do you actually think that NASA doesn't 100% duplicate the environment
found inside those tanks (devoid of moisture) when they run tests on
removed gear?

Why would they do that? This failure didn't result in the loss of life
or the craft. It simply postponed the mission for a few weeks. The
failure was detected and dealt with.

A test/redesign program to correct such a problem might not be worth the
cost at this point in the shuttle's life.

 

[Jim Thompson]

Why would they do that? This failure didn't result in the loss of life
or the craft. It simply postponed the mission for a few weeks. The
failure was detected and dealt with.

A test/redesign program to correct such a problem might not be worth the
cost at this point in the shuttle's life.

If all sensors fail, the tank runs bone dry, then KA-BOOM! Thus the
concern.

...Jim Thompson

 

[Paul Hovnanian P.E.]

If all sensors fail, the tank runs bone dry, then KA-BOOM! Thus the
concern.

If the sensors are known to fail to a 'tank empty' state, who cares? You
might get an early engine shutdown and fail to reach orbit. But they are
supposed to have procedures for this.

 

[Jim Thompson]

[snip]

If all sensors fail, the tank runs bone dry, then KA-BOOM! Thus the
concern.

If the sensors are known to fail to a 'tank empty' state, who cares? You
might get an early engine shutdown and fail to reach orbit. But they are
supposed to have procedures for this.

You missed the point. They want engine shut-down BEFORE a COMPLETELY
empty tank, to avoid explosive conditions. The sensors were failing,
showing LIQUID H2 present, when none was there.

...Jim Thompson

 

[Paul Hovnanian P.E.]

[snip]

If all sensors fail, the tank runs bone dry, then KA-BOOM! Thus the
concern.

If the sensors are known to fail to a 'tank empty' state, who cares? You
might get an early engine shutdown and fail to reach orbit. But they are
supposed to have procedures for this.

You missed the point. They want engine shut-down BEFORE a COMPLETELY
empty tank, to avoid explosive conditions. The sensors were failing,
showing LIQUID H2 present, when none was there.

Ok. I re-read the article. You are correct. The sensors failed in the
'full' position.

However, it doesn't change the reasoning for why this stuff doesn't get
fixed. It appears that this fault was revealed in a 'de-tanking'
operation. In fact, this operation seems to be designed to expose such
faults. It appears that the economics of this situation is such that its
cheaper to do the test rather than re-engineer the system.

 

[ChairmanOfTheBored]

ChairmanOfTheBored [email protected] posted to
sci.electronics.design:


There can be a big difference between tests with no moisture and the
real tanks where it may be available. Test design matters.

Atmospheric air is never introduced into those tanks, so tell me where
the moisture gets into them from.

 

[ChairmanOfTheBored]

ChairmanOfTheBored [email protected] posted to
sci.electronics.design:


NO, i don't. Not you, always wrong.

**** you, idiot. Use your fucking brain. They are not using open
dewars, dipshit.