WASHINGTON Leaking coolant lines in a test rocket engine were caused by the stresses of repeated testing and not by a major design problem, the agency reported Friday.
As a result, test firings of the advanced LE-7A engine will commence again next week, according to the National Space Development Agency (NASDA) of Japan.
Holes were found in part of the nozzle of the no. 1 qualification engine following earlier testing. As a result, leaking coolant caused higher than planned temperatures in the engine during its last static firing at the Tanegashima Space facility.
To solve the problem, NASDA said it would install a skirt in the engine to avoid the effects of the repeated firings. Since the engine is to be used only once during a launch, no effect is expected on the actual LE-7A development program.
The resumption of test firings will start Aug. 9 with a short duration test of the no. 2 qualification engine without the skirt installed. A longer test Aug. 12 will be conducted with the new skirt, followed by tests Aug. 21 and 30 of long duration burns with the installed skirts.
The LE-7A will be used to power the next generation of H-II heavy lift space boosters, the H-IIA scheduled to begin flight trials next year with Japanese satellite payloads aboard.
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