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Conference 7.286::space

Title:	Space Exploration
Notice:	Shuttle launch schedules, see Note 6
Moderator:	PRAGMA::GRIFFIN

Created:	Mon Feb 17 1986
Last Modified:	Thu Jun 05 1997
Last Successful Update:	Fri Jun 06 1997
Number of topics:	974
Total number of notes:	18843

822.0. "Any SRB Joint Performance Data?" by LANDO::STONE () Thu Sep 24 1992 08:54

    The recent problems being worked with Discovery's RH SRB gasket (See
    784.55) and the completion of the 25th mission since 51L (Challenger)
    prompts me to ask this question:
    
    As part of the data examined by the Rogers Commission, there existed
    detailed information about the incidence of "blow by" the primary
    SRB O ring for all the shuttle flights up to that point.  You may
    recall that blow by was where exhaust gases "leaked" by the primary
    ring and were stopped by the secondary ring (until 51L).  
    
    Does anyone have any corresponding data for the flights from STS 26
    until now?  No doubt that this information is being captured in order
    to measure the improved joint performance and stacking procedures.
    
    Thanks

T.R Title User Personal
Name Date Lines

822.1 UPI: Shuttle booster problem isolated (somewhat related to this topic) PRAGMA::GRIFFIN Dave Griffin Tue Sep 29 1992 20:47 50

T.R	Title	User	Personal Name	Date	Lines
822.1	UPI: Shuttle booster problem isolated (somewhat related to this topic)	PRAGMA::GRIFFIN	Dave Griffin	`Tue Sep 29 1992 20:47`	50
	From: [email protected] (WILLIAM HARWOOD, UPI Science Writer) Date: Wed, 23 Sep 92 17:04:33 PDT CAPE CANAVERAL, Fla. (UPI) - Engineers on Wednesday traced the cause of a tiny O-ring leak in a shuttle booster to a short section of U- shaped rubber stripping that inadvertently was ``pinched'' between two sections of the solid-fuel rocket. While there was no problem with the critical O-rings in the joint, NASA spokeswoman Lisa Malone said that engineers planned to replace the seals anyway and that no other problems were anticipated. The booster and another similar to it will be used to help launch the shuttle Discovery in November. The problem came to light Friday during routine tests to make sure the rocket was in good shape and ready for flight. Shuttle boosters are made up of four fuel segments that are bolted together at the Kennedy Space Center. Large rubber O-ring seals are used in each joint to maintain internal pressure and to help prevent a ``burn through'' such as the one that destroyed Challenger in 1986. In the wake of history's worst space disaster, NASA redesigned the O- ring joints to make them less susceptible to failure. Among the improvements were the addition of a third O-ring and a metal flange called a ``capture feature'' to firmly lock both sides of the joint together. In addition, testing procedures were intensified to catch any problems that might crop up. The seals in Challenger-era boosters were tested by pumping air into the joint between the primary and secondary O-rings at a pressure of 50 pounds per square inch. The seals now are tested at 1,000 psi, the booster's actual operating pressure. During a test Friday, sensors detected a slight leak between the primary and secondary O-rings in the central joint of Discovery's right- side booster. The leak was minuscule - it would not have been detected with the pre-Challenger leak test - but it violated NASA's tough post- accident safety guidelines. ``Basically, we're 13 times more stringent now than we were pre (Challenger),'' said Philip Weber, a NASA booster engineer. ``With the test that we did pre (Challenger) we wouldn't have seen this.'' Engineers suspected a defect with the leaky joint's primary O-ring, but that turned out not to be the case. When the booster segment was unbolted and removed Wednesday, engineers found that a section of rubber stripping used to prevent metal-on-metal contact in the joint had ``rolled over'' slightly during booster assembly, just enough to keep the primary O-ring from sealing properly. Malone said the booster would be reassembled using fresh materials and that no other problems were anticipated. Discovery had been scheduled to take off on a partially classified military mission around Nov. 5, but the flight already had been delayed to around Nov. 10 by an unrelated problem with a rear rocket pod. Work to fix the booster leak was not expected to cause any additional delay.

From: [email protected] (WILLIAM HARWOOD, UPI Science Writer)
Date: Wed, 23 Sep 92 17:04:33 PDT

	CAPE CANAVERAL, Fla. (UPI) - Engineers on Wednesday traced the cause
of a tiny O-ring leak in a shuttle booster to a short section of U-
shaped rubber stripping that inadvertently was ``pinched'' between two
sections of the solid-fuel rocket.
	While there was no problem with the critical O-rings in the joint,
NASA spokeswoman Lisa Malone said that engineers planned to replace the
seals anyway and that no other problems were anticipated. The booster
and another similar to it will be used to help launch the shuttle
Discovery in November.
	The problem came to light Friday during routine tests to make sure
the rocket was in good shape and ready for flight.
	Shuttle boosters are made up of four fuel segments that are bolted
together at the Kennedy Space Center. Large rubber O-ring seals are used
in each joint to maintain internal pressure and to help prevent a ``burn
through'' such as the one that destroyed Challenger in 1986.
	In the wake of history's worst space disaster, NASA redesigned the O-
ring joints to make them less susceptible to failure. Among the
improvements were the addition of a third O-ring and a metal flange
called a ``capture feature'' to firmly lock both sides of the joint
together.
	In addition, testing procedures were intensified to catch any
problems that might crop up.
	The seals in Challenger-era boosters were tested by pumping air into
the joint between the primary and secondary O-rings at a pressure of 50
pounds per square inch. The seals now are tested at 1,000 psi, the
booster's actual operating pressure.
	During a test Friday, sensors detected a slight leak between the
primary and secondary O-rings in the central joint of Discovery's right-
side booster. The leak was minuscule - it would not have been detected
with the pre-Challenger leak test - but it violated NASA's tough post-
accident safety guidelines.
	``Basically, we're 13 times more stringent now than we were pre
(Challenger),'' said Philip Weber, a NASA booster engineer. ``With the
test that we did pre (Challenger) we wouldn't have seen this.''
	Engineers suspected a defect with the leaky joint's primary O-ring,
but that turned out not to be the case.
	When the booster segment was unbolted and removed Wednesday,
engineers found that a section of rubber stripping used to prevent
metal-on-metal contact in the joint had ``rolled over'' slightly during
booster assembly, just enough to keep the primary O-ring from sealing
properly.
	Malone said the booster would be reassembled using fresh materials
and that no other problems were anticipated.
	Discovery had been scheduled to take off on a partially classified
military mission around Nov. 5, but the flight already had been delayed
to around Nov. 10 by an unrelated problem with a rear rocket pod. Work
to fix the booster leak was not expected to cause any additional delay.