Tokyo - April 25, 1998 - A report by an investigative committee of the National Space Development Agency of Japan has identified a welding failure between cooling tubes in the lower section of the LE-5A engine failure that stranded Japan's latet satellite in an elliptical orbit last month. The failure occured 44 seconds into an apogee raising maneuver which
should have lifted the 3.9 metric ton Communications and Broadcasting
Engineering Satellite to a geostationary orbit following an initially
succesful launch of the fifth H2 glight from Japan's Tanegashima Launch
Center on February 21.The report, released March 24 to the Science and Technology Agency in Tokyo, determined from telemtary data that while none of 240 nickel alloy cooling tubes in the second stage engine's combustion chamber failed, hot combustion gasses managed to penetrate special welding, called brazing between tubes in the lowest part of the combustion chamber nearest the top of the engine's nozzel skirt. Burning through the tubes, combustion gasses quickly caused a fire which triggered the engine shut down.
The report also detailed the engine's manufacturing process at Mitsubishi Heavy Industry's Nagoya Plant, central Japan and revealed that the engine had suffrered several failures realted to combustion chamber failure but determined these as unrelated to the launch accident as the engine had subsequently passed qualification and flight acceptance tests without further problems following repairs.
However rumors have surfaced that NASDA's testing might not have been all that it should have been. Watch this space.
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