Welcome to Flightinfo.com

  • Register now and join the discussion
  • Friendliest aviation Ccmmunity on the web
  • Modern site for PC's, Phones, Tablets - no 3rd party apps required
  • Ask questions, help others, promote aviation
  • Share the passion for aviation
  • Invite everyone to Flightinfo.com and let's have fun

Launch Scrubbed for today

Welcome to Flightinfo.com

  • Register now and join the discussion
  • Modern secure site, no 3rd party apps required
  • Invite your friends
  • Share the passion of aviation
  • Friendliest aviation community on the web

rvsm410

Well-known member
Joined
Oct 27, 2003
Posts
690
discovery will not happen today...low fuel pressure sensor failure in the ET...They will de-tank and examine the sensors and or replace....dont know how long this will take...tomorrows window will be at 15:28 Friday will be at 15:08...


Safe than sorry....good call...
 
How do they find this stuff? Do they have sensors sensing the sensors?? Most of the no-go items that I find are usually very obvious by the time I find them (puddles of oil/fuel/hydraulic fluid). I would have no clue that the low fuel pressure sensor is broken unless it was on/abnormal all the time. I am thinking that there must be a self test/full cycle feature built into the sensor.
 
Test circuit

RockyMnt1 said:
How do they find this stuff? Do they have sensors sensing the sensors?? Most of the no-go items that I find are usually very obvious by the time I find them (puddles of oil/fuel/hydraulic fluid). I would have no clue that the low fuel pressure sensor is broken unless it was on/abnormal all the time. I am thinking that there must be a self test/full cycle feature built into the sensor.


One of the speculations on the NASA channel was that it was a problem with the test circuit for the sensor; which supports the conclusion that there is a self test feature built into it.
 
RockyMnt1 said:
How do they find this stuff? Do they have sensors sensing the sensors?? Most of the no-go items that I find are usually very obvious by the time I find them (puddles of oil/fuel/hydraulic fluid). I would have no clue that the low fuel pressure sensor is broken unless it was on/abnormal all the time. I am thinking that there must be a self test/full cycle feature built into the sensor.

My understanding is that two of four low-fuel-level sensors were indicating low hydrogen levels in the recently topped-off tank, which of course doesn't make sense. According to CBS news:

"The sensors let the computers know when the tank is dry and they can shut the engine down. If the engines were to continue running at high speed without fuel, it could lead to a catastrophe. It was not the first time these sensors malfunctioned. During a fueling test of Discovery's original tank in April, some of the sensors gave intermittent readings. NASA could not ascertain the exact reason for the failure but replaced the tank for other reasons."

Sounds like they were aware of a potential problem in April but didn't address it. According to ABC news:

"Shuttle managers considered conducting a fueling test at the launch pad on the replacement tank, but ruled it out to save time, saying that the actual fueling on launch day would be the ultimate test."

Sure was.

Gotta hand it to those guys and gals, though.... they're literally monitoring 20,000 (twenty thousand) parameters prior to a launch.

Full articles:
http://abcnews.go.com/Technology/wireStory?id=935773
http://www.cbsnews.com/stories/2005/07/13/tech/main708664.shtml
 
I sure hope that the guy making the fix is an A&P and that they get an IA sign off before flight!! GOtta keep the FAA happy. Of course, the log books must be updated too. I would sure like to see the airworthiness certificate for this thing.
 
If the engines were to continue running at high speed without fuel, it could lead to a catastrophe.


Typical media Nonsense. How can an engine- any engine- continue to run without fuel? Hello?

All four of the sensors are required for flight, and two of them were periodically giving false empty readings. They sense when the External Tank is empty, and tell the computer when to shut the engines down. If they were to give a false reading during the main engine burn, the shuttle might have too much energy to return to the Cape, and too little energy to reach the abort fields across the Atlantic. In that case, the crew would have to bail out and go for a swim, and we would lose the orbiter.
Probably a good idea to scrub the mission, but still, those sensors should have been changed at the first sign of trouble.
 
Please remember one thing....for all these years I have worked on the orbiters, and since i left the program in 99', the media has got to find a way to hipe up the story line...many times they just get it wrong, mis-quote, or make assumptions....

As to the sensors....I can only tell you in general, that every single inch of wiring, sensors, avionics, and all the systems have redundant backups that run ongoing diagnostics all the time by the GPC's (general Purpose Computers) I believe there are 4 of these on board.....I am sure they would know who, when, where and how long one of the astronauts pass wind!

Bottom line, NOTHING is over looked, and on this mission, they are being extra careful that everything is in the green.....no exceptions...

Obviously 7 lives are at stake, but the whole program will be at risk everytime we/ they launch a Space Shuttle for the duration of this program....tens of thousands of jobs, billions to the economy, FL, TX, and many other states....
The early retirement of the program now scheduled for 2010, has everyone worried about our future employment....the follow on vehicle is still in the design phase, years away from reality.....there will be alot of down time, lost talent before another vehicle will be able to replace this one...

For all her fragility and downfalls, this has been one wonderful machine, a true marvel of mankind....its not Star-Trek, but it is the first steps to get there, the media and the American Public forget this all the time...Space is always going to be an all or nothing proposition......there is no room for errors there......
 
EagleRJ said:
Typical media Nonsense. How can an engine- any engine- continue to run without fuel? Hello?

Maybe they're concerned about spewing LOX all over the place without any hydrogen to mix with it......

This non-NASA-insider speculative crap is freaking awesome! People who actually know what they're talking about...... just go play with your slide rules or something whilst the rest of us project our Cessna and Piper paradigms onto the U.S. space program.
 
RockyMnt1 said:
I sure hope that the guy making the fix is an A&P and that they get an IA sign off before flight!! GOtta keep the FAA happy. Of course, the log books must be updated too. I would sure like to see the airworthiness certificate for this thing.



I wonder if the shuttle pilot has his glider licence...................
 

Latest resources

Back
Top