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NASA News
National Aeronautics and
Space Administration

John C. Stennis Space Center
Stennis Space Center, MS 39529-6000      BRH-03-044
(228) 688-3341         May 7, 2003

Lanee Cooksey        For Immediate Release
NASA News Chief
(228) 688-3341

SPACE SHUTTLE FLOW LINER SIMULATOR BEGINS TESTING TO EVALUATE
LONGEVITY OF SPACE SHUTTLE FLOW LINERS

HANCOCK COUNTY, Miss. - Stennis Space Center recently completed the
first in a series of tests on a Space Shuttle main engine flow liner
simulator dubbed the "battleship" on the A-1 test stand. Data
accumulated from the testing will help determine whether Space
Shuttle hydrogen lines can sustain 20 more years of flight operations
without being replaced.  NASA looked to Stennis in October to help in
resolving issues related to the small cracks found last June in the
orbiter's hydrogen fuel flow liners. Engineers believe the cracks to
be caused by high-cycle fatigue - a phenomenon in which the metal
rapidly flexes back and forth and then fails by cracking. The concern
is that a piece of the liner could break off and be carried into the
shuttle's turbopumps, possibly triggering an engine shutdown. Finding
out what causes the metal to flex back and forth is the next question
to be answered.  NASA's Keith Brock, deputy manager, Program
Integration Office at Stennis, said ground testing of the flow liners
during an engine test will provide data to help characterize the
environment the flow liners endure during flight.

"The simulator's design allows us to re-create the same flow
characteristics under the same conditions as in the orbiter, but it
gives us a heavier and safer platform on which to place
instrumentation," said Brock. "We will run a series of tests that
should give us information to confirm the cause of the cracks and
plan a permanent solution." 

Working with Mississippi Space Services designers Ken Broom, Dave
Alston and Allen Forsman, Stennis fabricated a flow liner simulator
that replicates a number of the conditions -- vibrations,
temperatures, pressures and fuel flow -- that might be factors in
high-cycle fatigue. 

The simulator is a highly specialized structure approximately 16
inches in diameter and constructed of stainless steel.

Stennis' tests collected data never gathered before. Engineers at
Johnson Space Center, Houston, and Marshall Space Flight Center,
Huntsville, Ala., will use this data to anchor analytical models to
confirm the cause of the cracks and make any recommendations for
future changes. 

The flaws may have been around since the Shuttle program began in
1981 but may have been too small to be detected. Welding was ordered
as a repair to the flow liner cracks.

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