yee@trident.arc.nasa.gov (Peter E. Yee) (06/03/90)
Kennedy Space Center Shuttle Status
Thursday, May 31, 1990 11:00 a.m.
STS-35 -- COLUMBIA (OV-102) - LAUNCH PAD 39-A
Technicians continue inspections of the shuttle Columbia's
17 inch disconnect area to isolate the leak in the liquid
hydrogen line that caused managers to scrub Wednesday morning's
launch attempt of Space Shuttle Mission STS-35.
At 5:00 p.m. yesterday, the remaining liquid hydrogen boiled
off from the external tank and was replaced with an inert gaseous
helium purge. At 3:15 a.m. this morning, workers gained access
into the orbiter's aft compartment for a visual inspection. At
4:00 a.m., the first low pressure leak checks were performed with
the 17 inch disconnect valve remaining in the open configuration.
The external tank was pressurized up to 10 psi, however, no leaks
were detected in the disconnect seals. Leak checks were also
taken near the vent ports, on the post actuator drive, and the
shaft seals, in the locked and unlocked position. No leaks were
detected.
A visual inspection was made of the 17 inch foam insulation
on the feed lines. No problems were identified.
The detailed examination has resulted in discovery of a leak
in a 1/4 of an inch diameter flex line connector which is a part
of the LH2 manifold.
Continued troubleshooting will include leak checks to
determine if the leak rate can explain the quantities of hydrogen
detected in the aft compartment during propellant loading Tuesday
evening.
Later this morning, the 17 inch disconnect valve will be
closed and engineers will visually look for any obvious abrasions
in the welds on the joints. Then the external tank will be
pressurized to 25 psi and a small volume helium decay check will
be performed in an effort to duplicate the leak and pin-point its
location.
At 2:00 p.m. today, following the conclusion of the low
pressure leak checks, the orbiter's on-board PRSD tanks will be
drained of their cyrogenic propellants. This operation will take
six to eight hours to complete. Following this, the payload bay
doors will be opened allowing workers to gain access to the
ASTRO-1 payload for servicing.
Mission managers will be meeting throughout the day today to
discuss options for scrub turn-around.fmgst@unix.cis.pitt.edu (Filip M Gieszczykiewicz) (06/04/90)
> Kennedy Space Center Shuttle Status > Thursday, May 31, 1990 11:00 a.m. > > STS-35 -- COLUMBIA (OV-102) - LAUNCH PAD 39-A > > > A visual inspection was made of the 17 inch foam insulation ^^^^^^^^^^^^^^^^^ > on the feed lines. No problems were identified. > > Later this morning, the 17 inch disconnect valve will be > closed and engineers will visually look for any obvious abrasions ^^^^^^^^^^^^^ > in the welds on the joints. Then the external tank will be Greetings. About the underlined text: Interesting, anyone know why they don't use better and more precise methods like ultrasound or Xrays to find faults in welds. If industry uses such technology then why doesn't the STS team? Or am I missing the point - "visual inspection" IS those methods? It just seems to me that, from my _limited_ expirience, welds tend to crack and waken on the INSIDE; not where a visual inspection will catch them... Anyone? Take care. -- _______________________________________________________________________________ "The Force will be with you, always." It _is_ with me and has been for 10 years Filip Gieszczykiewicz "..of future fame...." "Ok! So I have a dream..." FMGST@PITTVMS or fmgst@unix.cis.pitt.edu "My ideas. ALL MINE!!"
petej@phred.UUCP (Pete Jarvis) (06/05/90)
In article <24675@unix.cis.pitt.edu> fmgst@unix.cis.pitt.edu (Filip Gieszczykiewicz) writes: > > Interesting, anyone know why they don't use better and more >precise methods like ultrasound or Xrays to find faults in welds. >If industry uses such technology then why doesn't the STS team? >Or am I missing the point - "visual inspection" IS those methods? > It just seems to me that, from my _limited_ expirience, welds >tend to crack and waken on the INSIDE; not where a visual inspection >will catch them... Not necessarily. First you do a visual inspection to see if there is anything obviously wrong. Pretty difficult to do X-ray on an installed component. Their helium signature leak test is supposed to catch out-of- limits leakage. Helium is a "small" molecule and will penetrate a leak for detection by sensors and spectrum analyzers. There is probably a nominal leakage signature(s) for various parts of the engine compartment and ET. .........Peter Jarvis.........Physio-Control Test Engineering