Headquarters, Washington, D.C. April 4, 1994
Johnson Space Center
LAUNCH ADVISORY -- STS-59 LAUNCH RESCHEDULED TO APRIL 8TH
Space Shuttle managers today decided to delay the launch of STS-59 to allow additional inspections of metallic vanes in the high pressure oxidizer preburner pump volute housings of Endeavour's main engines.
The inspections are expected to add at least one day to the launch preparations, and managers will review the findings once the inspections
are completed. A launch window for STS-59 on April 8th opens at
8:06 a.m. EDT.
The inspections are being performed after similiar main engine parts were found to be out of specification by about 30 thousandths of an inch regarding measurements of the radius of the metallic vanes. The vanes direct the flow of liquid oxygen as it is fed into the high pressure oxidizer turbopumps on the engines. The radius is a measure of the curvature of the metal, and a sharper curvature could reduce the tolerance of the metal to fatigue cracking.
The out-of-specification measurements were found on a housing undergoing proof testing at Rockwell's Rocketdyne Division, the main engine manufacturer. Some other preburner housings were then found to have similiar curvatures.
However, in more than 8,330 minutes of Space Shuttle Main Engine operations to date, no preburner housings have been found to have fatigue
cracks. In addition, cracks have never been found following proof testing of the housings, tests that subject the parts to much more severe pressures than experienced during flight. Due to the out-of-specification measurements, managers decided an inspection of the preburner housings installed in Endeavour's main engines to determine their radius would be prudent.
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